Changes in the occurrence of children’s asthma after the 2019 revision of the Health Promotion Act preventing passive smoking in Japan: interrupted time-series analyses

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In Japan, the Health Promotion Act was revised in February and July 2019, and regulations against passive smoking were strengthened to protect children. We evaluated the impact of the policy, which had remained unexamined. Methods We used the DeSC database in Japan. We included all children under the age of six years. Interrupted time-series analyses were conducted by fitting Prais–Winsten linear regression models to assess the association of the policy revisions with the outcomes, namely the monthly occurrence per 100,000 children of hospitalization or outpatient medication for severe asthma between May 2018 and March 2020. Results Neither the first revision in February 2019 nor the second in July 2019 was associated with a decrease in hospitalization for asthma or outpatient medication for severe asthma. The second policy was associated with a reduction in hospitalization for asthma among children whose parents had smoking habits. Conclusion Our findings show that the revised policies introduced in Japan did not decrease the occurrence of severe asthma in children. This can be attributed to a lack of awareness about the first policy among the public and only a marginal increase in compliance following the second revision among institutions serving vulnerable populations. This suggests that the Japanese government should implement measures to increase awareness of the policy and enforce strict repercussions for non-compliance. passive smoking asthma hospitalization smoking habits Japan Background Passive smoking contributes to serious health problems in children [ 1 ], including asthma and sudden infant death syndrome (SIDS). More than 70% of children up to 3-years-old and more than 80% of those up to six-years-old have asthma [ 2 ]. The incidence of SIDS is estimated to be 1 in every 6,000–7,000 births in Japan [ 3 ]. The incidence of asthma and SIDS is reported to be closely related to passive smoking [ 4 ]. Passive smoking is recognized as a major risk factor in parenting environments [ 5 ]. The incidence of SIDS is 1.5 times higher when the father smokes at home after the birth of his child [ 6 ]. Another study reported that the incidence of asthma in children aged 5 to 16 years was 23% higher in those exposed to passive smoking [ 7 ]. Several countries have introduced smoke-free policies to prevent passive smoking. A study in Scotland reported a reduction in the proportion of hospitalizations for childhood asthma following the introduction of the smoke-free policy in 2006 [ 8 ]. Another study in Arizona found that the statewide smoking ban was associated with a reduction in asthma-related hospitalizations, particularly in counties without previous ban regulations [ 9 ]. A meta-analysis showed that smoke-free laws were followed by fewer hospitalizations, and comprehensive regulations banning smoking in workplaces, restaurants, and bars were associated with a greater impact [ 10 ]. In Japan, the Health Promotion Act was revised on July 25, 2018, strengthening regulations against passive smoking to protect individuals, including children. To prevent passive smoking, the new regulation prohibits smoking in facilities used by the public and commercial means of passenger transportation, except in specified areas, and establishes measures to be taken by the managing authorities of these facilities [ 11 ]. The regulation served three purposes: to eliminate unwanted passive smoking, to protect children and vulnerable individuals from passive smoking, and to implement measures specific to the type and location of facilities. The regulation took effect in three phases. The first, which took effect on January 24, 2019, required the government to take action against passive smoking and mandated that all smokers consider their surroundings when smoking, even at home. The second step, which took effect on July 1, 2019, required smoke-free premises at facilities primarily used by vulnerable individuals, such as schools, hospitals, and child welfare facilities. The third measure, which took effect on April 1, 2020, established a general indoor smoking ban across all public facilities and transportation systems [ 12 ]. A survey conducted by the Ministry of Health, Labour and Welfare of Japan (MHLW) in 2022 on smoking environments revealed that compliance with the complete smoking ban in schools, child welfare facilities, medical institutions, and administrative agencies increased from 85.9% in 2019 to 87.4% in 2021 [ 13 ]. However, this survey did not assess the impact of this regulation on smoking practices at home. Another survey conducted in Osaka City in 2022 found that only 25% of parents who smoke at home refrained from smoking in front of their elementary school-aged children [ 14 ]. Despite the increased enforcement of smoking bans in facilities primarily used by individuals vulnerable to passive smoking, many children continued to be exposed to it at home. Thus, it remains unclear whether the regulation has had a positive impact on children’s health in Japan. Therefore, we conducted an interrupted time-series analysis to evaluate the impact of the policy aimed at protecting children from passive smoking on the occurrence of severe asthma and SIDS. Methods This study was approved by the Institutional Review Board of the University of Tokyo (No. 3501-(5); May 19, 2021). Since the data were anonymized, the requirement for written consent was waived. Clinical trial number: not applicable Data source We accessed the DeSC database (DeSC Healthcare Inc.), which comprises commercially available administrative claims and health checkup data, for the period between April 2014 and November 2022. This database includes information for approximately 12,500,000 individuals and health insurance claims data from three types of health insurers: (1) Health Insurance for employees of large companies, (2) National Health Insurance for the unemployed and individual proprietors, and (3) the Advanced Elderly Medical Service System for individuals aged 75 years or older. The claim data at the individual level is stored anonymously. The database includes data on infants, younger individuals, and older individuals, and contains the following information: family identifier; individual identifier; birth month; sex; duration of insurance; diagnosis encoded according to the International Classification of Diseases, 10th Revision (ICD-10); and drugs dispensed based on the Anatomical Therapeutic Chemical Classification System. In addition, the database contains information on the annual health checkup information for approximately 30% of the entire population. The annual health checkup data comprise health status, mental health status, dietary habits, oral function, weight change, physical function and falls, cognitive function, smoking, social engagement, and social support, assessed through a self-administered questionnaire [ 15 – 17 ]. The annual health checkup is voluntary and focuses on metabolic syndrome for individuals aged 40 to 74 years to prevent lifestyle-related diseases. The smoking section of the questionnaire includes the following question: “Are you currently a heavy smoker?” (“A heavy smoker” refers to those who have smoked over 100 cigarettes in their lifetime, and have smoked over a period of six months, including in the past month) [ 18 ]. Patients and outcomes We included all children aged younger than six years in our analyses. The measured outcomes were the monthly occurrences of SIDS and severe asthma per 100,000 children. SIDS was defined according to the ICD-10 codes presented in Supplementary Table 1. Severe asthma was defined as either hospitalization for asthma or medications prescribed during outpatient treatment [ 3 ], as listed in Supplementary Tables 1 and 2. For each month in the study period, we calculated the outcomes as the number of occurrences among all children registered in the claims data for that month. Variables The baseline characteristics of children who had died from SIDS or had severe asthma included age, sex, fiscal year, and the smoking habits of their parents. We determined the smoking status of their parents using health checkup data from April 2017 to March 2022. Statistical analysis First, we described the background characteristics of patients, stratified by the type of outcomes: SIDS, hospitalizations for asthma, and outpatient medication for severe asthma. Second, we created aggregated monthly data from May 2018 to March 2020 for the interrupted time-series analysis. Data were used to evaluate the impact of the policy that took effect on January 24, 2019, and July 1, 2019, assessed as “February 2019” and “July 2019,” respectively. A Prais–Winsten linear regression model was fitted to account for autocorrelation [ 19 ], and we analyzed the impact of the policy by estimating the following segmented regression model [ 20 ]: Y t = β 0 + β 1 T t + β 2 X 1t + β 3 T t X 1t + β 4 X 2t + β 5 T t X 2t where Y t is the monthly proportion of the outcome at time t ; T t is the number of months elapsed from the start of the observation period; X 1t is a dummy variable (taking values 0 and 1 for before and after the introduction of the first policy in February 2019, respectively); T t X 1t is the interaction term that indicates the months elapsed since the introduction of the first policy; X 2t is a dummy variable (taking values 0 and 1 for before and after the introduction of the second policy in July 2019, respectively); T t X 2t is the interaction term that indicates the months elapsed since the introduction of the second revision; β 0 indicates the baseline monthly proportion of the outcome; β 1 indicates the slope of the monthly proportion of the outcome before the first introduction; β 2 indicates the level change in the monthly proportion of the outcome immediately after the first introduction; β 3 indicates the slope change following the first introduction and represents the effect of the first intervention over time; β 4 indicates the level change in the monthly proportion of the outcome immediately after the second introduction; β 5 indicates the slope change following the second introduction and represents the effect of the second intervention over time; β 1 + β 3 indicates the slope after the first introduction; and β 1 + β 3 + β 5 indicates the slope after the second introduction. Additionally, the Durbin–Watson test was used to evaluate the autocorrelation between data points in the generalized least squares regression model [ 21 ]. Statistical significance was defined as p < .05. All analyses were performed using Stata/SE software (version 17.0; StataCorp, College Station, TX, USA). We did not analyze the impact of the policy that took effect on April 1, 2020 because we could not exclude the effects of the coronavirus pandemic in March. Subgroup analysis We identified all children aged younger than six years whose parents had smoking habits by linking the unique identifier assigned to all parents and their children under the same insurer. This was based on our assumption of a possible association between the occurrence of SIDS and asthma in children and smoking environments, supported by previous studies indicating that passive smoking is a major risk factor [ 5 – 7 ]. Subsequently, we conducted the analyses in the same manner as the main analyses. Sensitivity analysis We tested the robustness of our results using an alternative time bandwidth from June 2019 to February 2020. The Government of Japan decided on emergency response measures and established a fundamental policy for addressing the coronavirus in February 2020 [ 22 ]. In addition, we tested the robustness of our results by using either July 2018 or January 2019 as the sole intervention point, starting from April 2017. The Health Promotion Act was revised in July 2018, and it was assumed that government publicity campaigns were conducted and that preparations to prevent passive smoking in public institutions and public places were underway before full implementation in January 2019. Results Main analysis We identified 77,182 eligible patients, including 7 who died of SIDS, 6,638 who were hospitalized for asthma, and 70,537 who received medication for severe asthma in outpatient settings. The baseline characteristics of the children are presented in Table 1 . We excluded detailed information on SIDS to avoid raising concerns about the potential identifiability of individuals. Approximately 75% of those hospitalized for asthma were under 3-years-old, and there were more boys than girls. Approximately 78% of patients who received medication for severe asthma were aged three to six years, and there were more boys than girls. Table 1 Baseline characteristics of patients Period Overall May 2018–Jan 2019 Feb 2019–Jun 2019 Jul 2019–Mar 2020 Characteristics Hospitalization for asthma Medication for severe asthma at outpatient settings Hospitalization for asthma Medication for severe asthma at outpatient settings Hospitalization for asthma Medication for severe asthma at outpatient settings Hospitalization for asthma Medication for severe asthma at outpatient settings All, n (%) 6,638 (100.0) 70,537 (100.0) 2,766 (100.0) 29,000 (100.0) 1,353 (100.0) 14,888 (100.0) 2,519 (100.0) 26,649 (100.0) Age (years), n (%) 0 1,128 (17.0) 2,674 (3.8) 460 (16.6) 1,138 (3.9) 268 (19.8) 630 (4.2) 400 (15.6) 906 (3.4) 1 1,764 (26.6) 6,333 (9.0) 765 (27.7) 2,745 (9.5) 365 (27.0) 1,331 (8.9) 634 (25.2) 2,257 (8.5) 2 1,133 (17.1) 6,296 (8.9) 463 (16.7) 2,669 (9.2) 240 (17.7) 1,314 (8.8) 430 (17.1) 2,313 (8.7) 3 929 (14.0) 15,303 (21.7) 379 (13.7) 6,458 (22.3) 183 (13.5) 3,170 (21.3) 367 (14.6) 5,675 (21.3) 4 701 (10.6) 15,519 (22.0) 263 (9.5) 6,152 (21.2) 127 (9.4) 3,216 (21.6) 311 (12.4) 6,151 (23.1) 5 557 (8.4) 13,333 (18.9) 245 (8.9) 5,574 (19.2) 102 (7.5) 2,696 (18.1) 210 (8.3) 5,063 (19.0) 6 426 (6.4) 11,079 (15.7) 191 (6.9) 4,264 (14.7) 68 (5.0) 2,531 (17.0) 167 (6.6) 4,284 (16.1) Sex, n (%) Boy 3,969 (59.8) 39,675 (56.2) 1,646 (59.5) 16,372 (56.5) 822 (60.1) 8,325 (55.9) 1,501 (59.6) 14,978 (56.2) Smoking habits (parents), n (%) Yes 795 (12.0) 10,454 (14.8) 363 (13.1) 4,446 (15.3) 155 (11.5) 2,225 (14.9) 277 (11.0) 3,783 (14.2) The change in the yearly smoking proportion is presented in Supplementary Fig. 1. The smoking proportion decreased from 17.0% in 2017 to 14.0% in 2018 and remained unchanged thereafter. Table 2 shows the monthly number of patients stratified by outcomes: the number of patients aged younger than six years and the monthly occurrence per 100,000 children. The total number of deaths from SIDS was seven, which is too small a number for an interrupted time-series analysis. Table 2 The monthly number and occurrence of patients between May 2018 and March 2020 Time (month, year) Total population aged younger than six years, n Hospitalization for asthma Medication for severe asthma at outpatient settings n /100,000 n /100,000 May 2018 370,853 262 71 2,706 730 June 2018 369,665 295 80 2,722 740 July 2018 368,557 304 82 2,767 750 August 2018 367,144 334 91 2,566 700 September 2018 365,735 431 118 3,879 1060 October 2018 364,501 404 111 4,798 1320 November 2018 363,121 278 77 3,761 1040 December 2018 361,818 236 65 3,470 960 January 2019 360,486 222 62 2,331 650 February 2019 358,849 221 62 2,652 740 March 2019 357,369 262 73 3,324 930 April 2019 355,703 317 89 3,347 940 May 2019 354,120 287 81 2,798 790 June 2019 352,406 266 75 2,767 790 July 2019 350,544 290 83 2,807 800 August 2019 348,728 313 90 2,403 690 September 2019 346,696 418 121 3,660 1060 October 2019 344,628 379 110 3,991 1160 November 2019 342,720 267 78 3,567 1040 December 2019 340,915 261 77 3,151 920 January 2020 339,007 210 62 2,296 680 February 2020 337,369 244 72 2,707 800 March 2020 335,433 137 41 2,067 620 The results of the interrupted time-series analysis are presented in Tables 3 and 4 , and Supplementary Figs. 2 and 3. The monthly occurrence showed no significant trend throughout the study periods for both hospitalization and prescribed medication for severe asthma. The slope changes after the introduction of the first and second policies were also not significant for either hospitalization or prescribed medication for severe asthma. Additionally, the level changes at the first and second policy introductions were not significant for either hospitalization or prescribed medication for severe asthma. The results of the sensitivity analyses using an alternative time bandwidth between June 2019 and February 2020 were similar to those of the main analyses. (Supplementary Tables 3 and 4; Supplementary Figs. 4 and 5). The results of the sensitivity analyses using July 2018 as the intervention point showed no significant trends in either hospitalization or prescribed medication for severe asthma throughout the study periods. Supplementary Tables 5 and 6, and Supplementary Figs. 6 and 7. The sensitivity analyses using January 2019 as the intervention point also showed no significant trends except for the slope after the policy introduction. (Supplementary Tables 7 and 8, and Supplementary Figs. 8 and 9). Table 3 Monthly changes in the occurrence among patients aged younger than six years who were hospitalized for asthma between May 2018 and March 2020 The monthly occurrence among patients aged younger than six years who were hospitalized for asthma between May 2018 and March 2020 using the interrupted time-series analysis Coefficient 95% confidence interval P Slope before the first policy introduction -1.0 -6.6 4.6 .71 Level change after the first policy introduction -4.9 -31.0 21.0 .70 Slope change of the first policy 4.9 -6.3 1.6 .37 Slope after the first policy introduction 4.9 -4.0 1.2 .31 Level change after the second policy introduction 11.0 -28 5.1 .55 Slope change of the second policy -9.9 -21.0 1.3 .08 Slope after the second policy introduction -6.0 -13.0 0.5 .07 Table 4 Monthly changes in the occurrence among patients aged younger than six years who received medication for severe asthma at outpatient settings between May 2018 and March 2020 The monthly occurrence among patients aged younger than six years who received medication for severe asthma at outpatient settings between May 2018 and March 2020 using the interrupted time-series analysis Coefficient 95% confidence interval P Slope before the first policy introduction 15.0 -57.0 87.0 .67 Level change after the first policy introduction -33.0 -413.0 347.0 .86 Slope change of the first policy -23.0 -156.0 110.0 .72 Slope after the first policy introduction -8.2 -84.0 67.0 .82 Level change after the second policy introduction 82.0 -221.0 386.0 .57 Slope change of the second policy -16.0 -118.0 86.0 .74 Slope after the second policy introduction -24.0 -78.0 30.0 .35 Subgroup analysis We identified 11,249 eligible patients whose parents had smoking habits, including 795 who were hospitalized for asthma and 10,454 who received medication for severe asthma. The baseline characteristics of the patients are presented in Supplementary Table 9. Supplementary Table 10 shows the monthly number of patients aged younger than six years and the monthly occurrence per 100,000 children. The results of the interrupted time-series analysis regarding hospitalization for asthma are presented in Table 5 and Supplementary Fig. 10. The results were similar to those of the main analyses, except for the slope after the introduction of the second policy. Hospitalization for asthma showed a decreasing trend after the introduction of the second policy for the subgroup of children whose parents had smoking habits. The results of the interrupted time-series analysis regarding prescribed medication for severe asthma were similar to those of the main analyses presented in Table 6 and Supplementary Fig. 11. Table 5 Monthly changes in the occurrence among patients aged younger than six years who were hospitalized for asthma and whose parents had smoking habits between May 2018 and March 2020 The monthly occurrence among patients aged younger than six years who were hospitalized for asthma whose parents had smoking habits between May 2018 and March 2020 using the interrupted time-series analysis Coefficient 95% confidence interval P Slope before the first policy introduction -3.0 -13.0 7.0 .54 Level change after the first policy introduction -11.0 -83.0 61.0 .75 Slope change of the first policy 4.0 -17.0 26.0 .67 Slope after the first policy introduction 1.0 -14.0 17.0 .86 Level change after the second policy introduction 38.0 -37.0 114.0 .30 Slope change of the second policy -12.0 -31.0 6.0 .17 Slope after the second policy introduction -11.0 -21.0 -2.0 .02 Durbin–Watson statistic (original) = 1.41; Durbin–Watson statistic (transformed) = 1.73 Table 6 Monthly changes in the occurrence among patients aged younger than six years who received medication for severe asthma at outpatient settings and whose parents had smoking habits between May 2018 and March 2020 The monthly occurrence among patients aged younger than six years who received medication for severe asthma at outpatient settings and whose parents had smoking habits between May 2018 and March 2020 using the interrupted time-series analysis Coefficient 95% confidence interval P Slope before the first policy introduction 23.0 -138.0 183.0 .77 Level change after the first policy introduction 53.0 -801.0 906.0 .90 Slope change of the first policy -93.0 -375.0 188.0 .50 Slope after the first policy introduction -70.0 -220.0 80.0 .34 Level change after the second policy introduction 267.0 -287.0 820.0 .32 Slope change of the second policy 20.0 -173.0 214.0 .83 Slope after the second policy introduction -50.0 -136.0 35.0 .23 Durbin–Watson statistic (original) = 1.31; Durbin–Watson statistic (transformed) = 1.65 Discussion Using the DeSC database, we examined the impact of policies that prevent children from passive smoking on the occurrence of SIDS and severe asthma. The occurrence of SIDS was rare. An interrupted time-series analysis revealed that neither the first policy introduced in February 2019 nor the second introduced in July 2019 was associated with a decrease in hospitalization or outpatient medication for severe asthma. However, the second policy was associated with a decrease in hospitalizations for asthma among children whose parents had smoking habits. In addition, the interrupted time-series analysis revealed that the policy introduced in July 2018 was not associated with a decrease in hospitalizations or outpatient medications for severe asthma. According to surveys by the MHLW, the proportions of individuals with daily smoking habits were 16.4% in 2018 and 15.8% in 2019 [ 13 , 23 ]. The smoking proportions in this study were similar. The February 2019 policy required the government to take action against unwanted passive smoking and for individuals to consider their surroundings when smoking. The first policy was not associated with a decrease in hospitalization or outpatient medication for severe asthma. This lack of impact may be due to smokers being unaware of the regulation at the time of its introduction. According to a survey by the National Cancer Center Japan in 2023, 65.2% of all respondents over 20 years of age were unaware that the Health Promotion Act had been revised and that the policy against passive smoking had been strengthened, despite the fact that three years had passed since the revision [ 24 ]. In addition, the first policy may not have had an impact because it lacked penalties or enforcement. The second policy introduced in July 2019 required facilities primarily used by individuals vulnerable to passive smoking, such as schools, hospitals, and child welfare facilities, to be smoke-free. The second policy was also not associated with a decrease in the occurrence of hospitalizations or outpatient medication for severe asthma. This lack of impact may be because most of the facilities subject to the regulation had already banned smoking by the time the second policy was introduced. As previously noted, the MHLW survey found only a marginal increase in compliance with the complete smoking ban among schools, child welfare facilities, medical institutions, and administrative agencies [ 25 ]. The second policy was associated with reduced hospitalizations for asthma among children whose parents had smoking habits. According to a survey by the National Cancer Center Japan in 2023, 60.7% of individuals older than 20 years who smoke were aware that the Health Promotion Act had been revised and that the policy on passive smoking had been strengthened [ 24 ]. In addition to the findings from the survey, the proportion of smoke-free facilities remained unchanged at 84.9% in 2020 and 86.9% in 2021 [ 25 ]. There are few opportunities for passive smoking outdoors, including in streets and parks in Japan, as some local governments have enacted bans on public smoking. In fact, according to a survey by the MHLW in 2019, 2% of all respondents over 20-years-old were exposed to passive smoking daily on the streets, and 0.3% were exposed in outdoor areas frequently used by children, including schools and parks [ 23 ]. Therefore, considering the limited opportunities for passive smoking outdoors in the three years following the introduction of the second policy, parents who smoke and have children with asthma may have become more aware of passive smoking outdoors since that policy was implemented. In addition, the smoking proportion presented in Supplementary Fig. 1 remained unchanged after 2018 and slightly increased from 2019 to 2020. Because this policy did not include any regulations to promote smoking cessation, it is unlikely to have influenced the reduction in hospitalizations among children whose parents smoked. The smoking proportion would not be associated with the effect of the second policy reduced hospitalizations for asthma among children whose parents had smoking habits. The Tokyo Metropolitan Government implemented an ordinance on April 1, 2018, that required parents to make an effort to prevent their children from being exposed to passive smoking at home, with no penalties. However, no significant changes were observed in the percentage of households with smoke-free rules after the ordinance was implemented [ 26 ]. Another study revealed that the ordinance was not associated with changes in smoking behavior, suggesting that smoking may have shifted from public facilities to private spaces, such as homes [ 27 ]. These findings indicate that policies without penalties, whether they are ordinances or national laws, may not effectively change smoking behavior in private spaces. Given that the first policy lacked wide recognition and had no penalties or enforcement, the government might have benefited from implementing broader public awareness campaigns and introducing penalties to make the policy more effective. We acknowledge some limitations of this study that should be considered when interpreting the results. First, it was difficult to estimate the overall impact of the policy because the third step of policy implementation in April 2020 coincided with the coronavirus pandemic. In addition, it was difficult to estimate the exact impact during the period affected by the coronavirus pandemic. However, if we analyze data from more recent years following the COVID-19 pandemic, different results may be observed. Further research using longer-term data is needed to accurately estimate the overall impact of the policy. Second, it is possible that some local governments enacted their own unique policies on public smoking in addition to the policy enacted by the national government, which may have affected the results. Third, this database includes three types of insurers, and a previous study confirmed the population representativeness of the database [ 28 ]. However, there was a difference between this study and the surveys conducted by the MHLW [ 13 , 23 ] regarding the proportions of individuals who smoke. This difference may influence the occurrence of patients whose parents had smoking habits. Therefore, the results from this study should be interpreted with caution because of the limited generalizability. Finally, the short intervals between the first, second, and third policy implementations may have affected the estimation of trends, seasonality, and autocorrelation. Conclusion Our study suggests that the policies introduced in February and July 2019 in Japan were not associated with decreases in hospitalization or prescribed medication for severe asthma in outpatient settings. The policy introduced in July 2019 was associated with a reduction in hospitalizations for asthma among children whose parents had smoking habits. However, further research using long-term data is needed to appropriately estimate the overall impact of the policy. Declarations Conflicts of interest The first author is affiliated with the Ministry of Health, Labor, and Welfare in Japan at the time of submission. Ethics approval This study was approved by the Institutional Review Board of the University of Tokyo (No. 3501-(5); May 19, 2021). Consent to participate The requirement for written consent was waived owing to data anonymity. Consent for publication Not applicable Competing Interests TM is affiliated with the Ministry of Health, Labor, and Welfare in Japan at the time of submission.YS receives the research funding from DeSC Healthcare Inc. Funding This work was supported by a grant from the Ministry of Health, Labour and Welfare, Japan (23AA2003). Author Contribution Takahito Morita: Conceptualization, Data curation, Formal analysis, Methodology, Writing – original draft. Yusuke Sasabuchi: Formal analysis, Supervision, Writing – review and editing. Hideo Yasunaga: Funding acquisition, Supervision, Writing – review and editing. Acknowledgement This work was supported by a grant from the Ministry of Health, Labour and Welfare, Japan (23AA2003). Data Availability The requirement for written consent was waived due to data anonymity. References Strachan DP, Cook DG. Health effects of passive smoking. 6. Parental smoking and childhood asthma: longitudinal and case-control studies. 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Zhong X, Xiao LH, Wang DL, Yang SW, Mo LF, He LF, et al. Impact of a quality control circle on the incidence of catheter-associated urinary tract infection: an interrupted time series analysis. Am J Infect Control. 2020;48(10):1184–8. 10.1016/j.ajic.2020.01.006 . Turner SL, Forbes AB, Karahalios A, Taljaard M, McKenzie JE. Evaluation of statistical methods used in the analysis of interrupted time series studies: a simulation study. BMC Med Res Methodol. 2021;21(1):181. 10.1186/s12874-021-01364-0 . Ministry of Foreign Affairs. Basic Policies for Novel Coronavirus Disease Control. 2020. Available from: https://www.mofa.go.jp/files/100045102.pdf . Accessed 2025 May 22. Ministry of Health, Labour and Welfare. The national health and nutrition survey in Japan, 2019 (in Japanese). 2020b. Available from: https://www.mhlw.go.jp/content/001066903.pdf . Accessed 2025 Jan 18. National Cancer Center Japan. The report of World No-Tobacco Day public opinion poll in 2023 (in Japanese). 2023. Available from: https://www.ncc.go.jp/jp/icc/cancer-info/project/tabacco/20230531.pdf . Accessed 2025 Jan 18. Ministry of Health, Labour and Welfare. The summary of the survey result about the smoking environment in 2021 (in Japanese). 2021. Available from: https://www.mhlw.go.jp/content/10900000/001043203.pdf . Accessed 2025 Jan 18. Umeki Y, Tabuchi T. Effects of ordinances prohibiting smoking in private homes with children following smoke-free household rules in Tokyo. Nihon Koshu Eisei Zasshi. 2021;68(12):914–24. 10.11236/jph.21-051 . Zeng S, Noguchi H, Shimokawa S. Partial smoking ban and secondhand smoke exposure in Japan. Int J Environ Res Public Health. 2019;16(15):2804. 10.3390/ijerph16152804 . Okada A, Yasunaga H. Prevalence of noncommunicable diseases in Japan using a newly developed administrative claims database covering young, middle-aged, and elderly people. JAMA. 2022;5:190–8. Additional Declarations Competing interest reported. TM is affiliated with the Ministry of Health, Labor, and Welfare in Japan at the time of submission. YS receives the research funding from DeSC Healthcare Inc. Supplementary Files SupplementalMaterials.doc Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6917732","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":515912416,"identity":"2895d42e-8cab-4aab-b921-be38ff2fb18c","order_by":0,"name":"Takahito Morita","email":"data:image/png;base64,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","orcid":"","institution":"The University of Tokyo","correspondingAuthor":true,"prefix":"","firstName":"Takahito","middleName":"","lastName":"Morita","suffix":""},{"id":515912419,"identity":"252417dc-a9f0-4d8c-9e84-e9eb07315fef","order_by":1,"name":"Yusuke Sasabuchi","email":"","orcid":"","institution":"The University of Tokyo","correspondingAuthor":false,"prefix":"","firstName":"Yusuke","middleName":"","lastName":"Sasabuchi","suffix":""},{"id":515912423,"identity":"4a8822f8-77d1-4fff-b5fe-357c10820ceb","order_by":2,"name":"Hideo Yasunaga","email":"","orcid":"","institution":"The University of Tokyo","correspondingAuthor":false,"prefix":"","firstName":"Hideo","middleName":"","lastName":"Yasunaga","suffix":""}],"badges":[],"createdAt":"2025-06-17 23:53:13","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6917732/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6917732/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":102745582,"identity":"f9f660f9-0cb6-4c7f-9b10-d3a4f0f0fb5c","added_by":"auto","created_at":"2026-02-16 08:52:07","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1321258,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6917732/v1/adebaf36-6f95-4d0e-b351-7b2670b748f7.pdf"},{"id":91640329,"identity":"7a33c10b-6786-40af-9c7f-bb0f7016d1f2","added_by":"auto","created_at":"2025-09-18 14:42:13","extension":"doc","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":6212096,"visible":true,"origin":"","legend":"","description":"","filename":"SupplementalMaterials.doc","url":"https://assets-eu.researchsquare.com/files/rs-6917732/v1/b04af0bb57773e07ea4c74c1.doc"}],"financialInterests":"Competing interest reported. TM is affiliated with the Ministry of Health, Labor, and Welfare in Japan at the time of submission.\nYS receives the research funding from DeSC Healthcare Inc.","formattedTitle":"Changes in the occurrence of children’s asthma after the 2019 revision of the Health Promotion Act preventing passive smoking in Japan: interrupted time-series analyses","fulltext":[{"header":"Background","content":"\u003cp\u003ePassive smoking contributes to serious health problems in children [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e], including asthma and sudden infant death syndrome (SIDS). More than 70% of children up to 3-years-old and more than 80% of those up to six-years-old have asthma [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. The incidence of SIDS is estimated to be 1 in every 6,000\u0026ndash;7,000 births in Japan [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. The incidence of asthma and SIDS is reported to be closely related to passive smoking [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Passive smoking is recognized as a major risk factor in parenting environments [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. The incidence of SIDS is 1.5 times higher when the father smokes at home after the birth of his child [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Another study reported that the incidence of asthma in children aged 5 to 16 years was 23% higher in those exposed to passive smoking [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eSeveral countries have introduced smoke-free policies to prevent passive smoking. A study in Scotland reported a reduction in the proportion of hospitalizations for childhood asthma following the introduction of the smoke-free policy in 2006 [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Another study in Arizona found that the statewide smoking ban was associated with a reduction in asthma-related hospitalizations, particularly in counties without previous ban regulations [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. A meta-analysis showed that smoke-free laws were followed by fewer hospitalizations, and comprehensive regulations banning smoking in workplaces, restaurants, and bars were associated with a greater impact [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eIn Japan, the Health Promotion Act was revised on July 25, 2018, strengthening regulations against passive smoking to protect individuals, including children. To prevent passive smoking, the new regulation prohibits smoking in facilities used by the public and commercial means of passenger transportation, except in specified areas, and establishes measures to be taken by the managing authorities of these facilities [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. The regulation served three purposes: to eliminate unwanted passive smoking, to protect children and vulnerable individuals from passive smoking, and to implement measures specific to the type and location of facilities. The regulation took effect in three phases. The first, which took effect on January 24, 2019, required the government to take action against passive smoking and mandated that all smokers consider their surroundings when smoking, even at home. The second step, which took effect on July 1, 2019, required smoke-free premises at facilities primarily used by vulnerable individuals, such as schools, hospitals, and child welfare facilities. The third measure, which took effect on April 1, 2020, established a general indoor smoking ban across all public facilities and transportation systems [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eA survey conducted by the Ministry of Health, Labour and Welfare of Japan (MHLW) in 2022 on smoking environments revealed that compliance with the complete smoking ban in schools, child welfare facilities, medical institutions, and administrative agencies increased from 85.9% in 2019 to 87.4% in 2021 [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. However, this survey did not assess the impact of this regulation on smoking practices at home. Another survey conducted in Osaka City in 2022 found that only 25% of parents who smoke at home refrained from smoking in front of their elementary school-aged children [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. Despite the increased enforcement of smoking bans in facilities primarily used by individuals vulnerable to passive smoking, many children continued to be exposed to it at home. Thus, it remains unclear whether the regulation has had a positive impact on children\u0026rsquo;s health in Japan. Therefore, we conducted an interrupted time-series analysis to evaluate the impact of the policy aimed at protecting children from passive smoking on the occurrence of severe asthma and SIDS.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003eThis study was approved by the Institutional Review Board of the University of Tokyo (No. 3501-(5); May 19, 2021). Since the data were anonymized, the requirement for written consent was waived. Clinical trial number: not applicable\u003c/p\u003e\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003eData source\u003c/h2\u003e\u003cp\u003eWe accessed the DeSC database (DeSC Healthcare Inc.), which comprises commercially available administrative claims and health checkup data, for the period between April 2014 and November 2022. This database includes information for approximately 12,500,000 individuals and health insurance claims data from three types of health insurers: (1) Health Insurance for employees of large companies, (2) National Health Insurance for the unemployed and individual proprietors, and (3) the Advanced Elderly Medical Service System for individuals aged 75 years or older. The claim data at the individual level is stored anonymously. The database includes data on infants, younger individuals, and older individuals, and contains the following information: family identifier; individual identifier; birth month; sex; duration of insurance; diagnosis encoded according to the International Classification of Diseases, 10th Revision (ICD-10); and drugs dispensed based on the Anatomical Therapeutic Chemical Classification System. In addition, the database contains information on the annual health checkup information for approximately 30% of the entire population. The annual health checkup data comprise health status, mental health status, dietary habits, oral function, weight change, physical function and falls, cognitive function, smoking, social engagement, and social support, assessed through a self-administered questionnaire [\u003cspan additionalcitationids=\"CR16\" citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. The annual health checkup is voluntary and focuses on metabolic syndrome for individuals aged 40 to 74 years to prevent lifestyle-related diseases. The smoking section of the questionnaire includes the following question: \u0026ldquo;Are you currently a heavy smoker?\u0026rdquo; (\u0026ldquo;A heavy smoker\u0026rdquo; refers to those who have smoked over 100 cigarettes in their lifetime, and have smoked over a period of six months, including in the past month) [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e].\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003ePatients and outcomes\u003c/h3\u003e\n\u003cp\u003eWe included all children aged younger than six years in our analyses. The measured outcomes were the monthly occurrences of SIDS and severe asthma per 100,000 children. SIDS was defined according to the ICD-10 codes presented in Supplementary Table\u0026nbsp;1. Severe asthma was defined as either hospitalization for asthma or medications prescribed during outpatient treatment [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e], as listed in Supplementary Tables\u0026nbsp;1 and 2. For each month in the study period, we calculated the outcomes as the number of occurrences among all children registered in the claims data for that month.\u003c/p\u003e\n\u003ch3\u003eVariables\u003c/h3\u003e\n\u003cp\u003eThe baseline characteristics of children who had died from SIDS or had severe asthma included age, sex, fiscal year, and the smoking habits of their parents. We determined the smoking status of their parents using health checkup data from April 2017 to March 2022.\u003c/p\u003e\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e\u003ch2\u003eStatistical analysis\u003c/h2\u003e\u003cp\u003eFirst, we described the background characteristics of patients, stratified by the type of outcomes: SIDS, hospitalizations for asthma, and outpatient medication for severe asthma. Second, we created aggregated monthly data from May 2018 to March 2020 for the interrupted time-series analysis. Data were used to evaluate the impact of the policy that took effect on January 24, 2019, and July 1, 2019, assessed as \u0026ldquo;February 2019\u0026rdquo; and \u0026ldquo;July 2019,\u0026rdquo; respectively. A Prais\u0026ndash;Winsten linear regression model was fitted to account for autocorrelation [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e], and we analyzed the impact of the policy by estimating the following segmented regression model [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]:\u003c/p\u003e\u003cp\u003e\u003cem\u003eY\u003c/em\u003e\u003csub\u003e\u003cem\u003et\u003c/em\u003e\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;\u003cem\u003eβ\u003c/em\u003e\u003csub\u003e\u003cem\u003e0\u003c/em\u003e\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;\u003cem\u003eβ\u003c/em\u003e\u003csub\u003e\u003cem\u003e1\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003et\u003c/em\u003e\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;\u003cem\u003eβ\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eX\u003c/em\u003e\u003csub\u003e\u003cem\u003e1t\u003c/em\u003e\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;\u003cem\u003eβ\u003c/em\u003e\u003csub\u003e\u003cem\u003e3\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003et\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eX\u003c/em\u003e\u003csub\u003e\u003cem\u003e1t\u003c/em\u003e\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;\u003cem\u003eβ\u003c/em\u003e\u003csub\u003e\u003cem\u003e4\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eX\u003c/em\u003e\u003csub\u003e\u003cem\u003e2t\u003c/em\u003e\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;\u003cem\u003eβ\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003et\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eX\u003c/em\u003e\u003csub\u003e\u003cem\u003e2t\u003c/em\u003e\u003c/sub\u003e\u003c/p\u003e\u003cp\u003ewhere \u003cem\u003eY\u003c/em\u003e\u003csub\u003e\u003cem\u003et\u003c/em\u003e\u003c/sub\u003e is the monthly proportion of the outcome at time \u003cem\u003et\u003c/em\u003e; \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003et\u003c/em\u003e\u003c/sub\u003e is the number of months elapsed from the start of the observation period; \u003cem\u003eX\u003c/em\u003e\u003csub\u003e\u003cem\u003e1t\u003c/em\u003e\u003c/sub\u003e is a dummy variable (taking values 0 and 1 for before and after the introduction of the first policy in February 2019, respectively); \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003et\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eX\u003c/em\u003e\u003csub\u003e\u003cem\u003e1t\u003c/em\u003e\u003c/sub\u003e is the interaction term that indicates the months elapsed since the introduction of the first policy; \u003cem\u003eX\u003c/em\u003e\u003csub\u003e\u003cem\u003e2t\u003c/em\u003e\u003c/sub\u003e is a dummy variable (taking values 0 and 1 for before and after the introduction of the second policy in July 2019, respectively); \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003et\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eX\u003c/em\u003e\u003csub\u003e\u003cem\u003e2t\u003c/em\u003e\u003c/sub\u003e is the interaction term that indicates the months elapsed since the introduction of the second revision; \u003cem\u003eβ\u003c/em\u003e\u003csub\u003e\u003cem\u003e0\u003c/em\u003e\u003c/sub\u003e indicates the baseline monthly proportion of the outcome; \u003cem\u003eβ\u003c/em\u003e\u003csub\u003e\u003cem\u003e1\u003c/em\u003e\u003c/sub\u003e indicates the slope of the monthly proportion of the outcome before the first introduction; \u003cem\u003eβ\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e indicates the level change in the monthly proportion of the outcome immediately after the first introduction; \u003cem\u003eβ\u003c/em\u003e\u003csub\u003e\u003cem\u003e3\u003c/em\u003e\u003c/sub\u003e indicates the slope change following the first introduction and represents the effect of the first intervention over time; \u003cem\u003eβ\u003c/em\u003e\u003csub\u003e\u003cem\u003e4\u003c/em\u003e\u003c/sub\u003e indicates the level change in the monthly proportion of the outcome immediately after the second introduction; \u003cem\u003eβ\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e indicates the slope change following the second introduction and represents the effect of the second intervention over time; \u003cem\u003eβ\u003c/em\u003e\u003csub\u003e\u003cem\u003e1\u003c/em\u003e\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;\u003cem\u003eβ\u003c/em\u003e\u003csub\u003e\u003cem\u003e3\u003c/em\u003e\u003c/sub\u003e indicates the slope after the first introduction; and \u003cem\u003eβ\u003c/em\u003e\u003csub\u003e\u003cem\u003e1\u003c/em\u003e\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;\u003cem\u003eβ\u003c/em\u003e\u003csub\u003e\u003cem\u003e3\u003c/em\u003e\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;\u003cem\u003eβ\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e indicates the slope after the second introduction.\u003c/p\u003e\u003cp\u003eAdditionally, the Durbin\u0026ndash;Watson test was used to evaluate the autocorrelation between data points in the generalized least squares regression model [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. Statistical significance was defined as p\u0026thinsp;\u0026lt;\u0026thinsp;.05. All analyses were performed using Stata/SE software (version 17.0; StataCorp, College Station, TX, USA). We did not analyze the impact of the policy that took effect on April 1, 2020 because we could not exclude the effects of the coronavirus pandemic in March.\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eSubgroup analysis\u003c/h3\u003e\n\u003cp\u003e We identified all children aged younger than six years whose parents had smoking habits by linking the unique identifier assigned to all parents and their children under the same insurer. This was based on our assumption of a possible association between the occurrence of SIDS and asthma in children and smoking environments, supported by previous studies indicating that passive smoking is a major risk factor [\u003cspan additionalcitationids=\"CR6\" citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Subsequently, we conducted the analyses in the same manner as the main analyses.\u003c/p\u003e\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\u003ch2\u003eSensitivity analysis\u003c/h2\u003e\u003cp\u003eWe tested the robustness of our results using an alternative time bandwidth from June 2019 to February 2020. The Government of Japan decided on emergency response measures and established a fundamental policy for addressing the coronavirus in February 2020 [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. In addition, we tested the robustness of our results by using either July 2018 or January 2019 as the sole intervention point, starting from April 2017. The Health Promotion Act was revised in July 2018, and it was assumed that government publicity campaigns were conducted and that preparations to prevent passive smoking in public institutions and public places were underway before full implementation in January 2019.\u003c/p\u003e\u003c/div\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e\u003ch2\u003eMain analysis\u003c/h2\u003e\u003cp\u003eWe identified 77,182 eligible patients, including 7 who died of SIDS, 6,638 who were hospitalized for asthma, and 70,537 who received medication for severe asthma in outpatient settings. The baseline characteristics of the children are presented in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. We excluded detailed information on SIDS to avoid raising concerns about the potential identifiability of individuals. Approximately 75% of those hospitalized for asthma were under 3-years-old, and there were more boys than girls. Approximately 78% of patients who received medication for severe asthma were aged three to six years, and there were more boys than girls.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eBaseline characteristics of patients\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"17\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c12\" colnum=\"12\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c13\" colnum=\"13\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c14\" colnum=\"14\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c15\" colnum=\"15\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c16\" colnum=\"16\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c17\" colnum=\"17\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePeriod\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"4\" nameend=\"c5\" namest=\"c2\"\u003e\u003cp\u003eOverall\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"4\" nameend=\"c9\" namest=\"c6\"\u003e\u003cp\u003eMay 2018\u0026ndash;Jan 2019\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"4\" nameend=\"c13\" namest=\"c10\"\u003e\u003cp\u003eFeb 2019\u0026ndash;Jun 2019\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"4\" nameend=\"c17\" namest=\"c14\"\u003e\u003cp\u003eJul 2019\u0026ndash;Mar 2020\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCharacteristics\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e\u003cp\u003eHospitalization for asthma\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e\u003cp\u003eMedication for severe asthma at outpatient settings\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e\u003cp\u003eHospitalization for asthma\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c9\" namest=\"c8\"\u003e\u003cp\u003eMedication for severe asthma at outpatient settings\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c11\" namest=\"c10\"\u003e\u003cp\u003eHospitalization for asthma\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c13\" namest=\"c12\"\u003e\u003cp\u003eMedication for severe asthma at outpatient settings\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c15\" namest=\"c14\"\u003e\u003cp\u003eHospitalization for asthma\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c17\" namest=\"c16\"\u003e\u003cp\u003eMedication for severe asthma at outpatient settings\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAll, n (%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e6,638\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e(100.0)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e70,537\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e(100.0)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e2,766\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e(100.0)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e29,000\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e(100.0)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e1,353\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e(100.0)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003e14,888\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\"\u003e\u003cp\u003e(100.0)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003e2,519\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c15\"\u003e\u003cp\u003e(100.0)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c16\"\u003e\u003cp\u003e26,649\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c17\"\u003e\u003cp\u003e(100.0)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAge (years), n (%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c9\" namest=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c13\" namest=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c17\" namest=\"c14\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1,128\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e(17.0)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e2,674\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e(3.8)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e460\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e(16.6)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e1,138\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e(3.9)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e268\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e(19.8)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003e630\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\"\u003e\u003cp\u003e(4.2)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003e400\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c15\"\u003e\u003cp\u003e(15.6)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c16\"\u003e\u003cp\u003e906\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c17\"\u003e\u003cp\u003e(3.4)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1,764\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e(26.6)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e6,333\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e(9.0)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e765\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e(27.7)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e2,745\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e(9.5)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e365\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e(27.0)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003e1,331\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\"\u003e\u003cp\u003e(8.9)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003e634\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c15\"\u003e\u003cp\u003e(25.2)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c16\"\u003e\u003cp\u003e2,257\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c17\"\u003e\u003cp\u003e(8.5)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1,133\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e(17.1)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e6,296\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e(8.9)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e463\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e(16.7)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e2,669\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e(9.2)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e240\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e(17.7)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003e1,314\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\"\u003e\u003cp\u003e(8.8)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003e430\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c15\"\u003e\u003cp\u003e(17.1)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c16\"\u003e\u003cp\u003e2,313\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c17\"\u003e\u003cp\u003e(8.7)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e929\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e(14.0)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e15,303\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e(21.7)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e379\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e(13.7)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e6,458\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e(22.3)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e183\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e(13.5)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003e3,170\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\"\u003e\u003cp\u003e(21.3)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003e367\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c15\"\u003e\u003cp\u003e(14.6)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c16\"\u003e\u003cp\u003e5,675\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c17\"\u003e\u003cp\u003e(21.3)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e701\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e(10.6)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e15,519\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e(22.0)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e263\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e(9.5)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e6,152\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e(21.2)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e127\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e(9.4)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003e3,216\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\"\u003e\u003cp\u003e(21.6)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003e311\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c15\"\u003e\u003cp\u003e(12.4)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c16\"\u003e\u003cp\u003e6,151\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c17\"\u003e\u003cp\u003e(23.1)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e557\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e(8.4)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e13,333\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e(18.9)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e245\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e(8.9)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e5,574\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e(19.2)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e102\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e(7.5)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003e2,696\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\"\u003e\u003cp\u003e(18.1)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003e210\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c15\"\u003e\u003cp\u003e(8.3)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c16\"\u003e\u003cp\u003e5,063\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c17\"\u003e\u003cp\u003e(19.0)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e426\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e(6.4)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e11,079\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e(15.7)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e191\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e(6.9)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e4,264\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e(14.7)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e68\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e(5.0)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003e2,531\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\"\u003e\u003cp\u003e(17.0)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003e167\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c15\"\u003e\u003cp\u003e(6.6)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c16\"\u003e\u003cp\u003e4,284\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c17\"\u003e\u003cp\u003e(16.1)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSex, n (%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c9\" namest=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c13\" namest=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c17\" namest=\"c14\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBoy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e3,969\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e(59.8)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e39,675\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e(56.2)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e1,646\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e(59.5)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e16,372\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e(56.5)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e822\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e(60.1)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003e8,325\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\"\u003e\u003cp\u003e(55.9)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003e1,501\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c15\"\u003e\u003cp\u003e(59.6)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c16\"\u003e\u003cp\u003e14,978\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c17\"\u003e\u003cp\u003e(56.2)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSmoking habits (parents), n (%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c9\" namest=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c13\" namest=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c17\" namest=\"c14\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eYes\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e795\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e(12.0)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e10,454\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e(14.8)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e363\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e(13.1)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e4,446\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e(15.3)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e155\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e(11.5)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003e2,225\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\"\u003e\u003cp\u003e(14.9)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003e277\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c15\"\u003e\u003cp\u003e(11.0)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c16\"\u003e\u003cp\u003e3,783\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c17\"\u003e\u003cp\u003e(14.2)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eThe change in the yearly smoking proportion is presented in Supplementary Fig.\u0026nbsp;1. The smoking proportion decreased from 17.0% in 2017 to 14.0% in 2018 and remained unchanged thereafter. Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e shows the monthly number of patients stratified by outcomes: the number of patients aged younger than six years and the monthly occurrence per 100,000 children. The total number of deaths from SIDS was seven, which is too small a number for an interrupted time-series analysis.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eThe monthly number and occurrence of patients between May 2018 and March 2020\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"6\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eTime (month, year)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eTotal population aged younger than six years, n\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003eHospitalization for asthma\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e\u003cp\u003eMedication for severe asthma at outpatient settings\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003en\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003e/100,000\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003en\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003e/100,000\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMay 2018\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e370,853\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e262\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e71\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e2,706\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e730\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eJune 2018\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e369,665\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e295\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e80\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e2,722\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e740\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eJuly 2018\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e368,557\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e304\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e82\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e2,767\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e750\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAugust 2018\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e367,144\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e334\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e91\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e2,566\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e700\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSeptember 2018\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e365,735\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e431\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e118\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e3,879\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e1060\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eOctober 2018\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e364,501\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e404\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e111\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e4,798\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e1320\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eNovember 2018\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e363,121\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e278\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e77\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e3,761\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e1040\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDecember 2018\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e361,818\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e236\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e65\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e3,470\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e960\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eJanuary 2019\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e360,486\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e222\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e62\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e2,331\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e650\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFebruary 2019\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e358,849\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e221\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e62\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e2,652\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e740\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMarch 2019\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e357,369\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e262\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e73\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e3,324\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e930\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eApril 2019\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e355,703\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e317\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e89\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e3,347\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e940\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMay 2019\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e354,120\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e287\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e81\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e2,798\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e790\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eJune 2019\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e352,406\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e266\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e75\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e2,767\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e790\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eJuly 2019\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e350,544\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e290\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e83\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e2,807\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e800\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAugust 2019\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e348,728\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e313\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e90\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e2,403\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e690\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSeptember 2019\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e346,696\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e418\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e121\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e3,660\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e1060\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eOctober 2019\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e344,628\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e379\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e110\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e3,991\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e1160\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eNovember 2019\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e342,720\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e267\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e78\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e3,567\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e1040\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDecember 2019\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e340,915\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e261\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e77\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e3,151\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e920\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eJanuary 2020\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e339,007\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e210\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e62\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e2,296\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e680\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFebruary 2020\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e337,369\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e244\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e72\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e2,707\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e800\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMarch 2020\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e335,433\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e137\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e41\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e2,067\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e620\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eThe results of the interrupted time-series analysis are presented in Tables\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e and \u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e, and Supplementary Figs.\u0026nbsp;2 and 3. The monthly occurrence showed no significant trend throughout the study periods for both hospitalization and prescribed medication for severe asthma. The slope changes after the introduction of the first and second policies were also not significant for either hospitalization or prescribed medication for severe asthma. Additionally, the level changes at the first and second policy introductions were not significant for either hospitalization or prescribed medication for severe asthma. The results of the sensitivity analyses using an alternative time bandwidth between June 2019 and February 2020 were similar to those of the main analyses. (Supplementary Tables\u0026nbsp;3 and 4; Supplementary Figs.\u0026nbsp;4 and 5). The results of the sensitivity analyses using July 2018 as the intervention point showed no significant trends in either hospitalization or prescribed medication for severe asthma throughout the study periods. Supplementary Tables\u0026nbsp;5 and 6, and Supplementary Figs.\u0026nbsp;6 and 7. The sensitivity analyses using January 2019 as the intervention point also showed no significant trends except for the slope after the policy introduction. (Supplementary Tables\u0026nbsp;7 and 8, and Supplementary Figs.\u0026nbsp;8 and 9).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eMonthly changes in the occurrence among patients aged younger than six years who were hospitalized for asthma between May 2018 and March 2020\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"5\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eThe monthly occurrence among patients aged younger than six years who were hospitalized for asthma between May 2018 and March 2020 using the interrupted time-series analysis\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCoefficient\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e95% confidence interval\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eP\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSlope before the first policy introduction\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e-1.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e-6.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e4.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e.71\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eLevel change after the first policy introduction\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e-4.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e-31.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e21.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e.70\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSlope change of the first policy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e4.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e-6.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e1.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e.37\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSlope after the first policy introduction\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e4.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e-4.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e1.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e.31\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eLevel change after the second policy introduction\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e11.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e-28\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e5.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e.55\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSlope change of the second policy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e-9.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e-21.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e1.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e.08\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSlope after the second policy introduction\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e-6.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e-13.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e.07\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eMonthly changes in the occurrence among patients aged younger than six years who received medication for severe asthma at outpatient settings between May 2018 and March 2020\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"5\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eThe monthly occurrence among patients aged younger than six years who received medication for severe asthma at outpatient settings between May 2018 and March 2020 using the interrupted time-series analysis\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCoefficient\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e95% confidence interval\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eP\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSlope before the first policy introduction\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e15.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e-57.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e87.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e.67\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eLevel change after the first policy introduction\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e-33.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e-413.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e347.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e.86\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSlope change of the first policy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e-23.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e-156.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e110.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e.72\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSlope after the first policy introduction\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e-8.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e-84.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e67.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e.82\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eLevel change after the second policy introduction\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e82.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e-221.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e386.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e.57\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSlope change of the second policy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e-16.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e-118.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e86.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e.74\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSlope after the second policy introduction\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e-24.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e-78.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e30.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e.35\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\u003ch2\u003eSubgroup analysis\u003c/h2\u003e\u003cp\u003eWe identified 11,249 eligible patients whose parents had smoking habits, including 795 who were hospitalized for asthma and 10,454 who received medication for severe asthma. The baseline characteristics of the patients are presented in Supplementary Table\u0026nbsp;9. Supplementary Table\u0026nbsp;10 shows the monthly number of patients aged younger than six years and the monthly occurrence per 100,000 children.\u003c/p\u003e\u003cp\u003eThe results of the interrupted time-series analysis regarding hospitalization for asthma are presented in Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e and Supplementary Fig.\u0026nbsp;10. The results were similar to those of the main analyses, except for the slope after the introduction of the second policy. Hospitalization for asthma showed a decreasing trend after the introduction of the second policy for the subgroup of children whose parents had smoking habits. The results of the interrupted time-series analysis regarding prescribed medication for severe asthma were similar to those of the main analyses presented in Table\u0026nbsp;\u003cspan refid=\"Tab6\" class=\"InternalRef\"\u003e6\u003c/span\u003e and Supplementary Fig.\u0026nbsp;11.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab5\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eMonthly changes in the occurrence among patients aged younger than six years who were hospitalized for asthma and whose parents had smoking habits between May 2018 and March 2020\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"5\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eThe monthly occurrence among patients aged younger than six years who were hospitalized for asthma whose parents had smoking habits between May 2018 and March 2020 using the interrupted time-series analysis\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCoefficient\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e95% confidence interval\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eP\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSlope before the first policy introduction\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e-3.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e-13.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e7.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e.54\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eLevel change after the first policy introduction\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e-11.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e-83.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e61.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e.75\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSlope change of the first policy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e4.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e-17.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e26.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e.67\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSlope after the first policy introduction\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e1.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e-14.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e17.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e.86\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eLevel change after the second policy introduction\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e38.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e-37.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e114.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e.30\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSlope change of the second policy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e-12.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e-31.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e6.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e.17\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSlope after the second policy introduction\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e-11.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e-21.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e-2.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e.02\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"5\"\u003eDurbin\u0026ndash;Watson statistic (original)\u0026thinsp;=\u0026thinsp;1.41; Durbin\u0026ndash;Watson statistic (transformed)\u0026thinsp;=\u0026thinsp;1.73\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab6\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 6\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eMonthly changes in the occurrence among patients aged younger than six years who received medication for severe asthma at outpatient settings and whose parents had smoking habits between May 2018 and March 2020\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"5\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eThe monthly occurrence among patients aged younger than six years who received medication for severe asthma at outpatient settings and whose parents had smoking habits between May 2018 and March 2020 using the interrupted time-series analysis\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCoefficient\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e95% confidence interval\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eP\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSlope before the first policy introduction\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e23.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e-138.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e183.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e.77\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eLevel change after the first policy introduction\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e53.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e-801.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e906.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e.90\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSlope change of the first policy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e-93.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e-375.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e188.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e.50\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSlope after the first policy introduction\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e-70.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e-220.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e80.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e.34\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eLevel change after the second policy introduction\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e267.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e-287.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e820.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e.32\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSlope change of the second policy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e20.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e-173.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e214.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e.83\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSlope after the second policy introduction\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e-50.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e-136.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e35.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e.23\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"5\"\u003eDurbin\u0026ndash;Watson statistic (original)\u0026thinsp;=\u0026thinsp;1.31; Durbin\u0026ndash;Watson statistic (transformed)\u0026thinsp;=\u0026thinsp;1.65\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eUsing the DeSC database, we examined the impact of policies that prevent children from passive smoking on the occurrence of SIDS and severe asthma. The occurrence of SIDS was rare. An interrupted time-series analysis revealed that neither the first policy introduced in February 2019 nor the second introduced in July 2019 was associated with a decrease in hospitalization or outpatient medication for severe asthma. However, the second policy was associated with a decrease in hospitalizations for asthma among children whose parents had smoking habits. In addition, the interrupted time-series analysis revealed that the policy introduced in July 2018 was not associated with a decrease in hospitalizations or outpatient medications for severe asthma.\u003c/p\u003e\u003cp\u003eAccording to surveys by the MHLW, the proportions of individuals with daily smoking habits were 16.4% in 2018 and 15.8% in 2019 [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. The smoking proportions in this study were similar.\u003c/p\u003e\u003cp\u003eThe February 2019 policy required the government to take action against unwanted passive smoking and for individuals to consider their surroundings when smoking. The first policy was not associated with a decrease in hospitalization or outpatient medication for severe asthma. This lack of impact may be due to smokers being unaware of the regulation at the time of its introduction. According to a survey by the National Cancer Center Japan in 2023, 65.2% of all respondents over 20 years of age were unaware that the Health Promotion Act had been revised and that the policy against passive smoking had been strengthened, despite the fact that three years had passed since the revision [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. In addition, the first policy may not have had an impact because it lacked penalties or enforcement.\u003c/p\u003e\u003cp\u003eThe second policy introduced in July 2019 required facilities primarily used by individuals vulnerable to passive smoking, such as schools, hospitals, and child welfare facilities, to be smoke-free. The second policy was also not associated with a decrease in the occurrence of hospitalizations or outpatient medication for severe asthma. This lack of impact may be because most of the facilities subject to the regulation had already banned smoking by the time the second policy was introduced. As previously noted, the MHLW survey found only a marginal increase in compliance with the complete smoking ban among schools, child welfare facilities, medical institutions, and administrative agencies [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eThe second policy was associated with reduced hospitalizations for asthma among children whose parents had smoking habits. According to a survey by the National Cancer Center Japan in 2023, 60.7% of individuals older than 20 years who smoke were aware that the Health Promotion Act had been revised and that the policy on passive smoking had been strengthened [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. In addition to the findings from the survey, the proportion of smoke-free facilities remained unchanged at 84.9% in 2020 and 86.9% in 2021 [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. There are few opportunities for passive smoking outdoors, including in streets and parks in Japan, as some local governments have enacted bans on public smoking. In fact, according to a survey by the MHLW in 2019, 2% of all respondents over 20-years-old were exposed to passive smoking daily on the streets, and 0.3% were exposed in outdoor areas frequently used by children, including schools and parks [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. Therefore, considering the limited opportunities for passive smoking outdoors in the three years following the introduction of the second policy, parents who smoke and have children with asthma may have become more aware of passive smoking outdoors since that policy was implemented.\u003c/p\u003e\u003cp\u003eIn addition, the smoking proportion presented in Supplementary Fig.\u0026nbsp;1 remained unchanged after 2018 and slightly increased from 2019 to 2020. Because this policy did not include any regulations to promote smoking cessation, it is unlikely to have influenced the reduction in hospitalizations among children whose parents smoked. The smoking proportion would not be associated with the effect of the second policy reduced hospitalizations for asthma among children whose parents had smoking habits. The Tokyo Metropolitan Government implemented an ordinance on April 1, 2018, that required parents to make an effort to prevent their children from being exposed to passive smoking at home, with no penalties. However, no significant changes were observed in the percentage of households with smoke-free rules after the ordinance was implemented [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. Another study revealed that the ordinance was not associated with changes in smoking behavior, suggesting that smoking may have shifted from public facilities to private spaces, such as homes [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. These findings indicate that policies without penalties, whether they are ordinances or national laws, may not effectively change smoking behavior in private spaces.\u003c/p\u003e\u003cp\u003eGiven that the first policy lacked wide recognition and had no penalties or enforcement, the government might have benefited from implementing broader public awareness campaigns and introducing penalties to make the policy more effective.\u003c/p\u003e\u003cp\u003eWe acknowledge some limitations of this study that should be considered when interpreting the results. First, it was difficult to estimate the overall impact of the policy because the third step of policy implementation in April 2020 coincided with the coronavirus pandemic. In addition, it was difficult to estimate the exact impact during the period affected by the coronavirus pandemic. However, if we analyze data from more recent years following the COVID-19 pandemic, different results may be observed. Further research using longer-term data is needed to accurately estimate the overall impact of the policy. Second, it is possible that some local governments enacted their own unique policies on public smoking in addition to the policy enacted by the national government, which may have affected the results. Third, this database includes three types of insurers, and a previous study confirmed the population representativeness of the database [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. However, there was a difference between this study and the surveys conducted by the MHLW [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e] regarding the proportions of individuals who smoke. This difference may influence the occurrence of patients whose parents had smoking habits. Therefore, the results from this study should be interpreted with caution because of the limited generalizability. Finally, the short intervals between the first, second, and third policy implementations may have affected the estimation of trends, seasonality, and autocorrelation.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eOur study suggests that the policies introduced in February and July 2019 in Japan were not associated with decreases in hospitalization or prescribed medication for severe asthma in outpatient settings. The policy introduced in July 2019 was associated with a reduction in hospitalizations for asthma among children whose parents had smoking habits. However, further research using long-term data is needed to appropriately estimate the overall impact of the policy.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eConflicts of interest\u003c/h2\u003e\n\u003cp\u003eThe first author is affiliated with the Ministry of Health, Labor, and Welfare in Japan at the time of submission.\u003c/p\u003e\n\u003ch2\u003eEthics approval\u003c/h2\u003e\n\u003cp\u003eThis study was approved by the Institutional Review Board of the University of Tokyo (No. 3501-(5); May 19, 2021).\u003c/p\u003e\n\u003ch2\u003eConsent to participate\u003c/h2\u003e\n\u003cp\u003eThe requirement for written consent was waived owing to data anonymity.\u003c/p\u003e\n\u003ch2\u003eConsent for publication\u003c/h2\u003e\n\u003cp\u003eNot applicable\u003c/p\u003e\n\u003ch2\u003eCompeting Interests\u003c/h2\u003e\n\u003cp\u003eTM is affiliated with the Ministry of Health, Labor, and Welfare in Japan at the time of submission.YS receives the research funding from DeSC Healthcare Inc.\u003c/p\u003e\n\u003ch2\u003eFunding\u003c/h2\u003e\n\u003cp\u003eThis work was supported by a grant from the Ministry of Health, Labour and Welfare, Japan (23AA2003).\u003c/p\u003e\n\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\n\u003cp\u003eTakahito Morita: Conceptualization, Data curation, Formal analysis, Methodology, Writing \u0026ndash; original draft. Yusuke Sasabuchi: Formal analysis, Supervision, Writing \u0026ndash; review and editing. Hideo Yasunaga: Funding acquisition, Supervision, Writing \u0026ndash; review and editing.\u003c/p\u003e\n\u003ch2\u003eAcknowledgement\u003c/h2\u003e\n\u003cp\u003eThis work was supported by a grant from the Ministry of Health, Labour and Welfare, Japan (23AA2003).\u003c/p\u003e\n\u003ch2\u003eData Availability\u003c/h2\u003e\n\u003cp\u003eThe requirement for written consent was waived due to data anonymity.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eStrachan DP, Cook DG. Health effects of passive smoking. 6. Parental smoking and childhood asthma: longitudinal and case-control studies. 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JAMA. 2022;5:190\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"passive smoking, asthma, hospitalization, smoking habits, Japan","lastPublishedDoi":"10.21203/rs.3.rs-6917732/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6917732/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eAim\u003c/h2\u003e\u003cp\u003ePassive smoking contributes to serious health problems in children, including asthma and sudden infant death syndrome. In Japan, the Health Promotion Act was revised in February and July 2019, and regulations against passive smoking were strengthened to protect children. We evaluated the impact of the policy, which had remained unexamined.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e\u003cp\u003eWe used the DeSC database in Japan. We included all children under the age of six years. Interrupted time-series analyses were conducted by fitting Prais\u0026ndash;Winsten linear regression models to assess the association of the policy revisions with the outcomes, namely the monthly occurrence per 100,000 children of hospitalization or outpatient medication for severe asthma between May 2018 and March 2020.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e\u003cp\u003eNeither the first revision in February 2019 nor the second in July 2019 was associated with a decrease in hospitalization for asthma or outpatient medication for severe asthma. The second policy was associated with a reduction in hospitalization for asthma among children whose parents had smoking habits.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e\u003cp\u003eOur findings show that the revised policies introduced in Japan did not decrease the occurrence of severe asthma in children. This can be attributed to a lack of awareness about the first policy among the public and only a marginal increase in compliance following the second revision among institutions serving vulnerable populations. This suggests that the Japanese government should implement measures to increase awareness of the policy and enforce strict repercussions for non-compliance.\u003c/p\u003e","manuscriptTitle":"Changes in the occurrence of children’s asthma after the 2019 revision of the Health Promotion Act preventing passive smoking in Japan: interrupted time-series analyses","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-09-18 14:42:08","doi":"10.21203/rs.3.rs-6917732/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"d7347819-a334-4db4-b0fa-3fd828ef3ebf","owner":[],"postedDate":"September 18th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-02-11T12:57:48+00:00","versionOfRecord":[],"versionCreatedAt":"2025-09-18 14:42:08","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6917732","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6917732","identity":"rs-6917732","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}