Weight Change from Early to Middle Adulthood and Incident Asthma Later in Life: A Retrospective Cohort Study

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This study aimed to investigate the association between weight change from early to middle adulthood and risk of incident asthma. Methods: Using data from the National Health and Nutrition Examination Survey (NHANES), we performed a nationally retrospective cohort study of the U.S. general population. A total of 20 771 people aged 40-74 years with recalled weight at young and middle adulthood were included in the cohort. Hazard ratios relating weight change to incident asthma over 10 years of follow-up were calculated using Cox models adjusting for covariates. Results: Compared with participants with stable non-obesity between young and middle adulthood, the hazard ratios of incident asthma were 1.63 (95% confidence interval 1.29 to 2.07) for weight gain (non-obesity to obesity), 1.41 (0.97 to 2.05) for stable obesity, and 1.21 (0.41 to 3.62) for weight loss (obesity to non-obesity). In addition, participants who gained more than 20 kg had a hazard ratio of 1.53 (1.15 to 2.03), compared with those whose weight had remained stable. When stratified by sex, the association between weight gain and incident asthma was seen only in females. Population attributable fraction calculations estimated that 10.2% of adult-onset asthma could be averted, if all those who were non-obesity at early adulthood could prevent weight gain by midlife. Conclusion: The findings implied that maintaining normal weight across adulthood, especially preventing weight gain in early adulthood, was important for preventing adult-onset asthma. Health Economics & Outcomes Research Pulmonology asthma body mass index obesity weight gain Figures Figure 1 Figure 1 Figure 2 Figure 2 Introduction Asthma and obesity are major public health problems that have increased in the past decades. From 1999 through 2018, the age-adjusted prevalence of obesity among adults increased from 30.5–42.4% in the United States.[ 1 ] Although asthma was less prevalent than obesity, it also increased from 7.1–9.2% between 2001 and 2014.[ 2 ] The increasing prevalence of asthma and obesity suggested an association between the two conditions. A meta-analysis of seven prospective studies involving more than 300 000 adults found a dose-response relationship between obesity and asthma: the odds ratio of incident asthma was 1.5 in the overweight and 1.9 in the obesity groups compared with the lean group.[ 3 ] Results from Mendelian Randomization studies provided causal evidence for obesity increasing the risk of asthma.[ 4 – 6 ] However, many previous cohort studies[ 7 – 10 ] included only a single measurement of BMI, which ignored the dynamic feature of body weight over time. Thus more studies are needed to assess the long term consequences of weight change during certain life periods. A meta-analysis including 147 252 European children in 31 birth cohort studies found that rapid weight gain in infancy was positively associated with childhood asthma.[ 11 ] The Taiwan Children Health Study in school-age children reported that rapid adiposity growth might increase risks of childhood asthma.[ 12 ] In contrast to childhood-onset asthma, less is known about the factors associated with adult-onset asthma, particularly from longitudinal studies.[ 13 ] Asthma that starts in adulthood differs from childhood-onset asthma in that it is often non-atopic, more severe and associated with a faster decline in lung function.[ 13 ] Excess adiposity tends to accrue during early and middle adulthood for most people. Adult weight gain has been associated with increased mortality risk, diabetes, hypertension, cardiovascular disease, several types of cancer, etc.[ 14 – 17 ] However, studies exploring the effect of weight change from early to middle adulthood on adult-onset asthma were limited. Therefore, this study aimed to examine the relations of weight changes from early (age 25 years) to middle adulthood (mean age 44 years) with asthma incidence in the United States. Methods Study Design and Population Details of National Health and Nutrition Examination Survey (NHANES) have been described elsewhere.[ 18 ] NHANES is a series of ongoing cross-sectional surveys conducted by the National Center for Health Statistics (NCHS) of the Centers for Disease Control and Prevention (CDC). Representative samples of the non-institutional U.S. population were selected by a complex stratified, multistage probability sampling design. NHANES was approved by the National Center for Health Statistics research ethics review board, and written informed consent from all the participants was provided during the survey. Because the data are publicly available and de-identified, institutional review board approval was not required for this analysis. This study used data across 9 cycles of the continuous NHANES (1999–2000 through 2015–2016) including adults aged 40–74 [15] at examination. We used recall questions on weight history and age at asthma diagnosis to create a retrospective cohort from the cross-sectional data. Specifically, self-reported weight change was assessed by participant recall of weight at age 25 and 10 years before the NHANES survey. We defined baseline as 10 years before the survey. Incident asthma was determined from respondents affirming that a health care provider had indicated a diagnosis of asthma. The reported age at diagnosis was used to establish the time of asthma onset. The design method for retrospective cohort study has been described in detail in a previous publication using NHANES data.[ 14 , 15 , 19 , 20 ] The study design was visually depicted in Figure S1. Participants who reported a date of onset that was before the initiation of follow-up were considered prevalent asthma cases and were excluded. We also excluded participants missing information of asthma diagnosis, those without diagnosis time and those without BMI at age 25 years and (or) at age 10 years before survey. Finally, a sample size of 20 771 individuals remained in our cohort for analysis (Figure S2). Assessments of weight change Data on weight at age 25 years and at 10 years before the NHANES survey were recalled. Measured height at the examination was used to calculate BMI, unless the participant was 50 years or older at the time of the survey. In this case, reported height at 25 was used to calculate BMI at 25, and measured height at the examination was used to calculate BMI at 10 years before the survey. [15] We categorized each of the two BMI variables into three groups: underweight and normal weight (< 25.0), overweight (25.0-29.9), and obesity (≥ 30.0). BMI change categories were then generated to capture weight change over the life course of an individual. We defined four weight change patterns based on BMI (kg/m 2 ) at age 25 and on BMI 10 years prior to the survey: stable non-obesity pattern (BMI age 25 <30 kg/m 2 and BMI 10 years prior <30) (reference group), non-obesity to obesity pattern (BMI age 25 <30 kg/m 2 and BMI 10 years prior ≥30), obesity to non-obesity pattern (BMI age 25 ≥30 kg/m 2 and BMI 10 years prior <30), stable obesity pattern (BMI age 25 ≥30 kg/m 2 and BMI 10 years prior ≥30). We also classified absolute weight change in each time interval into five groups: weight loss of at least 2.5 kg, weight change within 2.5 kg (reference group), weight gain of at least 2.5 kg but less than 10.0 kg, weight gain of at least 10 kg but less than 20.0 kg, and weight gain of at least 20.0 kg. These weight change categories were comparable with those used in previous studies.[ 14 – 16 ] Covariates Information on covariates was available through questionnaires, including age, sex, race/ethnicity (Mexican American, non-Hispanic white, non-Hispanic black, other), education level (less than high school, high school or equivalent, and college or above), family income-poverty ratio (≤ 1.3, ~ 1.85, ~ 3.0, and > 3.0), smoking status (ever and never smokers), and family history of asthma. Statistical analysis All analyses incorporated the sample weights, stratification, and clustering of the complex sampling design to ensure nationally representative estimates. Descriptive characteristics were computed through means and 95% confidence intervals for continuous variables and percentages for categorical and binary variables. We used Cox proportional hazards models with time in study as the underlying time metric to estimate the hazard ratio and corresponding 95% confidence intervals for incident asthma in relation to weight change patterns from age 25 years to 10 years before survey. For the main analyses, we examined the associations between the four weight change patterns and developing asthma. The stable non-obesity pattern was used as the reference to which all other weight change patterns were compared. We adjusted for baseline age, sex, and race/ethnicity in model 1. We further adjusted for education level, family income-poverty ratio level, smoking status, and family history of asthma in model 2. Dummy variables were used to indicate missing data for the covariates. Subgroup analyses and potential effect modifications were conducted by baseline age (< 50 and ≥ 50 years), sex, smoking status, and family history of asthma. A secondary analysis was implemented in which those who maintained a normal BMI during the time period were treated as a separate category of BMI change. In doing so, those originally in the stable non-obesity pattern were categorized into two new groups: 1) stable normal pattern (BMI age 25 <25.0 kg/m 2 and BMI 10 years prior <25.0), and 2) maximum overweight pattern (25.0-29.9 at either time but not ≥ 30.0 at the other time). Stable normal pattern was used as the reference category for this model. We also investigated the associations between absolute weight change groups and incident asthma risk, as well as the linear dose-response relation. For test of trend, we calculated the association with incident asthma by treating the categories of absolute weight change as ordinal variables. Finally, we calculated population attributable fractions (PAFs) of incident asthma owing to weight change using the following formula:[ 21 ] where p i is the proportion of weight change pattern i , HR i is the hazard ratio of incident asthma in weight change pattern i , and k is the total number of weight change patterns. A given PAF represents the proportion of incident asthmas that could be reduced if people with a particular weight change pattern were redistributed to another pattern and experienced the same relative risks as individuals in that new pattern. All statistical analyses were conducted in 2020 using SAS 9.4 (site 70239492) and R version 3.6.3. All P values were 2-tailed ( α = 0.05). Results Baseline characteristics and weight change pattern Table 1 reported characteristics of the sample with weighted estimates and unweighted sample sizes stratified by weight change category. The mean age of the sample was 44.2 years at baseline, and 50.7% were female. The study sample was 73.4% non-Hispanic white, 10.3% non-Hispanic black, 6.0% Mexican American, and 10.3% others. The mean BMI was 23.5 kg/m 2 at age 25, and 27.1 kg/m 2 at baseline. On average, participants gained 9.4 kg weight from age 25 years to baseline. Table 1 Characteristics of study participants in NHANES 1999–2016 according to weight change patterns from age 25 years to ten years before survey. a Characteristics Stable Non-obesity Non-obesity to Obesity Obesity to Non-obesity Stable Obesity Total Participants 15293 (75.2) 4015 (18.0) 209 (0.9) 1254 (5.9) 20771 Mean (95% CI) baseline age, years b 43.9 (43.6, 44.1) 46.9 (46.4, 47.3) 41.0 (39.7, 42.3) 41.4 (40.7, 42.1) 44.2 (44.0, 44.5) Female 7621 (52.0) 1965 (47.7) 83 (40.8) 598 (44.4) 10267 (50.7) Race/ethnicity Mexican American 2542 (5.6) 824 (7.0) 54 (8.4) 229 (7.4) 3649 (6.0) Non-Hispanic White 6854 (73.4) 1773 (74.4) 87 (70.5) 510 (70.5) 9224 (73.4) Non-Hispanic Black 3177 (9.7) 970 (11.4) 43 (11.8) 393 (15.6) 4583 (10.3) Other 2720 (11.4) 448 (7.2) 25 (9.3) 122 (6.4) 3315 (10.3) Education c Less than high school 4029 (16.0) 1160 (17.3) 82 (22.5) 348 (16.0) 5619 (16.3) High school or equivalent 3526 (23.4) 983 (26.0) 41 (19.6) 320 (27.0) 4870 (24.0) College or above 7730 (60.6) 1870 (56.7) 86 (57.8) 585 (57.0) 10271 (59.7) Family income-poverty ratio level c 0 ~ 1.3 3521 (15.0) 1017 (17.0) 75 (28.3) 359 (19.9) 4972 (15.8) ~ 1.85 1618 (8.0) 453 (9.4) 26 (10.2) 146 (10.7) 2243 (8.4) ~ 3 2448 (16.2) 727 (19.0) 32 (14.9) 219 (17.6) 3426 (16.8) > 3 6362 (60.8) 1496 (54.6) 67 (46.6) 430 (51.7) 8355 (59.0) Ever Smoker b 7286 (48.6) 1880 (48.4) 133 (62.5) 545 (43.3) 9844 (48.4) Family history of asthma 1668 (15.7) 534 (17.6) 27 (18.0) 198 (21.2) 2427 (16.4) Mean (95% CI) body mass index At age 25 years 22.1 (22.0, 22.2) 25.0 (24.8, 25.1) 34.0 (33.2, 34.8) 34.7 (34.4, 35.1) 23.5 (23.4, 23.6) At 10 years before survey 24.6 (24.5, 24.6) 34.0 (33.8, 34.1) 27.0 (26.5, 27.5) 38.8 (38.3, 39.3) 27.1 (27.0, 27.3) Mean (95% CI) absolute weight change, kg 6.2 (6.1, 6.4) 23.5 (22.9, 24.1) -19.1 (-22.2, -16.0) 10.5 (9.1, 11.9) 9.4 (9.1, 9.6) a All estimates accounted for complex survey designs. b At start of follow-up. c At end of follow-up Regarding life-course weight change, 75.2% of the participants were in the stable non-obesity group, 5.9% were in the stable obesity group, 18.0% of the participants moved from non-obesity to obesity and they gained 23.5 kg on average, whereas only 0.9% of the participants moved from the obesity to non-obesity category and they lost 19.1 kg on average. Relations of weight change patterns with incident asthma Among 20 771 participants, 627 had a diagnosis of asthma, yielding an overall incidence rate of 3.1 per 1000 person-years. Figure 1 presented cumulative incidence curves by time in study for each weight change group. Compared with stable non-obesity individuals, stable obesity participants had increased risks of incident asthma during the 10 years of follow-up, with hazard ratio of 1.41 (95% confidence interval 0.97 to 2.05) (Table 2 ). Moving from the non-obesity range at age 25 years to the obesity range at baseline was associated with a 63% higher risk of incident asthma (hazard ratio 1.63, 1.29 to 2.07). No significant difference (hazard ratio 1.21, 0.41 to 3.62) was observed in the risk of onset asthma between those changing from obesity to non-obesity and those who maintained stable non-obesity from young adulthood through midlife. The population attributable fractions were calculated to estimate the percentage of asthmas that could be averted under hypothetical scenarios. If those who gained weight from the non-obesity range at age 25 years to the obesity range at baseline had not gained weight, 10.2% of the adult-onset asthmas would have been averted in U.S. adults. Furthermore, 12.7% of the adult-onset asthmas would have been averted, if the total population had a stable non-obesity pattern from young adulthood through midlife. Table 2 Hazard ratios (95% CIs) of incident asthma with weight change patterns across adulthood in NHANES 1999–2016. a Weight Change Patterns No of incident asthma /person-years Model 1 b Model 2 c HR (95% CI) P HR (95% CI) P Category 1 d Stable Non-obesity 402/151360 1 1 Non-obesity to Obesity 165/39485 1.66 (1.30, 2.11) < 0.001 1.63 (1.29, 2.07) < 0.001 Obesity to Non-obesity 7/2067 1.47 (0.50, 4.27) 0.479 1.21 (0.41, 3.62) 0.730 Stable Obesity 53/12305 1.48 (1.02, 2.16) 0.041 1.41 (0.97, 2.05) 0.075 Category 2 e Weight loss ≥ 2.5 kg 33/11163 1.01 (0.60, 1.72) 0.964 0.91 (0.53, 1.56) 0.725 Weight change within 2.5 kg 126/48635 1 1 Weight gain ≥ 2.5 kg and < 10 kg 180/66293 0.95 (0.70, 1.30) 0.744 0.99 (0.73, 1.34) 0.938 Weight gain ≥ 10 kg and < 20 kg 139/46712 1.15 (0.85, 1.56) 0.372 1.19 (0.88, 1.60) 0.253 Weight gain ≥ 20 kg 149/32414 1.52 (1.14, 2.03) 0.005 1.53 (1.15, 2.03) 0.004 a All estimates accounted for complex survey designs. b Model 1 was adjusted for baseline age, sex, race/ethnicity. c Model 2 was additionally adjusted for education level, family income-poverty ratio level, smoking status, and family history of asthma. In the Category 2 analyses, we also included BMI at the age 25 years as potential confounders in model 2. d Stable Non-obesity, BMI age 25 <30 kg/m 2 and BMI 10 years prior <30; Non-obesity to Obesity, BMI age 25 <30 kg/m 2 and BMI 10 years prior ≥30; Obesity to Non-obesity, BMI age 25 ≥30 kg/m 2 and BMI 10 years prior <30; Stable Obesity, BMI age 25 ≥30 kg/m 2 and BMI 10 years prior ≥30. e Absolute weight change: weight loss of at least 2.5 kg, weight change within 2.5 kg, weight gain of at least 2.5 kg but less than 10.0 kg, weight gain of at least 10 kg but less than 20.0 kg, and weight gain of at least 20.0 kg. In the stratified analyses, the associations were stronger among participants who were more than 50 years old at baseline, female, never smoking, no family history of asthma compared with their counterparts (Fig. 2 ). However, we found no significant interactions with baseline age, sex, smoking status and family history of asthma. In the secondary analysis (Table S1), compared with the stable normal group, the maximum overweight group was not significantly associated with incident asthma risk (hazard ratio 1.19, 0.94 to 1.50); stable obesity had a hazard ratio of 1.52 (1.03 to 2.25) for incident asthma during the period; non-obesity to obesity pattern was consistently associated with highest incident asthma risk (hazard ratio 1.77, 1.35 to 2.32). Population attributable fraction calculation estimated that 21.8% of the adult-onset asthmas would have been averted, if the total population had a stable normal pattern from young adulthood through midlife. When evaluating the absolute weight changes, the hazard ratios for incident asthma in the extreme weight gain (weight gain ≥ 20 kg) group were 1.53 (1.15 to 2.03) from age 25 years to baseline, compared with the stable weight group (weight change within 2.5 kg) (Table 2 ). Moderate to large weight gain (weight gain ≥ 10 kg and < 20 kg), small to moderate weight gain (weight gain ≥ 2.5 kg and < 10 kg) and weight loss (more than 2.5 kg) were not significantly associated with incident asthma. Furthermore, we identified a linear dose-response association between absolute weight change across adulthood and risk of incident asthma ( P for trend = 0.024). These associations were independent of BMI at age 25 years. When we restricted the analysis to participants who had a BMI of < 25 at 25 years of age, results remained similar, suggesting that our estimates were not driven by participants with high BMIs who gained additional weight (data not shown). Discussion In this large retrospective cohort study of nationally representative U.S. adults, the highest risk of incident asthma was in participants who were weight gain (non-obesity to obesity) from early to middle adulthood; stable obesity across adulthood was also associated with increased risk of incident asthma. In addition, there was a dose-response effect of absolute weight gain on asthma incidence, independent of weight in early adulthood. The effects of weight gain on the annual odds of developing asthma were more pronounced in female than in male. The findings underscored the importance of prevention of weight gain in early adulthood, for reducing incident asthma risk in later life. Prior epidemiological data on the relationship between adulthood weight change and asthma were sparse. The California Teachers Study (CTS) including 88 304 women observed that weight gain ≥ 5 kg since age 18 years was statistically significantly associated with increased prevalence of adult-onset asthma.[ 22 ] However, weight gain did not clearly precede the observed asthma, these results may have simply reflected antecedent asthma followed by activity limitation and weight gain. By assessing weight change from the ages of 25 years to the baseline, the current study attempted to capture the changes in BMI during adulthood before the asthma starts, and to minimize reverse causation. In our study, weight gain from a non-obesity to an obesity pattern since young adulthood had a 63% higher incident asthma risk. Extreme weight gain (≥ 20 kg) from early to middle adulthood was associated with a 53% higher incident asthma risk. Higher weight gain predicted subsequent incident asthma in some,[ 23 – 25 ] but not all,[ 26 ] participants in the relevant prospective studies. Using data from the Nurses’ Health Study (NHS) with 85 911 female nurses aged 26–46 years at entry, Camargo et al. found that women who gained weight > 10 kg after age 18 were at significantly increased risk of developing asthma during the 4-year follow-up period.[ 23 ] Similarly, during a 3-year follow-up period of 67 229 women aged 40–65 years in the E3N Cohort Study, Romieu et al. reported that women who gained approximately ≥ 10 kg between the age of 20 years and baseline had a 89% increased risk of incident asthma.[ 25 ] Our results were consistent with these studies and indicated that avoiding obesity at young age and preventing weight gain from young to middle adulthood could be an important strategy to reduce future asthma risk. We also found evidence that weight gain was related to incident asthma in women but not men. A number of population-based studies have suggested that the relationship between obesity and asthma may be stronger in females.[ 27 , 28 ] Several possible mechanisms have been postulated to explain the obesity-asthma relationship. A sexual dimorphism exists in relation to body composition, in that females carry more fat subcutaneously and males carry more fat viscerally.[ 27 ] This led to distinct differences in the inflammatory pattern exhibited. For example, leptin is secreted more highly from subcutaneous adipose tissue and is therefore higher in females than males.[ 27 ] Compared to males, females have a smaller airway size relative to lung size.[ 23 ] An additional reduction in airway size caused by weight gain may disproportionately increase the susceptibility of females to asthma.[ 7 ] The increased estrogen levels associated with obesity are also thought to be one mechanism to explain the strong association between female obesity and adult-onset asthma. [28, 29] In our study, weight loss from young to middle adulthood was generally not significantly related to incident asthma compared with the stable normal group or stable obesity group. As weight loss from the obesity to the non-obesity among adulthood was rare, representing only 0.9% of the total population, and the results should be interpreted cautiously. More studies are needed to confirm the results in larger populations and explore the potential effect of weight loss among obesity people. Adults gain weight more rapidly from young to middle adulthood, and excess adiposity mostly accrues in this period compared with the period from middle to late adulthood when weight begins to stabilize or even decrease.[ 14 ] In addition, preventing weight gain from young to middle adulthood might be more important than promoting weight loss, because achieving long term weight loss and maintaining it are difficult once a person becomes obese.[ 14 , 30 ] Evaluating the long term effect of weight change, particularly weight gain from early to middle adulthood, on future health is thus important. Weight gain from early to middle adulthood is a well-established risk factor for diabetes, hypertension, cardiovascular disease, cancer, non-traumatic death, and many other diseases.[ 14 – 17 ] Our findings support adding asthma to this list and should provide yet one more piece of information to prevent weight gain and to support the aggressive implementation of public health measures to support the attainment of this goal. We used population attributable fraction to explore the potential effect of prevention initiatives targeting weight gain. If all those who were non-obesity at age 25 prevent weight gain by midlife, 10.2% of observed incident cases of adult-onset asthma could be averted. In total, we found that 21.8% of asthma new cases during this time period could be reduced if the entire population maintained a weight in the normal range between early and middle adulthood in U.S. adults. Our study had several strengths. Using a retrospective cohort design, we were able to take advantage of a large, nationally representative cohort of U.S. adults to estimate associations between weight change and incident asthma across the life course. As a nationally representative survey, results using NHANES are more broadly generalizable than those from other cohorts like the NHS, CTS and E3N Cohort Study. The advantage of focusing on weight gain throughout adult life is that it primarily reflects the accumulation of excess adiposity from early to middle adulthood, which is often ignored by individuals and their physicians because the consequences of modest weight accumulation may not yet be apparent. If the association between early adulthood weight gain and adult-onset asthma is proved to be causal, understanding and preventing early adulthood weight gain would be the next steps in research and translation, which is not only beneficial to future cardio-metabolic health, but also to mitigation of future asthma risk. Our study also had several limitations. Firstly, we used recalled and self-reported weight data at age 25 years and 10 years before the NHANES survey and thus misclassification bias might have been introduced. However, a recent meta-analysis showed that recalled early life weight could be a valid measure to use in life course epidemiological analysis.[ 31 ] Secondly, we could not adjust for physical activity or diet because recall data on these variables were not collected. The results might thus partly reflect the effects of physical activity and dietary factors over the life course. Thirdly, members of the relevant cohorts who had died before the survey were not represented in the retrospective data set. Their experience might have differed from that of survivors in ways that affected the estimated relationship between obesity and asthma. Furthermore, our report relied on self-reported data on asthma status, which may have missed people who had not been diagnosed with the condition. Lastly, we did not evaluate the relations of changes in other adiposity related markers such as waist circumference and fat mass with incident asthma owing to lack of data at different time points. Further studies with repeated data on these markers may provide a more comprehensive picture of the changes in obesity status and asthma risk. Conclusions Our study found that weight gain from young to middle adulthood was associated with increased risks of incident asthma in women but not men. Future studies are needed to unravel the mechanisms underlying the association between weight change across adulthood and adult -onset asthma, particularly the relations of changes in body composition to asthma. In addition, as weight loss was less achievable (only 0.9% participants changed from the obesity to the non-obesity category from early to middle adulthood), our results suggested that prevention of weight gain might be more important. If all those who were non-obesity at early adulthood prevented weight gain by midlife, approximately 10% of adult-onset asthma could be averted. Taken together, the findings indicated that maintaining normal weight throughout the adulthood, especially prevention of weight gain in early adulthood, should be encouraged to reduce risk of adult-onset asthma. Therefore, monitoring weight change since young adulthood could provide a sensitive and useful clinical measure for early detection of adverse trends in asthma risk. Abbreviations NHANES, National Health and Nutrition Examination Survey; NCHS, National Center for Health Statistics; CDC, Centers for Disease Control and Prevention; BMI, body mass index; PAF, population attributable fractions; CTS, California Teachers Study; NHS, Nurses’ Health Study; E3N, Etude Epidémiologique auprès de femmes de l’Education Nationale. Declarations Acknowledgements Not applicable. Author contributions TW, YPZ, and YXZ conceived of and designed the study; TW, YPZ, NK, and JZZ performed the data collection, management and analyses; TW and YPZ interpreted the results and drafted the manuscript; and GC and YXZ critically edited the manuscript. All authors read and approved the final manuscript. Funding This work was supported by the National Key R&D Program of China of Ministry of Science and Technology of the People's Republic of China [2017YFC1600200]; National Natural Science Foundation of China [91643203]; and Postdoctoral Science Foundation of China [2019M660161]. The study funders had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; or decision to submit the manuscript for publication. Availability of data and materials The datasets generated and analysed during the current study are available at NHANES official website (https://wwwn.cdc.gov/nchs/nhanes/Default.aspx). Ethics approval and consent to participate Not applicable. Consent for publication Not applicable. Competing interests The authors declare that they have no competing interests. References Hales CM, Carroll MD, Fryar CD, Ogden CL. Prevalence of Obesity and Severe Obesity Among Adults: United States, 2017–2018 . NCHS data brief 2020:1–8. Akinbami LJ, Fryar CD. Current Asthma Prevalence by Weight Status Among Adults: United States, 2001–2014 . NCHS data brief 2016:1–8. Beuther DA, Sutherland ER. 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Associations of Weight Gain From Early to Middle Adulthood With Major Health Outcomes Later in Life. JAMA. 2017;318:255–69. Jia G, Shu X-O, Liu Y, Li H-L, Cai H, Gao J, Gao Y-T, Wen W, Xiang Y-B, Zheng W. Association of Adult Weight Gain With Major Health Outcomes Among Middle-aged Chinese Persons With Low Body Weight in Early Adulthood. JAMA network open. 2019;2:e1917371. Zipf G, Chiappa M, Porter KS, Ostchega Y, Lewis BG, Dostal J. National health and nutrition examination survey: plan and operations, 1999–2010. Vital and health statistics Ser 1, Programs and collection procedures 2013. Berry KM, Neogi T, Baker JF, Collins JM, Waggoner JR, Hsiao C-W, Johnston SS, LaValley MP, Stokes A: Obesity Progression between Young Adulthood and Midlife and Incident Arthritis : A Retrospective Cohort Study of US Adults . Arthritis care & research 2020. Zhou Y, Wang T, Yin X, Sun Y, Seow WJ. Association of Weight Loss from Early to Middle Adulthood and Incident Hypertension Risk Later in Life . Nutrients 2020, 12. Bundy JD, Mills KT, Chen J, Li C, Greenland P, He J. Estimating the Association of the 2017 and 2014 Hypertension Guidelines With Cardiovascular Events and Deaths in US Adults: An Analysis of National Data. JAMA cardiology. 2018;3:572–81. Von Behren J, Lipsett M, Horn-Ross PL, Delfino RJ, Gilliland F, McConnell R, Bernstein L, Clarke CA, Reynolds P. Obesity, waist size and prevalence of current asthma in the California Teachers Study cohort. Thorax. 2009;64:889–93. Camargo CA, Weiss ST, Zhang S, Willett WC, Speizer FE. Prospective study of body mass index, weight change, and risk of adult-onset asthma in women. Arch Intern Med. 1999;159:2582–8. Beckett WS, Jacobs DR, Yu X, Iribarren C, Williams OD. Asthma is associated with weight gain in females but not males, independent of physical activity. Am J Respir Crit Care Med. 2001;164:2045–50. Romieu I, Avenel V, Leynaert B, Kauffmann F, Clavel-Chapelon F. Body mass index, change in body silhouette, and risk of asthma in the E3N cohort study. Am J Epidemiol. 2003;158:165–74. Hasler G, Gergen PJ, Ajdacic V, Gamma A, Eich D, Rössler W, Angst J. Asthma and body weight change: a 20-year prospective community study of young adults. Int J Obes. 2006;30:1111–8. Scott HA, Gibson PG, Garg ML, Wood LG. Airway inflammation is augmented by obesity and fatty acids in asthma. Eur Respir J. 2011;38:594–602. Han Y-Y, Forno E, Celedón JC. Sex Steroid Hormones and Asthma in a Nationwide Study of U.S. Adults. Am J Respir Crit Care Med. 2020;201:158–66. Carey MA, Card JW, Voltz JW, Arbes SJ, Germolec DR, Korach KS, Zeldin DC. It's all about sex: gender, lung development and lung disease. Trends Endocrinol Metab. 2007;18:308–13. Fontana L, Hu FB. Optimal body weight for health and longevity: bridging basic, clinical, and population research. Aging cell. 2014;13:391–400. De Rubeis V, Bayat S, Griffith LE, Smith BT, Anderson LN. Validity of self-reported recall of anthropometric measures in early life: A systematic review and meta-analysis. Obesity reviews: an official journal of the International Association for the Study of Obesity. 2019;20:1426–40. Supplementary Files WeightchangeSupplementary1209.doc WeightchangeSupplementary1209.doc Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Major revision 06 Feb, 2021 Review # 2 received at journal 23 Jan, 2021 Reviewer # 2 agreed at journal 09 Jan, 2021 Review # 1 received at journal 27 Dec, 2020 Reviewer # 1 agreed at journal 11 Dec, 2020 Reviewers invited by journal 09 Dec, 2020 First submitted to journal 08 Dec, 2020 Editor assigned by journal 08 Dec, 2020 Submission checks completed at journal 08 Dec, 2020 Editor invited by journal 08 Dec, 2020 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. 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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-127866","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research","associatedPublications":[],"authors":[{"id":6371743,"identity":"7b4aeccb-5beb-4743-9e0d-da912ce719a3","order_by":0,"name":"Tao Wang","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA+ElEQVRIiWNgGAWjYBACfmbGxgcJBhI89u3NBxh4QEIHCGiRbG9uNvhQYCNnwHMsgTgtBmeOt0nO+JBmbCDhY0CcFoYbic3GPAaHE7dL8Hy88baNQY7vRgLj5wI8OhhnJDY+BmnZObt3s+XcNgZjyRsJzNIz8GhhloDa0nDn7DZp3jaGxA03EtiYefBoYZNIbJMGa7mR8wykpZ6gFh6eg0DvGwC9fyOHDaQlwYCQFgn2RmAgG9jISfYcM7acc07CcOaZh83S+LTYH2Z/+CDhjwQPP3vzwxtvymzk+Y4nH/yMTwuqlWDEwNhArAaI+lEwCkbBKBgFGAAA87xR9c4396MAAAAASUVORK5CYII=","orcid":"https://orcid.org/0000-0002-5910-8775","institution":"Qingdao University","correspondingAuthor":true,"prefix":"","firstName":"Tao","middleName":"","lastName":"Wang","suffix":""},{"id":6371744,"identity":"c2eda5cb-41b6-4fdb-b45f-e088287104ab","order_by":1,"name":"Yunping Zhou","email":"","orcid":"","institution":"Qingdao University","correspondingAuthor":false,"prefix":"","firstName":"Yunping","middleName":"","lastName":"Zhou","suffix":""},{"id":6371745,"identity":"8d2be283-ba6e-4a02-ada8-51803c6415ad","order_by":2,"name":"Nan Kong","email":"","orcid":"","institution":"Qingdao University","correspondingAuthor":false,"prefix":"","firstName":"Nan","middleName":"","lastName":"Kong","suffix":""},{"id":6371746,"identity":"8c29f786-9a22-4e04-86e5-982f71729262","order_by":3,"name":"Jianzhong Zhang","email":"","orcid":"","institution":"Qingdao University","correspondingAuthor":false,"prefix":"","firstName":"Jianzhong","middleName":"","lastName":"Zhang","suffix":""},{"id":6371747,"identity":"29d3fa79-2915-4633-a31d-f7b01920d971","order_by":4,"name":"Guo Cheng","email":"","orcid":"","institution":"Sichuan University","correspondingAuthor":false,"prefix":"","firstName":"Guo","middleName":"","lastName":"Cheng","suffix":""},{"id":6371748,"identity":"bbf42d3d-ba92-4de6-b06a-3d34095c954e","order_by":5,"name":"Yuxin Zheng","email":"","orcid":"","institution":"Qingdao University","correspondingAuthor":false,"prefix":"","firstName":"Yuxin","middleName":"","lastName":"Zheng","suffix":""}],"badges":[],"createdAt":"2020-12-13 19:18:22","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-127866/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-127866/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":4291020,"identity":"abf3ec95-7aa9-4845-8422-e4208478d8d2","added_by":"auto","created_at":"2020-12-15 23:55:42","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":210621,"visible":true,"origin":"","legend":"Cumulative incidence curve for asthma. Multivariable Cox regression model adjusted for baseline age, sex, race/ethnicity, education level, family income-poverty ratio level, smoking status, and family history of asthma. (A) Stable Non-obesity, Non-obesity to Obesity, Obesity to Non-obesity, Stable Obesity. (B) Absolute weight change.","description":"","filename":"OnlineFIG1.Png","url":"https://assets-eu.researchsquare.com/files/rs-127866/v1/4a9ce34a238d5b4d119f8fef.Png"},{"id":4291015,"identity":"96cbb5ea-d749-4e59-bd6f-4b5a917cb355","added_by":"auto","created_at":"2020-12-15 23:55:12","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":210621,"visible":true,"origin":"","legend":"Cumulative incidence curve for asthma. Multivariable Cox regression model adjusted for baseline age, sex, race/ethnicity, education level, family income-poverty ratio level, smoking status, and family history of asthma. (A) Stable Non-obesity, Non-obesity to Obesity, Obesity to Non-obesity, Stable Obesity. (B) Absolute weight change.","description":"","filename":"OnlineFIG1.Png","url":"https://assets-eu.researchsquare.com/files/rs-127866/v1/1026a6c6cacf94053be3807e.Png"},{"id":4291021,"identity":"82b91d9d-95f1-4a51-8166-89adecfebc9e","added_by":"auto","created_at":"2020-12-15 23:55:43","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":396435,"visible":true,"origin":"","legend":"Associations between weight change patterns across adulthood and risk of incident asthma stratified by baseline age, sex, smoking status, and family history of asthma in NHANES 1999-2016. All estimates accounted for complex survey design of NHANES. Risk estimates were adjusted for baseline age (not adjusted in subgroup analysis by age), sex (not adjusted in subgroup analysis by sex), race/ethnicity, education level, family income-poverty ratio level, smoking status (not adjusted in subgroup analysis by smoking status), and family history of asthma. All P values for interaction were \u003e0.05. ","description":"","filename":"OnlineFIG2.Png","url":"https://assets-eu.researchsquare.com/files/rs-127866/v1/bce0ae7c4fd95586cbca5e1d.Png"},{"id":4291016,"identity":"0f3206ca-1ddb-4876-aa31-cc649664ffdf","added_by":"auto","created_at":"2020-12-15 23:55:12","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":396435,"visible":true,"origin":"","legend":"Associations between weight change patterns across adulthood and risk of incident asthma stratified by baseline age, sex, smoking status, and family history of asthma in NHANES 1999-2016. All estimates accounted for complex survey design of NHANES. Risk estimates were adjusted for baseline age (not adjusted in subgroup analysis by age), sex (not adjusted in subgroup analysis by sex), race/ethnicity, education level, family income-poverty ratio level, smoking status (not adjusted in subgroup analysis by smoking status), and family history of asthma. All P values for interaction were \u003e0.05. ","description":"","filename":"OnlineFIG2.Png","url":"https://assets-eu.researchsquare.com/files/rs-127866/v1/e9c83dcacd1405979ca3fe83.Png"},{"id":13634042,"identity":"a2489ba7-6e01-4c39-85f1-1b4b5377533a","added_by":"auto","created_at":"2021-09-17 08:30:21","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1232591,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-127866/v1/4f80f9bb-0cda-4245-b9d9-7b0918df1b80.pdf"},{"id":4291022,"identity":"d9e9189d-afe8-4fe9-94ed-874068f6c269","added_by":"auto","created_at":"2020-12-15 23:55:43","extension":"doc","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":72192,"visible":true,"origin":"","legend":"","description":"","filename":"WeightchangeSupplementary1209.doc","url":"https://assets-eu.researchsquare.com/files/rs-127866/v1/d453ebdf4d39c8e82f926ecf.doc"},{"id":4291017,"identity":"b01ca69d-ba2a-4aef-929d-60e192ee2b84","added_by":"auto","created_at":"2020-12-15 23:55:13","extension":"doc","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":72192,"visible":true,"origin":"","legend":"","description":"","filename":"WeightchangeSupplementary1209.doc","url":"https://assets-eu.researchsquare.com/files/rs-127866/v1/ee5101e71105faff04b72b40.doc"}],"financialInterests":"","formattedTitle":"\u003cp\u003eWeight Change from Early to Middle Adulthood and Incident Asthma Later in Life: A Retrospective Cohort Study\u003c/p\u003e","fulltext":[{"header":"Introduction","content":" \u003cp\u003eAsthma and obesity are major public health problems that have increased in the past decades. From 1999 through 2018, the age-adjusted prevalence of obesity among adults increased from 30.5\u0026ndash;42.4% in the United States.[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e] Although asthma was less prevalent than obesity, it also increased from 7.1\u0026ndash;9.2% between 2001 and 2014.[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e] The increasing prevalence of asthma and obesity suggested an association between the two conditions. A meta-analysis of seven prospective studies involving more than 300 000 adults found a dose-response relationship between obesity and asthma: the odds ratio of incident asthma was 1.5 in the overweight and 1.9 in the obesity groups compared with the lean group.[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e] Results from Mendelian Randomization studies provided causal evidence for obesity increasing the risk of asthma.[\u003cspan additionalcitationids=\"CR5\" citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eHowever, many previous cohort studies[\u003cspan additionalcitationids=\"CR8 CR9\" citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e] included only a single measurement of BMI, which ignored the dynamic feature of body weight over time. Thus more studies are needed to assess the long term consequences of weight change during certain life periods. A meta-analysis including 147 252 European children in 31 birth cohort studies found that rapid weight gain in infancy was positively associated with childhood asthma.[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e] The Taiwan Children Health Study in school-age children reported that rapid adiposity growth might increase risks of childhood asthma.[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e] In contrast to childhood-onset asthma, less is known about the factors associated with adult-onset asthma, particularly from longitudinal studies.[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e] Asthma that starts in adulthood differs from childhood-onset asthma in that it is often non-atopic, more severe and associated with a faster decline in lung function.[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eExcess adiposity tends to accrue during early and middle adulthood for most people. Adult weight gain has been associated with increased mortality risk, diabetes, hypertension, cardiovascular disease, several types of cancer, etc.[\u003cspan additionalcitationids=\"CR15 CR16\" citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e] However, studies exploring the effect of weight change from early to middle adulthood on adult-onset asthma were limited. Therefore, this study aimed to examine the relations of weight changes from early (age 25\u0026nbsp;years) to middle adulthood (mean age 44\u0026nbsp;years) with asthma incidence in the United States.\u003c/p\u003e "},{"header":"Methods","content":" \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy Design and Population\u003c/h2\u003e \u003cp\u003eDetails of National Health and Nutrition Examination Survey (NHANES) have been described elsewhere.[\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e] NHANES is a series of ongoing cross-sectional surveys conducted by the National Center for Health Statistics (NCHS) of the Centers for Disease Control and Prevention (CDC). Representative samples of the non-institutional U.S. population were selected by a complex stratified, multistage probability sampling design. NHANES was approved by the National Center for Health Statistics research ethics review board, and written informed consent from all the participants was provided during the survey. Because the data are publicly available and de-identified, institutional review board approval was not required for this analysis.\u003c/p\u003e \u003cp\u003eThis study used data across 9 cycles of the continuous NHANES (1999\u0026ndash;2000 through 2015\u0026ndash;2016) including adults aged 40\u0026ndash;74\u003csup\u003e[15]\u003c/sup\u003e at examination. We used recall questions on weight history and age at asthma diagnosis to create a retrospective cohort from the cross-sectional data. Specifically, self-reported weight change was assessed by participant recall of weight at age 25 and 10\u0026nbsp;years before the NHANES survey. We defined baseline as 10\u0026nbsp;years before the survey. Incident asthma was determined from respondents affirming that a health care provider had indicated a diagnosis of asthma. The reported age at diagnosis was used to establish the time of asthma onset. The design method for retrospective cohort study has been described in detail in a previous publication using NHANES data.[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e] The study design was visually depicted in Figure S1.\u003c/p\u003e \u003cp\u003eParticipants who reported a date of onset that was before the initiation of follow-up were considered prevalent asthma cases and were excluded. We also excluded participants missing information of asthma diagnosis, those without diagnosis time and those without BMI at age 25\u0026nbsp;years and (or) at age 10\u0026nbsp;years before survey. Finally, a sample size of 20 771 individuals remained in our cohort for analysis (Figure S2).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003eAssessments of weight change\u003c/h2\u003e \u003cp\u003eData on weight at age 25\u0026nbsp;years and at 10\u0026nbsp;years before the NHANES survey were recalled. Measured height at the examination was used to calculate BMI, unless the participant was 50\u0026nbsp;years or older at the time of the survey. In this case, reported height at 25 was used to calculate BMI at 25, and measured height at the examination was used to calculate BMI at 10\u0026nbsp;years before the survey.\u003csup\u003e[15]\u003c/sup\u003e We categorized each of the two BMI variables into three groups: underweight and normal weight (\u0026lt;\u0026thinsp;25.0), overweight (25.0-29.9), and obesity (\u0026ge;\u0026thinsp;30.0).\u003c/p\u003e \u003cp\u003eBMI change categories were then generated to capture weight change over the life course of an individual. We defined four weight change patterns based on BMI (kg/m\u003csup\u003e2\u003c/sup\u003e) at age 25 and on BMI 10\u0026nbsp;years prior to the survey: stable non-obesity pattern (BMI\u003csub\u003eage 25\u003c/sub\u003e \u0026lt;30\u0026nbsp;kg/m\u003csup\u003e2\u003c/sup\u003e and BMI\u003csub\u003e10 years prior\u003c/sub\u003e \u0026lt;30) (reference group), non-obesity to obesity pattern (BMI\u003csub\u003eage 25\u003c/sub\u003e \u0026lt;30\u0026nbsp;kg/m\u003csup\u003e2\u003c/sup\u003e and BMI\u003csub\u003e10 years prior\u003c/sub\u003e \u0026ge;30), obesity to non-obesity pattern (BMI\u003csub\u003eage 25\u003c/sub\u003e \u0026ge;30\u0026nbsp;kg/m\u003csup\u003e2\u003c/sup\u003e and BMI\u003csub\u003e10 years prior\u003c/sub\u003e \u0026lt;30), stable obesity pattern (BMI\u003csub\u003eage 25\u003c/sub\u003e \u0026ge;30\u0026nbsp;kg/m\u003csup\u003e2\u003c/sup\u003e and BMI\u003csub\u003e10 years prior\u003c/sub\u003e \u0026ge;30). We also classified absolute weight change in each time interval into five groups: weight loss of at least 2.5\u0026nbsp;kg, weight change within 2.5\u0026nbsp;kg (reference group), weight gain of at least 2.5\u0026nbsp;kg but less than 10.0\u0026nbsp;kg, weight gain of at least 10\u0026nbsp;kg but less than 20.0\u0026nbsp;kg, and weight gain of at least 20.0\u0026nbsp;kg. These weight change categories were comparable with those used in previous studies.[\u003cspan additionalcitationids=\"CR15\" citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eCovariates\u003c/h2\u003e \u003cp\u003eInformation on covariates was available through questionnaires, including age, sex, race/ethnicity (Mexican American, non-Hispanic white, non-Hispanic black, other), education level (less than high school, high school or equivalent, and college or above), family income-poverty ratio (\u0026le;\u0026thinsp;1.3, ~\u0026thinsp;1.85, ~\u0026thinsp;3.0, and \u0026gt;\u0026thinsp;3.0), smoking status (ever and never smokers), and family history of asthma.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eAll analyses incorporated the sample weights, stratification, and clustering of the complex sampling design to ensure nationally representative estimates. Descriptive characteristics were computed through means and 95% confidence intervals for continuous variables and percentages for categorical and binary variables. We used Cox proportional hazards models with time in study as the underlying time metric to estimate the hazard ratio and corresponding 95% confidence intervals for incident asthma in relation to weight change patterns from age 25\u0026nbsp;years to 10\u0026nbsp;years before survey.\u003c/p\u003e \u003cp\u003eFor the main analyses, we examined the associations between the four weight change patterns and developing asthma. The stable non-obesity pattern was used as the reference to which all other weight change patterns were compared. We adjusted for baseline age, sex, and race/ethnicity in model 1. We further adjusted for education level, family income-poverty ratio level, smoking status, and family history of asthma in model 2. Dummy variables were used to indicate missing data for the covariates. Subgroup analyses and potential effect modifications were conducted by baseline age (\u0026lt;\u0026thinsp;50 and \u0026ge;\u0026thinsp;50\u0026nbsp;years), sex, smoking status, and family history of asthma.\u003c/p\u003e \u003cp\u003eA secondary analysis was implemented in which those who maintained a normal BMI during the time period were treated as a separate category of BMI change. In doing so, those originally in the stable non-obesity pattern were categorized into two new groups: 1) stable normal pattern (BMI\u003csub\u003eage 25\u003c/sub\u003e \u0026lt;25.0\u0026nbsp;kg/m\u003csup\u003e2\u003c/sup\u003e and BMI\u003csub\u003e10 years prior\u003c/sub\u003e \u0026lt;25.0), and 2) maximum overweight pattern (25.0-29.9\u0026nbsp;at either time but not \u0026ge;\u0026thinsp;30.0\u0026nbsp;at the other time). Stable normal pattern was used as the reference category for this model.\u003c/p\u003e \u003cp\u003eWe also investigated the associations between absolute weight change groups and incident asthma risk, as well as the linear dose-response relation. For test of trend, we calculated the association with incident asthma by treating the categories of absolute weight change as ordinal variables.\u003c/p\u003e \u003cp\u003eFinally, we calculated population attributable fractions (PAFs) of incident asthma owing to weight change using the following formula:[\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]\u003cdiv id=\"Equa\" class=\"Equation\"\u003e\u003c/div\u003e\u003c/p\u003e \n\u003cp\u003e\u003cimg src=\"data:image/png;base64,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\"\u003e\u003c/p\u003e\n\u003cp\u003ewhere \u003cem\u003ep\u003c/em\u003e\u003csub\u003e\u003cem\u003ei\u003c/em\u003e\u003c/sub\u003e is the proportion of weight change pattern \u003cem\u003ei\u003c/em\u003e, \u003cem\u003eHR\u003c/em\u003e\u003csub\u003e\u003cem\u003ei\u003c/em\u003e\u003c/sub\u003e is the hazard ratio of incident asthma in weight change pattern \u003cem\u003ei\u003c/em\u003e, and \u003cem\u003ek\u003c/em\u003e is the total number of weight change patterns. A given PAF represents the proportion of incident asthmas that could be reduced if people with a particular weight change pattern were redistributed to another pattern and experienced the same relative risks as individuals in that new pattern.\u003c/p\u003e \u003cp\u003eAll statistical analyses were conducted in 2020 using SAS 9.4 (site 70239492) and R version 3.6.3. All \u003cem\u003eP\u003c/em\u003e values were 2-tailed (\u003cem\u003eα\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.05).\u003c/p\u003e \u003c/div\u003e "},{"header":"Results","content":" \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eBaseline characteristics and weight change pattern\u003c/h2\u003e \u003cp\u003eTable\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e reported characteristics of the sample with weighted estimates and unweighted sample sizes stratified by weight change category. The mean age of the sample was 44.2\u0026nbsp;years at baseline, and 50.7% were female. The study sample was 73.4% non-Hispanic white, 10.3% non-Hispanic black, 6.0% Mexican American, and 10.3% others. The mean BMI was 23.5\u0026nbsp;kg/m\u003csup\u003e2\u003c/sup\u003e at age 25, and 27.1\u0026nbsp;kg/m\u003csup\u003e2\u003c/sup\u003e at baseline. On average, participants gained 9.4\u0026nbsp;kg weight from age 25\u0026nbsp;years to baseline.\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\u003eCharacteristics of study participants in NHANES 1999\u0026ndash;2016 according to weight change patterns from age 25\u0026nbsp;years to ten years before survey. \u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCharacteristics\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eStable Non-obesity\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eNon-obesity to Obesity\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eObesity to Non-obesity\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eStable Obesity\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eTotal\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eParticipants\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e15293 (75.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4015 (18.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e209 (0.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1254 (5.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e20771\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eMean (95% CI) baseline age, years\u003c/b\u003e \u003csup\u003e\u003cb\u003eb\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e43.9 (43.6, 44.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e46.9 (46.4, 47.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e41.0 (39.7, 42.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e41.4 (40.7, 42.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e44.2 (44.0, 44.5)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eFemale\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e7621 (52.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1965 (47.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e83 (40.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e598 (44.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e10267 (50.7)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eRace/ethnicity\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMexican American\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2542 (5.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e824 (7.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e54 (8.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e229 (7.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e3649 (6.0)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNon-Hispanic White\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e6854 (73.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1773 (74.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e87 (70.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e510 (70.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e9224 (73.4)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNon-Hispanic Black\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e3177 (9.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e970 (11.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e43 (11.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e393 (15.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e4583 (10.3)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOther\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2720 (11.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e448 (7.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e25 (9.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e122 (6.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e3315 (10.3)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eEducation\u003c/b\u003e \u003csup\u003e\u003cb\u003ec\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLess than high school\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e4029 (16.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1160 (17.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e82 (22.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e348 (16.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e5619 (16.3)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHigh school or equivalent\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e3526 (23.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e983 (26.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e41 (19.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e320 (27.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e4870 (24.0)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCollege or above\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e7730 (60.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1870 (56.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e86 (57.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e585 (57.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e10271 (59.7)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eFamily income-poverty ratio level\u003c/b\u003e \u003csup\u003e\u003cb\u003ec\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e0\u0026thinsp;~\u0026thinsp;1.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e3521 (15.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1017 (17.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e75 (28.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e359 (19.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e4972 (15.8)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e~\u0026thinsp;1.85\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1618 (8.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e453 (9.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e26 (10.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e146 (10.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e2243 (8.4)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e~\u0026thinsp;3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2448 (16.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e727 (19.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e32 (14.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e219 (17.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e3426 (16.8)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e6362 (60.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1496 (54.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e67 (46.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e430 (51.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e8355 (59.0)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eEver Smoker\u003c/b\u003e \u003csup\u003e\u003cb\u003eb\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e7286 (48.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1880 (48.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e133 (62.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e545 (43.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e9844 (48.4)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eFamily history of asthma\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1668 (15.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e534 (17.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e27 (18.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e198 (21.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e2427 (16.4)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eMean (95% CI) body mass index\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAt age 25\u0026nbsp;years\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e22.1 (22.0, 22.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e25.0 (24.8, 25.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e34.0 (33.2, 34.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e34.7 (34.4, 35.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e23.5 (23.4, 23.6)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAt 10\u0026nbsp;years before survey\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e24.6 (24.5, 24.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e34.0 (33.8, 34.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e27.0 (26.5, 27.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e38.8 (38.3, 39.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e27.1 (27.0, 27.3)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eMean (95% CI) absolute weight change, kg\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e6.2 (6.1, 6.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e23.5 (22.9, 24.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e-19.1 (-22.2, -16.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e10.5 (9.1, 11.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e9.4 (9.1, 9.6)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"6\"\u003e\u003csup\u003ea\u003c/sup\u003e All estimates accounted for complex survey designs. \u003csup\u003eb\u003c/sup\u003e At start of follow-up. \u003csup\u003ec\u003c/sup\u003e At end of follow-up\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eRegarding life-course weight change, 75.2% of the participants were in the stable non-obesity group, 5.9% were in the stable obesity group, 18.0% of the participants moved from non-obesity to obesity and they gained 23.5\u0026nbsp;kg on average, whereas only 0.9% of the participants moved from the obesity to non-obesity category and they lost 19.1\u0026nbsp;kg on average.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003eRelations of weight change patterns with incident asthma\u003c/h2\u003e \u003cp\u003eAmong 20 771 participants, 627 had a diagnosis of asthma, yielding an overall incidence rate of 3.1 per 1000 person-years. Figure\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e presented cumulative incidence curves by time in study for each weight change group. Compared with stable non-obesity individuals, stable obesity participants had increased risks of incident asthma during the 10\u0026nbsp;years of follow-up, with hazard ratio of 1.41 (95% confidence interval 0.97 to 2.05) (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Moving from the non-obesity range at age 25\u0026nbsp;years to the obesity range at baseline was associated with a 63% higher risk of incident asthma (hazard ratio 1.63, 1.29 to 2.07). No significant difference (hazard ratio 1.21, 0.41 to 3.62) was observed in the risk of onset asthma between those changing from obesity to non-obesity and those who maintained stable non-obesity from young adulthood through midlife. The population attributable fractions were calculated to estimate the percentage of asthmas that could be averted under hypothetical scenarios. If those who gained weight from the non-obesity range at age 25\u0026nbsp;years to the obesity range at baseline had not gained weight, 10.2% of the adult-onset asthmas would have been averted in U.S. adults. Furthermore, 12.7% of the adult-onset asthmas would have been averted, if the total population had a stable non-obesity pattern from young adulthood through midlife.\u003c/p\u003e \u003cp\u003e \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\u003eHazard ratios (95% CIs) of incident asthma with weight change patterns across adulthood in NHANES 1999\u0026ndash;2016. \u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eWeight Change Patterns\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eNo of incident asthma /person-years\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e \u003cp\u003eModel 1 \u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e \u003cp\u003eModel 2 \u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eHR (95% CI)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eHR (95% CI)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCategory 1 \u003csup\u003ed\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eStable Non-obesity\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e402/151360\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNon-obesity to Obesity\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e165/39485\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.66 (1.30, 2.11)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.63 (1.29, 2.07)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eObesity to Non-obesity\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7/2067\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.47 (0.50, 4.27)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.479\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.21 (0.41, 3.62)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.730\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eStable Obesity\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e53/12305\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.48 (1.02, 2.16)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.041\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.41 (0.97, 2.05)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.075\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCategory 2 \u003csup\u003ee\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWeight loss\u0026thinsp;\u0026ge;\u0026thinsp;2.5\u0026nbsp;kg\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e33/11163\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.01 (0.60, 1.72)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.964\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.91 (0.53, 1.56)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.725\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWeight change within 2.5\u0026nbsp;kg\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e126/48635\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWeight gain\u0026thinsp;\u0026ge;\u0026thinsp;2.5\u0026nbsp;kg and \u0026lt;\u0026thinsp;10\u0026nbsp;kg\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e180/66293\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.95 (0.70, 1.30)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.744\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.99 (0.73, 1.34)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.938\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWeight gain\u0026thinsp;\u0026ge;\u0026thinsp;10\u0026nbsp;kg and \u0026lt;\u0026thinsp;20\u0026nbsp;kg\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e139/46712\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.15 (0.85, 1.56)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.372\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.19 (0.88, 1.60)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.253\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWeight gain\u0026thinsp;\u0026ge;\u0026thinsp;20\u0026nbsp;kg\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e149/32414\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.52 (1.14, 2.03)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.005\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.53 (1.15, 2.03)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.004\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"6\"\u003e\u003csup\u003ea\u003c/sup\u003e All estimates accounted for complex survey designs.\u003c/td\u003e\u003c/tr\u003e \u003ctr\u003e\u003ctd colspan=\"6\"\u003e\u003csup\u003eb\u003c/sup\u003e Model 1 was adjusted for baseline age, sex, race/ethnicity.\u003c/td\u003e\u003c/tr\u003e \u003ctr\u003e\u003ctd colspan=\"6\"\u003e\u003csup\u003ec\u003c/sup\u003e Model 2 was additionally adjusted for education level, family income-poverty ratio level, smoking status, and family history of asthma. In the Category 2 analyses, we also included BMI at the age 25\u0026nbsp;years as potential confounders in model 2.\u003c/td\u003e\u003c/tr\u003e \u003ctr\u003e\u003ctd colspan=\"6\"\u003e\u003csup\u003ed\u003c/sup\u003e Stable Non-obesity, BMI\u003csub\u003eage 25\u003c/sub\u003e \u0026lt;30\u0026nbsp;kg/m\u003csup\u003e2\u003c/sup\u003e and BMI\u003csub\u003e10 years prior\u003c/sub\u003e \u0026lt;30; Non-obesity to Obesity, BMI\u003csub\u003eage 25\u003c/sub\u003e \u0026lt;30\u0026nbsp;kg/m\u003csup\u003e2\u003c/sup\u003e and BMI\u003csub\u003e10 years prior\u003c/sub\u003e \u0026ge;30; Obesity to Non-obesity, BMI\u003csub\u003eage 25\u003c/sub\u003e \u0026ge;30\u0026nbsp;kg/m\u003csup\u003e2\u003c/sup\u003e and BMI\u003csub\u003e10 years prior\u003c/sub\u003e \u0026lt;30; Stable Obesity, BMI\u003csub\u003eage 25\u003c/sub\u003e \u0026ge;30\u0026nbsp;kg/m\u003csup\u003e2\u003c/sup\u003e and BMI\u003csub\u003e10 years prior\u003c/sub\u003e \u0026ge;30.\u003c/td\u003e\u003c/tr\u003e \u003ctr\u003e\u003ctd colspan=\"6\"\u003e\u003csup\u003ee\u003c/sup\u003e Absolute weight change: weight loss of at least 2.5\u0026nbsp;kg, weight change within 2.5\u0026nbsp;kg, weight gain of at least 2.5\u0026nbsp;kg but less than 10.0\u0026nbsp;kg, weight gain of at least 10\u0026nbsp;kg but less than 20.0\u0026nbsp;kg, and weight gain of at least 20.0\u0026nbsp;kg.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eIn the stratified analyses, the associations were stronger among participants who were more than 50\u0026nbsp;years old at baseline, female, never smoking, no family history of asthma compared with their counterparts (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). However, we found no significant interactions with baseline age, sex, smoking status and family history of asthma.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eIn the secondary analysis (Table S1), compared with the stable normal group, the maximum overweight group was not significantly associated with incident asthma risk (hazard ratio 1.19, 0.94 to 1.50); stable obesity had a hazard ratio of 1.52 (1.03 to 2.25) for incident asthma during the period; non-obesity to obesity pattern was consistently associated with highest incident asthma risk (hazard ratio 1.77, 1.35 to 2.32). Population attributable fraction calculation estimated that 21.8% of the adult-onset asthmas would have been averted, if the total population had a stable normal pattern from young adulthood through midlife.\u003c/p\u003e \u003cp\u003eWhen evaluating the absolute weight changes, the hazard ratios for incident asthma in the extreme weight gain (weight gain\u0026thinsp;\u0026ge;\u0026thinsp;20\u0026nbsp;kg) group were 1.53 (1.15 to 2.03) from age 25\u0026nbsp;years to baseline, compared with the stable weight group (weight change within 2.5\u0026nbsp;kg) (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Moderate to large weight gain (weight gain\u0026thinsp;\u0026ge;\u0026thinsp;10\u0026nbsp;kg and \u0026lt;\u0026thinsp;20\u0026nbsp;kg), small to moderate weight gain (weight gain\u0026thinsp;\u0026ge;\u0026thinsp;2.5\u0026nbsp;kg and \u0026lt;\u0026thinsp;10\u0026nbsp;kg) and weight loss (more than 2.5\u0026nbsp;kg) were not significantly associated with incident asthma. Furthermore, we identified a linear dose-response association between absolute weight change across adulthood and risk of incident asthma (\u003cem\u003eP\u003c/em\u003e for trend\u0026thinsp;=\u0026thinsp;0.024). These associations were independent of BMI at age 25\u0026nbsp;years. When we restricted the analysis to participants who had a BMI of \u0026lt;\u0026thinsp;25\u0026nbsp;at 25\u0026nbsp;years of age, results remained similar, suggesting that our estimates were not driven by participants with high BMIs who gained additional weight (data not shown).\u003c/p\u003e \u003c/div\u003e "},{"header":"Discussion","content":" \u003cp\u003eIn this large retrospective cohort study of nationally representative U.S. adults, the highest risk of incident asthma was in participants who were weight gain (non-obesity to obesity) from early to middle adulthood; stable obesity across adulthood was also associated with increased risk of incident asthma. In addition, there was a dose-response effect of absolute weight gain on asthma incidence, independent of weight in early adulthood. The effects of weight gain on the annual odds of developing asthma were more pronounced in female than in male. The findings underscored the importance of prevention of weight gain in early adulthood, for reducing incident asthma risk in later life.\u003c/p\u003e \u003cp\u003ePrior epidemiological data on the relationship between adulthood weight change and asthma were sparse. The California Teachers Study (CTS) including 88 304 women observed that weight gain\u0026thinsp;\u0026ge;\u0026thinsp;5\u0026nbsp;kg since age 18\u0026nbsp;years was statistically significantly associated with increased prevalence of adult-onset asthma.[\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e] However, weight gain did not clearly precede the observed asthma, these results may have simply reflected antecedent asthma followed by activity limitation and weight gain. By assessing weight change from the ages of 25\u0026nbsp;years to the baseline, the current study attempted to capture the changes in BMI during adulthood before the asthma starts, and to minimize reverse causation. In our study, weight gain from a non-obesity to an obesity pattern since young adulthood had a 63% higher incident asthma risk. Extreme weight gain (\u0026ge;\u0026thinsp;20\u0026nbsp;kg) from early to middle adulthood was associated with a 53% higher incident asthma risk. Higher weight gain predicted subsequent incident asthma in some,[\u003cspan additionalcitationids=\"CR24\" citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e] but not all,[\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e] participants in the relevant prospective studies. Using data from the Nurses\u0026rsquo; Health Study (NHS) with 85 911 female nurses aged 26\u0026ndash;46\u0026nbsp;years at entry, Camargo et al. found that women who gained weight\u0026thinsp;\u0026gt;\u0026thinsp;10\u0026nbsp;kg after age 18 were at significantly increased risk of developing asthma during the 4-year follow-up period.[\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e] Similarly, during a 3-year follow-up period of 67 229 women aged 40\u0026ndash;65\u0026nbsp;years in the E3N Cohort Study, Romieu et al. reported that women who gained approximately\u0026thinsp;\u0026ge;\u0026thinsp;10\u0026nbsp;kg between the age of 20\u0026nbsp;years and baseline had a 89% increased risk of incident asthma.[\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e] Our results were consistent with these studies and indicated that avoiding obesity at young age and preventing weight gain from young to middle adulthood could be an important strategy to reduce future asthma risk.\u003c/p\u003e \u003cp\u003eWe also found evidence that weight gain was related to incident asthma in women but not men. A number of population-based studies have suggested that the relationship between obesity and asthma may be stronger in females.[\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e] Several possible mechanisms have been postulated to explain the obesity-asthma relationship. A sexual dimorphism exists in relation to body composition, in that females carry more fat subcutaneously and males carry more fat viscerally.[\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e] This led to distinct differences in the inflammatory pattern exhibited. For example, leptin is secreted more highly from subcutaneous adipose tissue and is therefore higher in females than males.[\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e] Compared to males, females have a smaller airway size relative to lung size.[\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e] An additional reduction in airway size caused by weight gain may disproportionately increase the susceptibility of females to asthma.[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e] The increased estrogen levels associated with obesity are also thought to be one mechanism to explain the strong association between female obesity and adult-onset asthma.\u003csup\u003e[28, 29]\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eIn our study, weight loss from young to middle adulthood was generally not significantly related to incident asthma compared with the stable normal group or stable obesity group. As weight loss from the obesity to the non-obesity among adulthood was rare, representing only 0.9% of the total population, and the results should be interpreted cautiously. More studies are needed to confirm the results in larger populations and explore the potential effect of weight loss among obesity people.\u003c/p\u003e \u003cp\u003eAdults gain weight more rapidly from young to middle adulthood, and excess adiposity mostly accrues in this period compared with the period from middle to late adulthood when weight begins to stabilize or even decrease.[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e] In addition, preventing weight gain from young to middle adulthood might be more important than promoting weight loss, because achieving long term weight loss and maintaining it are difficult once a person becomes obese.[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e] Evaluating the long term effect of weight change, particularly weight gain from early to middle adulthood, on future health is thus important. Weight gain from early to middle adulthood is a well-established risk factor for diabetes, hypertension, cardiovascular disease, cancer, non-traumatic death, and many other diseases.[\u003cspan additionalcitationids=\"CR15 CR16\" citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e] Our findings support adding asthma to this list and should provide yet one more piece of information to prevent weight gain and to support the aggressive implementation of public health measures to support the attainment of this goal.\u003c/p\u003e \u003cp\u003eWe used population attributable fraction to explore the potential effect of prevention initiatives targeting weight gain. If all those who were non-obesity at age 25 prevent weight gain by midlife, 10.2% of observed incident cases of adult-onset asthma could be averted. In total, we found that 21.8% of asthma new cases during this time period could be reduced if the entire population maintained a weight in the normal range between early and middle adulthood in U.S. adults.\u003c/p\u003e \u003cp\u003eOur study had several strengths. Using a retrospective cohort design, we were able to take advantage of a large, nationally representative cohort of U.S. adults to estimate associations between weight change and incident asthma across the life course. As a nationally representative survey, results using NHANES are more broadly generalizable than those from other cohorts like the NHS, CTS and E3N Cohort Study. The advantage of focusing on weight gain throughout adult life is that it primarily reflects the accumulation of excess adiposity from early to middle adulthood, which is often ignored by individuals and their physicians because the consequences of modest weight accumulation may not yet be apparent. If the association between early adulthood weight gain and adult-onset asthma is proved to be causal, understanding and preventing early adulthood weight gain would be the next steps in research and translation, which is not only beneficial to future cardio-metabolic health, but also to mitigation of future asthma risk.\u003c/p\u003e \u003cp\u003eOur study also had several limitations. Firstly, we used recalled and self-reported weight data at age 25\u0026nbsp;years and 10\u0026nbsp;years before the NHANES survey and thus misclassification bias might have been introduced. However, a recent meta-analysis showed that recalled early life weight could be a valid measure to use in life course epidemiological analysis.[\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e] Secondly, we could not adjust for physical activity or diet because recall data on these variables were not collected. The results might thus partly reflect the effects of physical activity and dietary factors over the life course. Thirdly, members of the relevant cohorts who had died before the survey were not represented in the retrospective data set. Their experience might have differed from that of survivors in ways that affected the estimated relationship between obesity and asthma. Furthermore, our report relied on self-reported data on asthma status, which may have missed people who had not been diagnosed with the condition. Lastly, we did not evaluate the relations of changes in other adiposity related markers such as waist circumference and fat mass with incident asthma owing to lack of data at different time points. Further studies with repeated data on these markers may provide a more comprehensive picture of the changes in obesity status and asthma risk.\u003c/p\u003e "},{"header":"Conclusions","content":" \u003cp\u003eOur study found that weight gain from young to middle adulthood was associated with increased risks of incident asthma in women but not men. Future studies are needed to unravel the mechanisms underlying the association between weight change across adulthood and adult -onset asthma, particularly the relations of changes in body composition to asthma. In addition, as weight loss was less achievable (only 0.9% participants changed from the obesity to the non-obesity category from early to middle adulthood), our results suggested that prevention of weight gain might be more important. If all those who were non-obesity at early adulthood prevented weight gain by midlife, approximately 10% of adult-onset asthma could be averted. Taken together, the findings indicated that maintaining normal weight throughout the adulthood, especially prevention of weight gain in early adulthood, should be encouraged to reduce risk of adult-onset asthma. Therefore, monitoring weight change since young adulthood could provide a sensitive and useful clinical measure for early detection of adverse trends in asthma risk.\u003c/p\u003e "},{"header":"Abbreviations","content":" \u003cp\u003eNHANES, National Health and Nutrition Examination Survey; NCHS, National Center for Health Statistics; CDC, Centers for Disease Control and Prevention; BMI, body mass index; PAF, population attributable fractions; CTS, California Teachers Study; NHS, Nurses\u0026rsquo; Health Study; E3N, Etude Epid\u0026eacute;miologique aupr\u0026egrave;s de femmes de l\u0026rsquo;Education Nationale.\u003c/p\u003e "},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTW, YPZ, and YXZ conceived of and designed the study; TW, YPZ, NK, and JZZ performed the data collection, management and analyses; TW and YPZ interpreted the results and drafted the manuscript; and GC and YXZ critically edited the manuscript. All authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work was supported by the National Key R\u0026amp;D Program of China of Ministry of Science and Technology of the People's Republic of China [2017YFC1600200]; National Natural Science Foundation of China [91643203]; and Postdoctoral Science Foundation of China [2019M660161]. The study funders had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; or decision to submit the manuscript for publication.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets generated and analysed during the current study are available at NHANES official website (https://wwwn.cdc.gov/nchs/nhanes/Default.aspx).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cbr /\u003e \u003c/strong\u003e\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eHales CM, Carroll MD, Fryar CD, Ogden CL. \u003cb\u003ePrevalence of Obesity and Severe Obesity Among Adults: United States, 2017\u0026ndash;2018\u003c/b\u003e. \u003cem\u003eNCHS data brief\u003c/em\u003e 2020:1\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAkinbami LJ, Fryar CD. \u003cb\u003eCurrent Asthma Prevalence by Weight Status Among Adults: United States, 2001\u0026ndash;2014\u003c/b\u003e. \u003cem\u003eNCHS data brief\u003c/em\u003e 2016:1\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBeuther DA, Sutherland ER. 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JAMA network open. 2019;2:e1917371.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZipf G, Chiappa M, Porter KS, Ostchega Y, Lewis BG, Dostal J. \u003cb\u003eNational health and nutrition examination survey: plan and operations, 1999\u0026ndash;2010.\u003c/b\u003e \u003cem\u003eVital and health statistics Ser 1, Programs and collection procedures\u003c/em\u003e 2013.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBerry KM, Neogi T, Baker JF, Collins JM, Waggoner JR, Hsiao C-W, Johnston SS, LaValley MP, Stokes A: \u003cb\u003eObesity Progression between Young Adulthood and Midlife and Incident Arthritis\u003c/b\u003e: \u003cb\u003eA Retrospective Cohort Study of US Adults\u003c/b\u003e. \u003cem\u003eArthritis care \u0026amp; research\u003c/em\u003e 2020.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhou Y, Wang T, Yin X, Sun Y, Seow WJ. \u003cb\u003eAssociation of Weight Loss from Early to Middle Adulthood and Incident Hypertension Risk Later in Life\u003c/b\u003e. \u003cem\u003eNutrients\u003c/em\u003e 2020, 12.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBundy JD, Mills KT, Chen J, Li C, Greenland P, He J. Estimating the Association of the 2017 and 2014 Hypertension Guidelines With Cardiovascular Events and Deaths in US Adults: An Analysis of National Data. JAMA cardiology. 2018;3:572\u0026ndash;81.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eVon Behren J, Lipsett M, Horn-Ross PL, Delfino RJ, Gilliland F, McConnell R, Bernstein L, Clarke CA, Reynolds P. Obesity, waist size and prevalence of current asthma in the California Teachers Study cohort. Thorax. 2009;64:889\u0026ndash;93.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCamargo CA, Weiss ST, Zhang S, Willett WC, Speizer FE. Prospective study of body mass index, weight change, and risk of adult-onset asthma in women. Arch Intern Med. 1999;159:2582\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBeckett WS, Jacobs DR, Yu X, Iribarren C, Williams OD. Asthma is associated with weight gain in females but not males, independent of physical activity. Am J Respir Crit Care Med. 2001;164:2045\u0026ndash;50.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRomieu I, Avenel V, Leynaert B, Kauffmann F, Clavel-Chapelon F. Body mass index, change in body silhouette, and risk of asthma in the E3N cohort study. Am J Epidemiol. 2003;158:165\u0026ndash;74.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHasler G, Gergen PJ, Ajdacic V, Gamma A, Eich D, R\u0026ouml;ssler W, Angst J. Asthma and body weight change: a 20-year prospective community study of young adults. Int J Obes. 2006;30:1111\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eScott HA, Gibson PG, Garg ML, Wood LG. Airway inflammation is augmented by obesity and fatty acids in asthma. Eur Respir J. 2011;38:594\u0026ndash;602.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHan Y-Y, Forno E, Celed\u0026oacute;n JC. Sex Steroid Hormones and Asthma in a Nationwide Study of U.S. Adults. Am J Respir Crit Care Med. 2020;201:158\u0026ndash;66.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCarey MA, Card JW, Voltz JW, Arbes SJ, Germolec DR, Korach KS, Zeldin DC. It's all about sex: gender, lung development and lung disease. Trends Endocrinol Metab. 2007;18:308\u0026ndash;13.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFontana L, Hu FB. Optimal body weight for health and longevity: bridging basic, clinical, and population research. Aging cell. 2014;13:391\u0026ndash;400.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDe Rubeis V, Bayat S, Griffith LE, Smith BT, Anderson LN. Validity of self-reported recall of anthropometric measures in early life: A systematic review and meta-analysis. Obesity reviews: an official journal of the International Association for the Study of Obesity. 2019;20:1426\u0026ndash;40.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":true,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"respiratory-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"rere","sideBox":"Learn more about [Respiratory Research](http://respiratory-research.biomedcentral.com/)","snPcode":"12931","submissionUrl":"https://submission.nature.com/new-submission/12931/3","title":"Respiratory Research","twitterHandle":"@RespiratoryBMC","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"asthma, body mass index, obesity, weight gain ","lastPublishedDoi":"10.21203/rs.3.rs-127866/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-127866/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground: \u003c/strong\u003eData describing the effects of weight change across adulthood on asthma are important for the prevention of asthma. This study aimed to investigate the association between weight change from early to middle adulthood and risk of incident asthma.\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eMethods: \u003c/strong\u003eUsing data from the National Health and Nutrition Examination Survey (NHANES), we performed a nationally retrospective cohort study of the U.S. general population. A total of 20 771 people aged 40-74 years with recalled weight at young and middle adulthood were included in the cohort. Hazard ratios relating weight change to incident asthma over 10 years of follow-up were calculated using Cox models adjusting for covariates.\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eResults:\u003c/strong\u003e Compared with participants with stable non-obesity between young and middle adulthood, the hazard ratios of incident asthma were 1.63 (95% confidence interval 1.29 to 2.07) for weight gain (non-obesity to obesity), 1.41 (0.97 to 2.05) for stable obesity, and 1.21 (0.41 to 3.62) for weight loss (obesity to non-obesity). In addition, participants who gained more than 20 kg had a hazard ratio of 1.53 (1.15 to 2.03), compared with those whose weight had remained stable. When stratified by sex, the association between weight gain and incident asthma was seen only in females. Population attributable fraction calculations estimated that 10.2% of adult-onset asthma could be averted, if all those who were non-obesity at early adulthood could prevent weight gain by midlife. \u003c/p\u003e\u003cp\u003e\u003cstrong\u003eConclusion: \u003c/strong\u003eThe findings implied that maintaining normal weight across adulthood, especially preventing weight gain in early adulthood, was important for preventing adult-onset asthma.\u003c/p\u003e","manuscriptTitle":"Weight Change from Early to Middle Adulthood and Incident Asthma Later in Life: A Retrospective Cohort Study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2020-12-15 23:55:10","doi":"10.21203/rs.3.rs-127866/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Major revision","date":"2021-02-07T00:00:00+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2021-01-24T00:00:00+00:00","index":2,"fulltext":"Recommendation: Reviewer's comments unavailable due to the journal's policy.\n"},{"type":"reviewerAgreed","content":"","date":"2021-01-10T00:00:00+00:00","index":2,"fulltext":""},{"type":"editorInvitedReview","content":"","date":"2020-12-28T00:00:00+00:00","index":1,"fulltext":"Recommendation: Reviewer's comments unavailable due to the journal's policy.\n"},{"type":"reviewerAgreed","content":"","date":"2020-12-12T00:00:00+00:00","index":1,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2020-12-10T00:00:00+00:00","index":"","fulltext":""},{"type":"submitted","content":"","date":"2020-12-09T00:00:00+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2020-12-09T00:00:00+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2020-12-08T23:00:00+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2020-12-08T23:00:00+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"respiratory-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"rere","sideBox":"Learn more about [Respiratory Research](http://respiratory-research.biomedcentral.com/)","snPcode":"12931","submissionUrl":"https://submission.nature.com/new-submission/12931/3","title":"Respiratory Research","twitterHandle":"@RespiratoryBMC","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"8e52315e-0dac-425f-9b6f-d606c1f676fd","owner":[],"postedDate":"December 15th, 2020","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[{"id":1495064,"name":"Health Economics \u0026 Outcomes Research"},{"id":1495065,"name":"Pulmonology"}],"tags":[],"updatedAt":"2021-06-13T22:40:06+00:00","versionOfRecord":[],"versionCreatedAt":"2020-12-15 23:55:10","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-127866","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-127866","identity":"rs-127866","version":["v1"]},"buildId":"_2-kVJe1T_tPrBINL-cwx","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}