Impact of supine body position on sleep-disordered breathing in MSA patients

Impact of supine body position on sleep-disordered breathing in MSA patients | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Impact of supine body position on sleep-disordered breathing in MSA patients Fang Xu, Hui Wang, Hongyan Huang, Qiuyan Shen, Dan Zhang, Yi Bao, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4753121/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 10 Dec, 2024 Read the published version in Clinical Autonomic Research → Version 1 posted 4 You are reading this latest preprint version Abstract Purpose Sleep-disordered breathing (SDB) is prevalent in multiple system atrophy (MSA) patients. Clinical observations suggest a predominance of supine sleep due to disabled mobility. This study aimed to assess the effect of supine position on SDB in MSA patients. Methods This cross-sectional study enrolled 104 "probable" MSA patients. Patients with apnea-hypopnea index (AHI) > 5/h were diagnosed with SDB. AHI in supine and lateral positions were compared. Association between supine sleep percentage and AHI was assessed using generalized linear model. Results The frequency of SDB was 84.6% (88/104) in MSA. Up to 51.9% (54/104) MSA patients spend more than 80% sleep time on supine position. Unified Multiple System Atrophy Rating Scale part II scores positively correlated with supine sleep percentage (r = 0.229, p = 0.019). After adjusting for age, sex, BMI, and UMSARS-II score, more supine position percentage predict higher AHI (β coefficient 0.122, 95% confidence interval 0.002–0.241). Among the 45 MSA-SDB patients with at least 30 minutes of data in both supine and lateral positions, 64.4% (29/45) exhibited positional sleep apnea (> 50% reduction in the AHI between the supine and the lateral position). The supine AHI was significantly higher than lateral AHI in MSA-SDB patients (21.0 [14.1, 29.6] /h vs. 9.4 [4.8, 15.3] /h, p < 0.001). Conclusion Supine sleep position is common in MSA and increases with more severe motor symptoms. Sleeping in supine position exacerbates respiratory events. Management of motor symptoms may help reduce supine position and improve SDB in MSA patients. Multiple system atrophy Sleep-disordered breathing Sleep position Supine Figures Figure 1 Introduction Multiple system atrophy (MSA) is a rare, rapidly progressing neurodegenerative disorder characterized by autonomic failure in combination with parkinsonism or cerebellar ataxia [ 1 ]. Sleep-disordered breathing (SDB) problems including stridor, central and obstructive sleep apnea are common comorbidities in patients with MSA and exacerbates with disease progression [ 2 , 3 ]. Stridor and severe sleep apnea are associated with an increased risk of sudden death during sleep and shorter survival in MSA patients [ 4 , 5 ]. It has long been recognized that in subjects with obstructive sleep apnea (OSA) from the general population, supine body position is associated with an elevated risk of upper airway collapse [ 6 ], increased frequency and duration of apneic events, and a greater need for higher pressures from Continuous Positive Airway Pressure (CPAP) devices [ 7 – 10 ]. Studies in central sleep apnea (CSA) patients with heart failure also revealed similar impact of supine body sleep [ 8 ]. It may seem reasonable to directly apply these findings to MSA patients with SDB. However, such extrapolation may not be valid as pathogenesis of SDB in MSA differs from that of OSA or CSA patients from general population. First, the development of SDB in MSA is influenced by both the degeneration of the pontomedullary respiratory centers and upper airway obstruction. Second, abnormal vocal cord movement also plays a role in inducing upper airway obstruction in MSA [ 3 ]. Considering that the effect of sleep position on the SDB is influenced by the complex interaction between body position and the underlying pathophysiological mechanisms of SDB [ 8 ], this effect may be different in MSA patients than in the general population. Positional effects on SDB in MSA patients were not investigated, and understanding of positional effects on SDB in MSA can contribute to the better clinical management. Therefore, we conducted a cross-sectional study to evaluate the influence of supine body position on SDB in MSA patients. Materials and methods Participants From 2016 to 2022, this cross-sectional study enrolled 104 consecutive patients with “Probable” MSA from the Department of Neurology, West China Hospital of Sichuan University. At least two experienced neurologists confirmed MSA diagnoses following second consensus statement on the diagnosis of MSA [ 11 ]. All patients underwent brain MRI scans to exclude other neurologic disorders. Patients were excluded if they used medications or substances that might affect their sleep cycle, such as hypnotic drugs, antidepressants, selective serotonin reuptake inhibitors, and antipsychotic agents. The study was approved by the West China Hospital Clinic Research Ethics Committee, and all patients provided written informed consent. Clinical assessment All patients underwent standardized evaluation during face-to-face interviews with trained neurologists. The patients were divided into MSA-P or MSA-C at the time of evaluation depending on their predominant symptoms. Clinical information including age, sex, age of onset, symptoms of onset, and disease duration were collected. Disease duration was defined as the time from the symptom of onset to the evaluation. Symptom of onset was defined as the initial presentation of any motor symptoms (i.e., parkinsonism or cerebellar ataxia) or autonomic features, except for male erectile dysfunction [ 11 ]. Orthostatic hypotension was defined as an orthostatic decrease in blood pressure within 3 min of standing by 30 mm Hg or 15 mm Hg in systolic or diastolic pressure, respectively. The disease severity was rated with part I (activities of daily living), part II (motor examination), part III (autonomic examination), and part IV (global disability) of the Unified Multiple System Atrophy Rating Scale (UMSARS) [ 12 ]. The total UMSARS score is the sum of parts I and II. The Non-Motor Symptoms Scale (NMSS) was used to evaluate the severity of non-motor symptoms. The severity of depression and anxiety were assessed, respectively, using the Hamilton Depression Rating scale (HAMD, 17 items) and Hamilton Anxiety Rating scale (HAMA). Subjective daytime sleepiness was assessed using Epworth Sleepiness Scale (ESS) scale. Fatigue was assessed using Fatigue Severity Scale (FSS) scale. Cognitive function was assessed using the Mini-Mental State Examination (MMSE) score. Sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI). Polysomnography All the enrolled patients underwent an overnight Polysomnography (PSG) in the Sleep Medicine Center of West China Hospital. The continuous recordings included electroencephalography (F4–M1, C4–M1, O2–M1, F3–M2, C3–M2, O1–M2), electrooculography (ROC–M1, LOC–M2), electromyography (chin and anterior tibialis muscles), electrocardiography, oxygen saturation by pulse oximetry with a finger probe, nasal-oral flow by a nasal pressure transducer. The body position sensor was placed over the midline of the chest wall and recognized distinct body positions by virtue of different voltage outputs. The PSG results were scored by experienced sleep technicians. The definition of apnea used in this study was a ≥ 90% decrease in the airflow signal from baseline that lasted for ≥ 10 seconds [ 13 ]. Hypopneas were identified as a ≥ 30% decrease in airflow (as measured by a valid airflow measure) lasting ≥ 10 seconds, accompanied by either a ≥ 3% desaturation from the pre-event baseline or an arousal [ 13 ]. The diagnosis of SDB was based on AHI > 5/h [ 13 ]. Apneas can be categorized into different types: obstructive apneas, which occur with continuous respiratory effort; central apnea, which occurs without evidence of respiratory effort; and mixed apneas, which initially present as central apneas and later transition to obstructive apneas with evidence of obstruction during the apneic interval. Data from the right and left positions were combined into a single lateral position. Patients with at least 30 minutes of PSG data in both the supine and lateral body positions [ 8 , 14 ] were included for further comparison sleep breathing parameters in different body position. Patients with SDB was categorized as having positional sleep apnea according to the Cartwright’s criteria, which defined it as a > 50% reduction in the apnea-hypopnea index (AHI) between the supine and lateral positions [ 7 ]. Statistical analysis One-sample Shapiro-Wilk tests were used to assess data normality. Descriptive statistics for normally and non-normally distributed data are reported as median (lower quartile, upper quartile) and mean ± SD, respectively. Categorical variables presented as numbers or percentages. For non-normally distributed data, between- and within-group comparisons were performed by the Mann–Whitney U-test and Wilcoxon signed-rank test, respectively. The unpaired and paired t-tests were used for normally distributed variables. Comparisons of categorical variables were carried out with the chi-squared and Fisher's exact tests. A generalized linear model was used to examine the association between supine body position percentage and AHI after adjusting for age, sex, UMSARS-II scores, and BMI. We calculated Pearson's r for correlation analysis of normally and Spearman-rho for non-normally distributed data. Statistical significance was set at P < 0.05. All analyses were performed with IBM SPSS (version 26.0) (IBM, Armonk, NY, USA). Results A total of 104 patients with MSA were enrolled, including 62 (59.6%) MSA-P and 58 (55.8%) male patients. The mean age of onset was 59.3 ± 9.9 years. The median disease duration was 2.0 (1.0, 3.0) years. Eighty-eight (84.6%) MSA individuals were diagnosed as having SDB. The proportion of SDB in MSA-P (52/62, 83.9%) and MSA-C (36/42, 85.7%) patients were similar. The comparison of the demographic and clinical features between MSA-SDB group and MSA-nSDB group are shown in Table 1 . There were no significant differences in age, age of onset, disease duration, UMSARS, NMSS, ESS, FSS, PSQI, MMSE, HAMA, and HAMD scores between the two groups. Compared with MSA-nSDB group, the male patient percentage and BMI are higher in the MSA-SDB group ( p < 0.05). Table 1 Demographic and clinical characteristics data of patients with MSA-SDB and MSA-nSDB Variables MSA (n = 104) MSA-nSDB (n = 16) MSA-SDB (n = 88) P Value Age, y 61.9 ± 9.9 59.8 ± 11.2 62.3 ± 9.7 0.369 Age at onset, y 59.3 ± 9.9 57.2 ± 11.1 59.7 ± 9.6 0.351 Male (%) 58 (55.8) 8 (25) 54 (61.4) 0.007* MSA-P (%) 62 (59.6) 10 (62.5) 52 (59.1) 0.798 Disease duration, y 2 (1, 3) 1.5 (1, 3.9) 2 (1, 3) 0.967 BMI, (kg/m2) 23.9 ± 3.2 21.7 ± 3 24.3 ± 3 0.006* UMSARS I 13.2 ± 6.1 13.8 ± 7.3 13.1 ± 5.9 0.683 UMSARS II 16.3 ± 6.9 17.7 ± 7.5 16 ± 6.8 0.38 UMSARS I + II 29.5 ± 11.9 31.5 ± 13.9 29.2 ± 11.6 0.476 NMSS 48.5 (27.3, 70.5) 48.5 (27.3, 62.5) 49 (27.3,71.8) 0.633 ESS 5.5 (3,10) 8.5 (3, 11.5) 5 (3, 9.8) 0.437 FSS 21 (10.5, 39.5) 19 (13, 47) 21 (10, 37.5) 0.244 PSQI 7 (4,11) 8 (5, 11.3) 7 (3, 11) 0.299 MMSE 27 (23, 28) 26 (23, 28.5) 27 (23.3, 28) 0.641 HAMA 9 (5,17) 8.5 (2.3, 18) 9 (5, 17) 0.685 HAMD 7 (4,16) 9.5 (3.3, 17.8) 7 (4, 13) 0.609 Data are presented as the mean ± SD, median (Q1, Q3), or number/total (%) BMI , Body mass index; ESS , Epworth Sleepiness Scales; FSS , Fatigue Severity Scale; HAMD , Hamilton Depression Scale; HAMA , Hamilton Anxiety Scale; MSA , Multiple system atrophy; MMSE , Mini-mental State Examination; NMSS , Non-Motor Symptoms Scale; PSQI , Pittsburgh Sleep Quality Index; SDB , Sleep-disordered breathing; UMSARS , Unified Multiple System Atrophy Rating Scale *p < 0.05 The comparison of the polysomnographic parameter between MSA-SDB group and MSA-nSDB group are shown in Table 2 . No significant differences were found between MSA patients with and without SDB in terms of total sleep time (TST), sleep efficiency (SE), sleep latency (SL), the percentages of N1, N2, and N3 sleep stage, WASO, arousal index, OAI and MAI. Compared with the MSA without SDB group, patients with MSA-SDB had a higher AHI, OAI, and HI ( p < 0.05), spent more time with an oxygen saturation below 90% ( p < 0.05), and lower mean oxygen saturation and minimum oxygen saturation ( p < 0.05). In addition, the MSA with SDB group had a lower percentage of REM sleep ( p < 0.05). A total of 51.9% (54/104) MSA patient spend more than 80% time on supine sleep position. Although MSA-SDB group had higher supine sleep percentage than MSA-nSDB group (81.4% VS. 71.9%), the difference did not reach statistical significance ( p = 0.073). As shown in Fig. 1, significant correlation was observed between UMSARS-II score and percentage of supine sleep ( r = 0.229, p = 0.019). Table 2 Polysomnographic parameters of patients with MSA-SDB and MSA-nSDB Variables MSA (n = 104) MSA-SDB (n = 88) MSA-nSDB (n = 16) P Value Total sleep time, min 352.8(296.8, 413.3) 354.9 (304.5, 415) 340.1 (272.4, 385.8) 0.531 Latency to sleep onset, min 11.3 (5.6, 29) 11.3 (6, 26.3) 10.8 (4.3, 34.6) 0.67 Sleep efficiency (%) 68.6 (58, 79) 69.3 (58.2, 79.6) 63.9 (53.8, 72.4) 0.328 NREM 1 (% TST) 25.7 (17.9,35.6) 27.1 (18.2, 39.1) 20.4 (17.6, 28.3) 0.21 NREM 2 (% TST) 50.8 ± 7.9 50.7 ± 15 51.5 ± 10.4 0.842 NREM 3 (% TST) 0 (0, 0.3) 0 (0, 0.9) 0 (0, 0) 0.186 REM (% TST) 18.8 ± 14.3 18 ± 7.5 22.9 ± 8.9 0.022* WASO, min 140.2 (88.7, 187.6) 135 (84, 186.6) 147.5 (107.7, 195.9) 0.38 Arousal index/h 15.4 (11.1, 21.8) 15.4 (10.9, 22.4) 15.4 (11.5, 20.2) 0.993 Supine body position (% TST) 80.6 (55.2, 99.8) 81.4 (58.8, 99.9) 71.9 (27.1, 97) 0.073 Supine body position > 80% 54 (51.9) 47 (53.4) 7 (43.8) 0.477 Lateral body position (% TST) 9.8 (0, 41) 8.6 (0, 30.7) 16.9 (0, 53.6) 0.3 AHI/h 14.35 (6.35, 27.15) 16.5 (8.93, 30.53) 2.5 (1.53, 4.4) < 0.001* CAI 0(0, 0.4) 0.1(0, 0.6) 0(0, 0.2) 0.18 OAI 0.9(0.1, 4.9) 1.5 (0.3, 5.9) 0.1(0, 0.3) < 0.001* MAI 0(0, 0.3) 0(0, 0.4) 0(0, 0.2) 0.197 HI 10.6(5.8, 19.3) 13.1 (7.2, 24.4) 2.2(1.1, 3.3) < 0.001* ODI 14 (5.4, 24.2) 16.15 (9.2, 31.3) 2.45 (1.4, 3.5) < 0.001* Minimum SaO2 86 (82, 90) 86 (82, 89) 91.5 (89, 92.8) < 0.001* Mean SaO2 94 (93, 95) 94 (92.3, 95) 95.5 (95, 96.8) < 0.001* Time SaO2 < 95% (min) 326 (112.7, 440.1) 353.8 (138.4, 451.7) 81 (5.3, 156.5) 0.002* Time SaO2 < 90% (min) 3.2(0.1, 18.1) 0.1 (0, 1.2) 0.1 (0, 0.3) < 0.001* Data are presented as the mean ± SD, median (Q1, Q3), or number/total (%) AHI , Apnea–hypopnea index; CAI , Central apnea index; HI , Hypopnea index; MSA , Multiple system atrophy; NREM , Non-rapid eye movement; OAI , Obstructive apnea index; REM , Rapid eye movement; SaO2 , Oxygen saturation; SDB , Sleep-disordered breathing; WASO , Wake time after sleep onset *p < 0.05 As shown in Table 3 , after adjusting for age, sex, UMSARS-II scores, and BMI, more supine body position is associated with higher AHI (β coefficient, 0.122, 95% confidence interval [CI], 0.002 to 0.241, p = 0.046). Table 3 A generalized linear model for analyzing the association between supine body sleep percentage and AHI in patients with MSA Variables β 95% CI P value Age, y 0.243 -0.102-0.588 0.168 Male 4.848 -1.614-11.311 0.141 BMI 0.962 -0.104-2.028 0.077 UMSARS-Ⅱ -0.37 -0.852-0.111 0.132 Supine body position (% TST) 0.122 0.003–0.241 0.046* BMI , Body mass index; UMSARS , Unified Multiple System Atrophy Rating Scale *p < 0.05 As shown in Table 4 , supine and lateral AHI were compared in 45 MSA-SDB patients with at least 30min of data in both the supine and lateral positions. When MSA-SDB patients moved from the supine to the lateral position, no significant differences were found in the CAI, MAI. However, the AHI, OAI, HI markedly and significantly decreased ( p < 0.05). A similar pattern was noted in the MSA-P and MSA-C subgroups. In addition, among the 45 MSA-SDB patients, 64.4% (29/45) were positional sleep apnea. Table 4 Comparison of the sleep breathing parameters between the supine and lateral positions in MSA patients with SDB MSA-SDB (n = 45) Supine Lateral P Value AHI 21 (14.1, 29.6) 9.4 (4.8, 15.3) < 0.001* OAI 1 (0.3, 5.6) 0 (0, 0.7) < 0.001* CAI 0 (0, 0.5) 0 (0, 0.2) 0.103 MAI 0 (0, 0.4) 0 (0, 0.2) 0.156 HI 17.5 (10.8, 23.9) 8.1 (3.8, 12.7) < 0.001* Data are presented as the median (Q1, Q3) AHI , Apnea–hypopnea index; CAI , Central apnea index; HI , Hypopnea index; MSA , Multiple system atrophy; OAI , Obstructive apnea index; SDB , Sleep-disordered breathing *p < 0.05 Discussion The present study demonstrated for the first time that most MSA patients are bound to supine body position. Sleeping in the supine body position is associated with more severe motor symptoms and deterioration in AHI in MSA patients with SDB. The overall prevalence of SDB (AHI > 5/h) was 84.6%, 83.9%, 85.7% in patients with MSA, MSA-P, and MSA-C, respectively. The prevalence in this study is higher compared to previous report that SDB was reported in 15.4% of 39 Italian MSA patients using AHI > 5/h as the diagnostic threshold [ 15 ], and higher than that in 36.8% of 19 MSA patients in 2004 using ODI > 10 as the diagnostic threshold [ 16 ]. The high prevalence of SDB recorded in our sample might be attributable to the increased sensitivity of current recording techniques and scoring criteria. Similar proportions (80% and 85%) were found in 15 and 34 MSA patients in 2010 and in 2022, respectively [ 17 , 18 ], using AHI ≥ 5/h. In this study, the prevalence of SDB in male patients was found higher than that in female patients. After adjusting for sex and age, higher BMI was an independent predictor of SDB in MSA, consistent with previous findings in the general population [ 19 , 20 ], these results suggest that high BMI and being male are associated with the presence of SDB in MSA. Previous studies have yielded conflicting results regarding the relationship between BMI and MSA-SDB. While a small-sample study did not find significant differences in BMI between MSA-SDB and MSA-nSDB patients, it did indicate an overall upward trend in BMI among patients with MSA-SDB [ 21 ]. Additionally, a separate investigation reported a high BMI in MSA patients with obstructive sleep apnea syndrome (OSAS), with an average BMI of 25.9 beyond the normal range [ 16 ]. Moreover, a decrease in BMI has been linked to spontaneous improvement of sleep-disordered breathing in MSA patients [ 22 ]. Our findings highlight that MSA patients tend to spend approximately 80% of their sleep time in supine position, and increased supine sleep is associated with higher UMSARS-II score, indicating impaired nocturnal mobility. The results align with previous PSG studies demonstrated that up to two thirds of acute stroke patients spend nearly their entire first nights in supine position, while the extent of supine sleep tends to decrease following recovery [ 23 ]. In addition, Parkinson's disease (PD) patients have been found to slept twice as much in supine position compared to control subjects, and longer PD disease duration was an independent predictor of more supine sleep [ 24 ]. PD patients with severe obstructive sleep apnea syndrome spent the majority of their sleep time in the supine position (93%) [ 25 ]. Consistent with prior research on patients with OSA that supine position increased frequency and duration of apneic events [ 10 , 26 ], our findings revealed a significant increase in the frequency of obstructive respiratory events when transitioning from the lateral to the supine position among MSA-SDB patients. OSA is characterized by recurrent of the upper airway obstruction during sleep, with the most severe and frequent events observed in the supine sleeping position. The identified mechanism including unfavorable airway geometry, reduced lung volume, and an inability of airway dilator muscles to adequately compensate as the airway collapses, arousal threshold and ventilatory control instability [ 26 ]. The similar impact pattern of supine body position suggests a common pathogenesis of supine upper airway obstruction in both MSA and the general population. We did not observe significant postural effects on the central and mixed respiratory events. which contrasts with the findings of a previous study that demonstrated the attenuation of central sleep apnea severity in patients with heart failure when in the lateral position [ 27 ]. Central sleep apnea is commonly recognized as a prominent feature in MSA, but it typically manifests in the later stages of the disease due to destruction of medullary chemoreceptors [ 28 , 29 ], or it may arise after elimination of upper airway obstruction through CPAP. Given that most MSA patients in our study were in early stages and primarily exhibited untreated obstructive respiratory events, the data on central events were limited, which may restrict the statistical power to evaluate the impact of supine body position on central sleep apnea. Continuous positive airway pressure (CPAP) and tracheotomy are the established treatments for alleviating obstructive sleep apneas in MSA [ 30 , 31 ]. CPAP is a non-invasive method that works by delivering a constant flow of air through a mask to maintain open airways during sleep, it can reduce the risk of infections and other complications associated with surgical interventions. However, its efficacy is highly dependent on patient compliance. The long-term acceptance of CPAP in MSA patients was poor, up to 66% MSA patients discontinued CPAP treatment with median treatment duration of 13.0 months [ 31 , 32 ]. This reduced adherence to CPAP may be attributed to motor impairment and the frequently observed floppy epiglottis. In such cases, CPAP can potentially exacerbate upper airway obstruction and pose a risk of suffocation [ 33 ]. Tracheostomy can also exacerbate central apneas in MSA, potentially caused by hyperventilation-induced hypocapnia [ 34 ]. Positional therapy (the avoidance of the supine position during sleep) has been proposed as a therapeutic strategy in OSA patients from the general population with positional sleep apnea [ 26 ], it might be considered as an alternative option to CPAP in MSA patients especially those failure to adhere CPAP treatment albeit may not a radical solution. Given that excessive supine recumbency seem to be consequence of motor impairment, effective management of nocturnal immobility through physical or pharmacological interventions becomes crucial for optimizing the management of SDB in MSA. This study has several limitations. First, as this is an observational study, we cannot prove the benefit of lateral body position on SDB in MSA. Interpreting the effect of positional therapy requires further research. Second, we cannot explain the pathophysiologic traits in supine body position in MSA patients. Third, we lacked a control group for comparing the supine body position percentage. Fourth, most patient were in early stage and presented with relatively low number of central apneas, limited the statistical power to fully evaluate the impact of supine body position on central sleep apnea, postural effect worth further investigation in MSA-CSA patients. In conclusion, an increased supine sleep position in people with MSA seems to be an important factor associated with SDB. Our study emphasizes the need for treatment strategies at night to implementing nighttime treatment strategies to reduce excessive supine recumbency in MSA patients, which may ultimately lead to improvements in SDB management in this population. Declarations Conflicts of interest None of the authors have any conflicts of interest to declare. Funding This work was funded by Department of Science and Technology of Sichuan (2023YFS0268 to YMX). Author contributions FX, HW and YMX conceived the idea of the study; HW and FX analyzed the data; HYH, YQS, YB, DZ, HW contributed data acquisition; JYZ interpreted the results; FX and HW wrote the paper; all authors discussed the results and revised the manuscript. Acknowledgements We would like to thank the study participants and the staff of the Sleep Medicine Center of West China Hospital. 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Mov Disord 22:155–161 Ralls F, Cutchen L (2020) Respiratory and sleep-related complications of multiple system atrophy. Curr Opin Pulm Med 26:615–622 Chang HJ, Kim HJ, Woo KA, Shin JH, Jung KY (2023) The effect of continuous positive airway pressure (CPAP) on the quality of life in patients with multiple system atrophy. Sleep Breath 27:1481–1484 Ghorayeb I, Yekhlef F, Bioulac B, Tison F (2005) Continuous positive airway pressure for sleep-related breathing disorders in multiple system atrophy: long-term acceptance. Sleep Med 6:359–362 Shimohata T, Nakayama H, Aizawa N, Nishizawa M (2014) Discontinuation of continuous positive airway pressure treatment in multiple system atrophy. Sleep Med 15:1147–1149 Shimohata T, Tomita M, Nakayama H, Aizawa N, Ozawa T, Nishizawa M (2011) Floppy epiglottis as a contraindication of CPAP in patients with multiple system atrophy. Neurology 76:1841–1842 Jin K, Okabe S, Chida K et al (2007) Tracheostomy can fatally exacerbate sleep-disordered breathing in multiple system atrophy. Neurology 68:1618–1621 Cite Share Download PDF Status: Published Journal Publication published 10 Dec, 2024 Read the published version in Clinical Autonomic Research → Version 1 posted Reviewers agreed at journal 04 Aug, 2024 Reviewers invited by journal 03 Aug, 2024 Editor assigned by journal 18 Jul, 2024 First submitted to journal 17 Jul, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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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-4753121","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":335607140,"identity":"e77e2ade-e228-444e-9e27-d5b8b8ddf907","order_by":0,"name":"Fang Xu","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAx0lEQVRIie3QMQrCMBSA4VcCzyXaNUFRjxAIdOpNXNKlk+4OAQtCHbv2GIIXCATiIniFeoN6ATGrgyRuDvnn9/F4DyCV+sfI1Zhxr5c5IXaII7itHv3NSX7CWkQSJeW0JdX5TtcsSggHNe8Rs4ulIECXmyDhbebYSBeksFMzgKt3TYjkq8ZvYYiFnSmRNTZMEKGYU0GoPFLBokiOICVVhHkVSXhL/ZONE8z6J6uYW4SbGPN86UPXWTuMugyTz9Rv46lUKpX61huavzxogxfnwQAAAABJRU5ErkJggg==","orcid":"","institution":"West China Hospital of Sichuan University","correspondingAuthor":true,"prefix":"","firstName":"Fang","middleName":"","lastName":"Xu","suffix":""},{"id":335607141,"identity":"9704d847-ee1d-4b14-80ec-04ffc80fc7f8","order_by":1,"name":"Hui Wang","email":"","orcid":"","institution":"Sichuan Taikang Yiyuan: Sichuan Taikang Hospital Co Ltd","correspondingAuthor":false,"prefix":"","firstName":"Hui","middleName":"","lastName":"Wang","suffix":""},{"id":335607142,"identity":"b977e1f5-a37a-4c58-80ae-b26ace523fb7","order_by":2,"name":"Hongyan Huang","email":"","orcid":"","institution":"West China Hospital of Sichuan University","correspondingAuthor":false,"prefix":"","firstName":"Hongyan","middleName":"","lastName":"Huang","suffix":""},{"id":335607143,"identity":"b29fe1bf-901d-4be5-a9a8-1674befd2eaf","order_by":3,"name":"Qiuyan Shen","email":"","orcid":"","institution":"West China Hospital of Sichuan University","correspondingAuthor":false,"prefix":"","firstName":"Qiuyan","middleName":"","lastName":"Shen","suffix":""},{"id":335607144,"identity":"b122d10d-de4f-4d5b-9332-da37eb87a20e","order_by":4,"name":"Dan Zhang","email":"","orcid":"","institution":"West China Hospital of Sichuan University","correspondingAuthor":false,"prefix":"","firstName":"Dan","middleName":"","lastName":"Zhang","suffix":""},{"id":335607145,"identity":"8f14ee9d-25b6-4d11-b22b-2b5c4135b2b6","order_by":5,"name":"Yi Bao","email":"","orcid":"","institution":"West China Hospital of Sichuan University","correspondingAuthor":false,"prefix":"","firstName":"Yi","middleName":"","lastName":"Bao","suffix":""},{"id":335607146,"identity":"26034f04-29bb-404a-9e82-f8cd8fbee658","order_by":6,"name":"Junying Zhou","email":"","orcid":"","institution":"West China Hospital of Sichuan University","correspondingAuthor":false,"prefix":"","firstName":"Junying","middleName":"","lastName":"Zhou","suffix":""},{"id":335607147,"identity":"4e9eaadd-5e00-465a-981b-6b1bf1a69638","order_by":7,"name":"Yanming Xu","email":"","orcid":"https://orcid.org/0000-0001-7908-235X","institution":"West China Hospital of Sichuan University","correspondingAuthor":false,"prefix":"","firstName":"Yanming","middleName":"","lastName":"Xu","suffix":""}],"badges":[],"createdAt":"2024-07-17 03:02:38","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4753121/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4753121/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s10286-024-01099-0","type":"published","date":"2024-12-10T15:57:53+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":64191059,"identity":"6e33c393-688c-45c4-a80a-0b79e0720521","added_by":"auto","created_at":"2024-09-09 18:33:15","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":135427,"visible":true,"origin":"","legend":"\u003cp\u003eLegend not included with this version.\u003c/p\u003e","description":"","filename":"Fig1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4753121/v1/53cba32ce12a28a646c6a0a0.jpg"},{"id":71552779,"identity":"e09f0a99-14ea-4e98-b893-f4758a3d3659","added_by":"auto","created_at":"2024-12-16 16:07:47","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":667594,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4753121/v1/7b46bca9-6b54-44c9-a46d-9be1742c42ea.pdf"}],"financialInterests":"","formattedTitle":"Impact of supine body position on sleep-disordered breathing in MSA patients","fulltext":[{"header":"Introduction","content":"\u003cp\u003eMultiple system atrophy (MSA) is a rare, rapidly progressing neurodegenerative disorder characterized by autonomic failure in combination with parkinsonism or cerebellar ataxia [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Sleep-disordered breathing (SDB) problems including stridor, central and obstructive sleep apnea are common comorbidities in patients with MSA and exacerbates with disease progression [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Stridor and severe sleep apnea are associated with an increased risk of sudden death during sleep and shorter survival in MSA patients [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIt has long been recognized that in subjects with obstructive sleep apnea (OSA) from the general population, supine body position is associated with an elevated risk of upper airway collapse [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e], increased frequency and duration of apneic events, and a greater need for higher pressures from Continuous Positive Airway Pressure (CPAP) devices [\u003cspan additionalcitationids=\"CR8 CR9\" citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Studies in central sleep apnea (CSA) patients with heart failure also revealed similar impact of supine body sleep [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIt may seem reasonable to directly apply these findings to MSA patients with SDB. However, such extrapolation may not be valid as pathogenesis of SDB in MSA differs from that of OSA or CSA patients from general population. First, the development of SDB in MSA is influenced by both the degeneration of the pontomedullary respiratory centers and upper airway obstruction. Second, abnormal vocal cord movement also plays a role in inducing upper airway obstruction in MSA [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Considering that the effect of sleep position on the SDB is influenced by the complex interaction between body position and the underlying pathophysiological mechanisms of SDB [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e], this effect may be different in MSA patients than in the general population.\u003c/p\u003e \u003cp\u003ePositional effects on SDB in MSA patients were not investigated, and understanding of positional effects on SDB in MSA can contribute to the better clinical management. Therefore, we conducted a cross-sectional study to evaluate the influence of supine body position on SDB in MSA patients.\u003c/p\u003e"},{"header":"Materials and methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eParticipants\u003c/h2\u003e \u003cp\u003eFrom 2016 to 2022, this cross-sectional study enrolled 104 consecutive patients with \u0026ldquo;Probable\u0026rdquo; MSA from the Department of Neurology, West China Hospital of Sichuan University. At least two experienced neurologists confirmed MSA diagnoses following second consensus statement on the diagnosis of MSA [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. All patients underwent brain MRI scans to exclude other neurologic disorders. Patients were excluded if they used medications or substances that might affect their sleep cycle, such as hypnotic drugs, antidepressants, selective serotonin reuptake inhibitors, and antipsychotic agents. The study was approved by the West China Hospital Clinic Research Ethics Committee, and all patients provided written informed consent.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eClinical assessment\u003c/h3\u003e\n\u003cp\u003eAll patients underwent standardized evaluation during face-to-face interviews with trained neurologists. The patients were divided into MSA-P or MSA-C at the time of evaluation depending on their predominant symptoms. Clinical information including age, sex, age of onset, symptoms of onset, and disease duration were collected. Disease duration was defined as the time from the symptom of onset to the evaluation. Symptom of onset was defined as the initial presentation of any motor symptoms (i.e., parkinsonism or cerebellar ataxia) or autonomic features, except for male erectile dysfunction [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Orthostatic hypotension was defined as an orthostatic decrease in blood pressure within 3 min of standing by 30 mm Hg or 15 mm Hg in systolic or diastolic pressure, respectively. The disease severity was rated with part I (activities of daily living), part II (motor examination), part III (autonomic examination), and part IV (global disability) of the Unified Multiple System Atrophy Rating Scale (UMSARS) [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. The total UMSARS score is the sum of parts I and II. The Non-Motor Symptoms Scale (NMSS) was used to evaluate the severity of non-motor symptoms. The severity of depression and anxiety were assessed, respectively, using the Hamilton Depression Rating scale (HAMD, 17 items) and Hamilton Anxiety Rating scale (HAMA). Subjective daytime sleepiness was assessed using Epworth Sleepiness Scale (ESS) scale. Fatigue was assessed using Fatigue Severity Scale (FSS) scale. Cognitive function was assessed using the Mini-Mental State Examination (MMSE) score. Sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI).\u003c/p\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003ePolysomnography\u003c/h2\u003e \u003cp\u003eAll the enrolled patients underwent an overnight Polysomnography (PSG) in the Sleep Medicine Center of West China Hospital. The continuous recordings included electroencephalography (F4\u0026ndash;M1, C4\u0026ndash;M1, O2\u0026ndash;M1, F3\u0026ndash;M2, C3\u0026ndash;M2, O1\u0026ndash;M2), electrooculography (ROC\u0026ndash;M1, LOC\u0026ndash;M2), electromyography (chin and anterior tibialis muscles), electrocardiography, oxygen saturation by pulse oximetry with a finger probe, nasal-oral flow by a nasal pressure transducer. The body position sensor was placed over the midline of the chest wall and recognized distinct body positions by virtue of different voltage outputs. The PSG results were scored by experienced sleep technicians. The definition of apnea used in this study was a\u0026thinsp;\u0026ge;\u0026thinsp;90% decrease in the airflow signal from baseline that lasted for \u0026ge;\u0026thinsp;10 seconds [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Hypopneas were identified as a\u0026thinsp;\u0026ge;\u0026thinsp;30% decrease in airflow (as measured by a valid airflow measure) lasting\u0026thinsp;\u0026ge;\u0026thinsp;10 seconds, accompanied by either a\u0026thinsp;\u0026ge;\u0026thinsp;3% desaturation from the pre-event baseline or an arousal [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. The diagnosis of SDB was based on AHI\u0026thinsp;\u0026gt;\u0026thinsp;5/h [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Apneas can be categorized into different types: obstructive apneas, which occur with continuous respiratory effort; central apnea, which occurs without evidence of respiratory effort; and mixed apneas, which initially present as central apneas and later transition to obstructive apneas with evidence of obstruction during the apneic interval.\u003c/p\u003e \u003cp\u003eData from the right and left positions were combined into a single lateral position. Patients with at least 30 minutes of PSG data in both the supine and lateral body positions [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e] were included for further comparison sleep breathing parameters in different body position. Patients with SDB was categorized as having positional sleep apnea according to the Cartwright\u0026rsquo;s criteria, which defined it as a\u0026thinsp;\u0026gt;\u0026thinsp;50% reduction in the apnea-hypopnea index (AHI) between the supine and lateral positions [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e].\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eOne-sample Shapiro-Wilk tests were used to assess data normality. Descriptive statistics for normally and non-normally distributed data are reported as median (lower quartile, upper quartile) and mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD, respectively. Categorical variables presented as numbers or percentages. For non-normally distributed data, between- and within-group comparisons were performed by the Mann\u0026ndash;Whitney U-test and Wilcoxon signed-rank test, respectively. The unpaired and paired t-tests were used for normally distributed variables. Comparisons of categorical variables were carried out with the chi-squared and Fisher's exact tests. A generalized linear model was used to examine the association between supine body position percentage and AHI after adjusting for age, sex, UMSARS-II scores, and BMI. We calculated Pearson's r for correlation analysis of normally and Spearman-rho for non-normally distributed data. Statistical significance was set at P\u0026thinsp;\u0026lt;\u0026thinsp;0.05. All analyses were performed with IBM SPSS (version 26.0) (IBM, Armonk, NY, USA).\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eA total of 104 patients with MSA were enrolled, including 62 (59.6%) MSA-P and 58 (55.8%) male patients. The mean age of onset was 59.3\u0026thinsp;\u0026plusmn;\u0026thinsp;9.9 years. The median disease duration was 2.0 (1.0, 3.0) years. Eighty-eight (84.6%) MSA individuals were diagnosed as having SDB. The proportion of SDB in MSA-P (52/62, 83.9%) and MSA-C (36/42, 85.7%) patients were similar.\u003c/p\u003e \u003cp\u003eThe comparison of the demographic and clinical features between MSA-SDB group and MSA-nSDB group are shown in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. There were no significant differences in age, age of onset, disease duration, UMSARS, NMSS, ESS, FSS, PSQI, MMSE, HAMA, and HAMD scores between the two groups. Compared with MSA-nSDB group, the male patient percentage and BMI are higher in the MSA-SDB group (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05).\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\u003eDemographic and clinical characteristics data of patients with MSA-SDB and MSA-nSDB\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVariables\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMSA \u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;104)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMSA-nSDB\u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;16)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eMSA-SDB\u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;88)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e Value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge, y\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e61.9\u0026thinsp;\u0026plusmn;\u0026thinsp;9.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e59.8\u0026thinsp;\u0026plusmn;\u0026thinsp;11.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e62.3\u0026thinsp;\u0026plusmn;\u0026thinsp;9.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.369\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge at onset, y\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e59.3\u0026thinsp;\u0026plusmn;\u0026thinsp;9.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e57.2\u0026thinsp;\u0026plusmn;\u0026thinsp;11.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e59.7\u0026thinsp;\u0026plusmn;\u0026thinsp;9.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.351\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMale (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e58 (55.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e8 (25)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e54 (61.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.007*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMSA-P (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e62 (59.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e10 (62.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e52 (59.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.798\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDisease duration, y\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2 (1, 3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.5 (1, 3.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2 (1, 3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.967\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBMI, (kg/m2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e23.9\u0026thinsp;\u0026plusmn;\u0026thinsp;3.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e21.7\u0026thinsp;\u0026plusmn;\u0026thinsp;3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e24.3\u0026thinsp;\u0026plusmn;\u0026thinsp;3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.006*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eUMSARS I\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e13.2\u0026thinsp;\u0026plusmn;\u0026thinsp;6.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e13.8\u0026thinsp;\u0026plusmn;\u0026thinsp;7.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e13.1\u0026thinsp;\u0026plusmn;\u0026thinsp;5.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.683\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eUMSARS II\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e16.3\u0026thinsp;\u0026plusmn;\u0026thinsp;6.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e17.7\u0026thinsp;\u0026plusmn;\u0026thinsp;7.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e16\u0026thinsp;\u0026plusmn;\u0026thinsp;6.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.38\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eUMSARS I\u0026thinsp;+\u0026thinsp;II\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e29.5\u0026thinsp;\u0026plusmn;\u0026thinsp;11.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e31.5\u0026thinsp;\u0026plusmn;\u0026thinsp;13.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e29.2\u0026thinsp;\u0026plusmn;\u0026thinsp;11.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.476\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNMSS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e48.5 (27.3, 70.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e48.5 (27.3, 62.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e49 (27.3,71.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.633\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eESS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5.5 (3,10)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e8.5 (3, 11.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5 (3, 9.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.437\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFSS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e21 (10.5, 39.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e19 (13, 47)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e21 (10, 37.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.244\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePSQI\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7 (4,11)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e8 (5, 11.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7 (3, 11)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.299\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMMSE\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e27 (23, 28)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e26 (23, 28.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e27 (23.3, 28)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.641\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHAMA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e9 (5,17)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e8.5 (2.3, 18)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e9 (5, 17)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.685\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHAMD\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7 (4,16)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e9.5 (3.3, 17.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7 (4, 13)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.609\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003eData are presented as the mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD, median (Q1, Q3), or number/total (%)\u003c/td\u003e\u003c/tr\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003e\u003cem\u003eBMI\u003c/em\u003e, Body mass index; \u003cem\u003eESS\u003c/em\u003e, Epworth Sleepiness Scales; \u003cem\u003eFSS\u003c/em\u003e, Fatigue Severity Scale; \u003cem\u003eHAMD\u003c/em\u003e, Hamilton Depression Scale; \u003cem\u003eHAMA\u003c/em\u003e, Hamilton Anxiety Scale; \u003cem\u003eMSA\u003c/em\u003e, Multiple system atrophy; \u003cem\u003eMMSE\u003c/em\u003e, Mini-mental State Examination; \u003cem\u003eNMSS\u003c/em\u003e, Non-Motor Symptoms Scale; \u003cem\u003ePSQI\u003c/em\u003e, Pittsburgh Sleep Quality Index; \u003cem\u003eSDB\u003c/em\u003e, Sleep-disordered breathing; \u003cem\u003eUMSARS\u003c/em\u003e, Unified Multiple System Atrophy Rating Scale\u003c/td\u003e\u003c/tr\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003e*p\u0026thinsp;\u0026lt;\u0026thinsp;0.05\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eThe comparison of the polysomnographic parameter between MSA-SDB group and MSA-nSDB group are shown in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. No significant differences were found between MSA patients with and without SDB in terms of total sleep time (TST), sleep efficiency (SE), sleep latency (SL), the percentages of N1, N2, and N3 sleep stage, WASO, arousal index, OAI and MAI. Compared with the MSA without SDB group, patients with MSA-SDB had a higher AHI, OAI, and HI (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05), spent more time with an oxygen saturation below 90% (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05), and lower mean oxygen saturation and minimum oxygen saturation (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05). In addition, the MSA with SDB group had a lower percentage of REM sleep (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05). A total of 51.9% (54/104) MSA patient spend more than 80% time on supine sleep position. Although MSA-SDB group had higher supine sleep percentage than MSA-nSDB group (81.4% VS. 71.9%), the difference did not reach statistical significance (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.073). As shown in Fig.\u0026nbsp;1, significant correlation was observed between UMSARS-II score and percentage of supine sleep (\u003cem\u003er\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.229, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.019).\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\u003ePolysomnographic parameters of patients with MSA-SDB and MSA-nSDB\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVariables\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMSA \u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;104)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMSA-SDB\u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;88)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eMSA-nSDB\u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;16)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e Value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTotal sleep time, min\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e352.8(296.8, 413.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e354.9 (304.5, 415)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e340.1 (272.4, 385.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.531\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLatency to sleep onset, min\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e11.3 (5.6, 29)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e11.3 (6, 26.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e10.8 (4.3, 34.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.67\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSleep efficiency (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e68.6 (58, 79)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e69.3 (58.2, 79.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e63.9 (53.8, 72.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.328\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNREM 1 (% TST)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e25.7 (17.9,35.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e27.1 (18.2, 39.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e20.4 (17.6, 28.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.21\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNREM 2 (% TST)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e50.8\u0026thinsp;\u0026plusmn;\u0026thinsp;7.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e50.7\u0026thinsp;\u0026plusmn;\u0026thinsp;15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e51.5\u0026thinsp;\u0026plusmn;\u0026thinsp;10.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.842\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNREM 3 (% TST)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0 (0, 0.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0 (0, 0.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0 (0, 0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.186\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eREM (% TST)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e18.8\u0026thinsp;\u0026plusmn;\u0026thinsp;14.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e18\u0026thinsp;\u0026plusmn;\u0026thinsp;7.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e22.9\u0026thinsp;\u0026plusmn;\u0026thinsp;8.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.022*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWASO, min\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e140.2 (88.7, 187.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e135 (84, 186.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e147.5 (107.7, 195.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.38\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eArousal index/h\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e15.4 (11.1, 21.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e15.4 (10.9, 22.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e15.4 (11.5, 20.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.993\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSupine body position (% TST)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e80.6 (55.2, 99.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e81.4 (58.8, 99.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e71.9 (27.1, 97)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.073\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSupine body position\u0026thinsp;\u0026gt;\u0026thinsp;80%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e54 (51.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e47 (53.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7 (43.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.477\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLateral body position (% TST)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e9.8 (0, 41)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e8.6 (0, 30.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e16.9 (0, 53.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAHI/h\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e14.35 (6.35, 27.15)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e16.5 (8.93, 30.53)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2.5 (1.53, 4.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\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\u003eCAI\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0(0, 0.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.1(0, 0.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0(0, 0.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.18\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOAI\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.9(0.1, 4.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.5 (0.3, 5.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.1(0, 0.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\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\u003eMAI\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0(0, 0.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0(0, 0.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0(0, 0.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.197\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHI\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10.6(5.8, 19.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e13.1 (7.2, 24.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2.2(1.1, 3.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\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\u003eODI\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e14 (5.4, 24.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e16.15 (9.2, 31.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2.45 (1.4, 3.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\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\u003eMinimum SaO2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e86 (82, 90)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e86 (82, 89)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e91.5 (89, 92.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\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\u003eMean SaO2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e94 (93, 95)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e94 (92.3, 95)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e95.5 (95, 96.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\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\u003eTime SaO2\u0026thinsp;\u0026lt;\u0026thinsp;95% (min)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e326 (112.7, 440.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e353.8 (138.4, 451.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e81 (5.3, 156.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.002*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTime SaO2\u0026thinsp;\u0026lt;\u0026thinsp;90% (min)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3.2(0.1, 18.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.1 (0, 1.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.1 (0, 0.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003eData are presented as the mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD, median (Q1, Q3), or number/total (%)\u003c/td\u003e\u003c/tr\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003e\u003cem\u003eAHI\u003c/em\u003e, Apnea\u0026ndash;hypopnea index; \u003cem\u003eCAI\u003c/em\u003e, Central apnea index; \u003cem\u003eHI\u003c/em\u003e, Hypopnea index; \u003cem\u003eMSA\u003c/em\u003e, Multiple system atrophy; \u003cem\u003eNREM\u003c/em\u003e, Non-rapid eye movement; \u003cem\u003eOAI\u003c/em\u003e, Obstructive apnea index; \u003cem\u003eREM\u003c/em\u003e, Rapid eye movement; \u003cem\u003eSaO2\u003c/em\u003e, Oxygen saturation; \u003cem\u003eSDB\u003c/em\u003e, Sleep-disordered breathing; \u003cem\u003eWASO\u003c/em\u003e, Wake time after sleep onset\u003c/td\u003e\u003c/tr\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003e*p\u0026thinsp;\u0026lt;\u0026thinsp;0.05\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eAs shown in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, after adjusting for age, sex, UMSARS-II scores, and BMI, more supine body position is associated with higher AHI (β coefficient, 0.122, 95% confidence interval [CI], 0.002 to 0.241, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.046).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eA generalized linear model for analyzing the association between supine body sleep percentage and AHI in patients with MSA\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVariables\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eβ\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e95% CI\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge, y\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.243\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-0.102-0.588\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.168\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e4.848\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-1.614-11.311\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.141\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBMI\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.962\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-0.104-2.028\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.077\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eUMSARS-Ⅱ\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e-0.37\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-0.852-0.111\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.132\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSupine body position (% TST)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.122\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.003\u0026ndash;0.241\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.046*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"4\"\u003e\u003cem\u003eBMI\u003c/em\u003e, Body mass index; \u003cem\u003eUMSARS\u003c/em\u003e, Unified Multiple System Atrophy Rating Scale\u003c/td\u003e\u003c/tr\u003e \u003ctr\u003e\u003ctd colspan=\"4\"\u003e*p\u0026thinsp;\u0026lt;\u0026thinsp;0.05\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eAs shown in Table \u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e, supine and lateral AHI were compared in 45 MSA-SDB patients with at least 30min of data in both the supine and lateral positions. When MSA-SDB patients moved from the supine to the lateral position, no significant differences were found in the CAI, MAI. However, the AHI, OAI, HI markedly and significantly decreased (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05). A similar pattern was noted in the MSA-P and MSA-C subgroups. In addition, among the 45 MSA-SDB patients, 64.4% (29/45) were positional sleep apnea.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison of the sleep breathing parameters between the supine and lateral positions in MSA patients with SDB\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003eMSA-SDB\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\" morerows=\"1\" rowspan=\"2\"\u003e\u0026nbsp;\u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;45)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSupine\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eLateral\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e Value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAHI\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e21 (14.1, 29.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e9.4 (4.8, 15.3)\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 \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOAI\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1 (0.3, 5.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0 (0, 0.7)\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 \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCAI\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0 (0, 0.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0 (0, 0.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.103\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMAI\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0 (0, 0.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0 (0, 0.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.156\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHI\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e17.5 (10.8, 23.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e8.1 (3.8, 12.7)\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 \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"4\"\u003eData are presented as the median (Q1, Q3)\u003c/td\u003e\u003c/tr\u003e \u003ctr\u003e\u003ctd colspan=\"4\"\u003e\u003cem\u003eAHI\u003c/em\u003e, Apnea\u0026ndash;hypopnea index; \u003cem\u003eCAI\u003c/em\u003e, Central apnea index; \u003cem\u003eHI\u003c/em\u003e, Hypopnea index; \u003cem\u003eMSA\u003c/em\u003e, Multiple system atrophy; \u003cem\u003eOAI\u003c/em\u003e, Obstructive apnea index; \u003cem\u003eSDB\u003c/em\u003e, Sleep-disordered breathing\u003c/td\u003e\u003c/tr\u003e \u003ctr\u003e\u003ctd colspan=\"4\"\u003e*p\u0026thinsp;\u0026lt;\u0026thinsp;0.05\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe present study demonstrated for the first time that most MSA patients are bound to supine body position. Sleeping in the supine body position is associated with more severe motor symptoms and deterioration in AHI in MSA patients with SDB.\u003c/p\u003e \u003cp\u003eThe overall prevalence of SDB (AHI\u0026thinsp;\u0026gt;\u0026thinsp;5/h) was 84.6%, 83.9%, 85.7% in patients with MSA, MSA-P, and MSA-C, respectively. The prevalence in this study is higher compared to previous report that SDB was reported in 15.4% of 39 Italian MSA patients using AHI\u0026thinsp;\u0026gt;\u0026thinsp;5/h as the diagnostic threshold [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e], and higher than that in 36.8% of 19 MSA patients in 2004 using ODI\u0026thinsp;\u0026gt;\u0026thinsp;10 as the diagnostic threshold [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. The high prevalence of SDB recorded in our sample might be attributable to the increased sensitivity of current recording techniques and scoring criteria. Similar proportions (80% and 85%) were found in 15 and 34 MSA patients in 2010 and in 2022, respectively [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e], using AHI\u0026thinsp;\u0026ge;\u0026thinsp;5/h.\u003c/p\u003e \u003cp\u003eIn this study, the prevalence of SDB in male patients was found higher than that in female patients. After adjusting for sex and age, higher BMI was an independent predictor of SDB in MSA, consistent with previous findings in the general population [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e], these results suggest that high BMI and being male are associated with the presence of SDB in MSA. Previous studies have yielded conflicting results regarding the relationship between BMI and MSA-SDB. While a small-sample study did not find significant differences in BMI between MSA-SDB and MSA-nSDB patients, it did indicate an overall upward trend in BMI among patients with MSA-SDB [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. Additionally, a separate investigation reported a high BMI in MSA patients with obstructive sleep apnea syndrome (OSAS), with an average BMI of 25.9 beyond the normal range [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Moreover, a decrease in BMI has been linked to spontaneous improvement of sleep-disordered breathing in MSA patients [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eOur findings highlight that MSA patients tend to spend approximately 80% of their sleep time in supine position, and increased supine sleep is associated with higher UMSARS-II score, indicating impaired nocturnal mobility. The results align with previous PSG studies demonstrated that up to two thirds of acute stroke patients spend nearly their entire first nights in supine position, while the extent of supine sleep tends to decrease following recovery [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. In addition, Parkinson's disease (PD) patients have been found to slept twice as much in supine position compared to control subjects, and longer PD disease duration was an independent predictor of more supine sleep [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. PD patients with severe obstructive sleep apnea syndrome spent the majority of their sleep time in the supine position (93%) [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eConsistent with prior research on patients with OSA that supine position increased frequency and duration of apneic events [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e], our findings revealed a significant increase in the frequency of obstructive respiratory events when transitioning from the lateral to the supine position among MSA-SDB patients. OSA is characterized by recurrent of the upper airway obstruction during sleep, with the most severe and frequent events observed in the supine sleeping position. The identified mechanism including unfavorable airway geometry, reduced lung volume, and an inability of airway dilator muscles to adequately compensate as the airway collapses, arousal threshold and ventilatory control instability [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. The similar impact pattern of supine body position suggests a common pathogenesis of supine upper airway obstruction in both MSA and the general population.\u003c/p\u003e \u003cp\u003eWe did not observe significant postural effects on the central and mixed respiratory events. which contrasts with the findings of a previous study that demonstrated the attenuation of central sleep apnea severity in patients with heart failure when in the lateral position [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. Central sleep apnea is commonly recognized as a prominent feature in MSA, but it typically manifests in the later stages of the disease due to destruction of medullary chemoreceptors [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e], or it may arise after elimination of upper airway obstruction through CPAP. Given that most MSA patients in our study were in early stages and primarily exhibited untreated obstructive respiratory events, the data on central events were limited, which may restrict the statistical power to evaluate the impact of supine body position on central sleep apnea.\u003c/p\u003e \u003cp\u003eContinuous positive airway pressure (CPAP) and tracheotomy are the established treatments for alleviating obstructive sleep apneas in MSA [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. CPAP is a non-invasive method that works by delivering a constant flow of air through a mask to maintain open airways during sleep, it can reduce the risk of infections and other complications associated with surgical interventions. However, its efficacy is highly dependent on patient compliance. The long-term acceptance of CPAP in MSA patients was poor, up to 66% MSA patients discontinued CPAP treatment with median treatment duration of 13.0 months [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e, \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]. This reduced adherence to CPAP may be attributed to motor impairment and the frequently observed floppy epiglottis. In such cases, CPAP can potentially exacerbate upper airway obstruction and pose a risk of suffocation [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. Tracheostomy can also exacerbate central apneas in MSA, potentially caused by hyperventilation-induced hypocapnia [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]. Positional therapy (the avoidance of the supine position during sleep) has been proposed as a therapeutic strategy in OSA patients from the general population with positional sleep apnea [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e], it might be considered as an alternative option to CPAP in MSA patients especially those failure to adhere CPAP treatment albeit may not a radical solution. Given that excessive supine recumbency seem to be consequence of motor impairment, effective management of nocturnal immobility through physical or pharmacological interventions becomes crucial for optimizing the management of SDB in MSA.\u003c/p\u003e \u003cp\u003eThis study has several limitations. First, as this is an observational study, we cannot prove the benefit of lateral body position on SDB in MSA. Interpreting the effect of positional therapy requires further research. Second, we cannot explain the pathophysiologic traits in supine body position in MSA patients. Third, we lacked a control group for comparing the supine body position percentage. Fourth, most patient were in early stage and presented with relatively low number of central apneas, limited the statistical power to fully evaluate the impact of supine body position on central sleep apnea, postural effect worth further investigation in MSA-CSA patients.\u003c/p\u003e \u003cp\u003eIn conclusion, an increased supine sleep position in people with MSA seems to be an important factor associated with SDB. Our study emphasizes the need for treatment strategies at night to implementing nighttime treatment strategies to reduce excessive supine recumbency in MSA patients, which may ultimately lead to improvements in SDB management in this population.\u003c/p\u003e"},{"header":"Declarations","content":" \u003cp\u003e \u003cstrong\u003eConflicts of interest\u003c/strong\u003e \u003cp\u003eNone of the authors have any conflicts of interest to declare.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eFunding\u003c/h2\u003e \u003cp\u003eThis work was funded by Department of Science and Technology of Sichuan (2023YFS0268 to YMX).\u003c/p\u003e\u003ch2\u003eAuthor contributions\u003c/h2\u003e \u003cp\u003eFX, HW and YMX conceived the idea of the study; HW and FX analyzed the data; HYH, YQS, YB, DZ, HW contributed data acquisition; JYZ interpreted the results; FX and HW wrote the paper; all authors discussed the results and revised the manuscript.\u003c/p\u003e\u003ch2\u003eAcknowledgements\u003c/h2\u003e \u003cp\u003eWe would like to thank the study participants and the staff of the Sleep Medicine Center of West China Hospital.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eStefanova N, B\u0026uuml;cke P, Duerr S, Wenning GK (2009) Multiple system atrophy: an update. Lancet Neurol 8:1172\u0026ndash;1178\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGilman S, Chervin RD, Koeppe RA et al (2003) Obstructive sleep apnea is related to a thalamic cholinergic deficit in MSA. Neurology 61:35\u0026ndash;39\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eIranzo A (2005) Management of sleep-disordered breathing in multiple system atrophy. Sleep Med 6:297\u0026ndash;300\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJo S, Kim TY, Lee YS et al (2024) Severity of sleep apnea as a prognostic factor for mortality in patients with multiple system atrophy. Parkinsonism Relat Disord 124:106994\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCortelli P, Calandra-Buonaura G, Benarroch EE et al (2019) Stridor in multiple system atrophy: Consensus statement on diagnosis, prognosis, and treatment. 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Neurology 68:1618\u0026ndash;1621\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":"clinical-autonomic-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"autr","sideBox":"Learn more about [Clinical Autonomic Research](http://link.springer.com/journal/10286)","snPcode":"10286","submissionUrl":"https://www.editorialmanager.com/autr/default2.aspx","title":"Clinical Autonomic Research","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Multiple system atrophy, Sleep-disordered breathing, Sleep position, Supine","lastPublishedDoi":"10.21203/rs.3.rs-4753121/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4753121/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003ePurpose\u003c/h2\u003e \u003cp\u003eSleep-disordered breathing (SDB) is prevalent in multiple system atrophy (MSA) patients. Clinical observations suggest a predominance of supine sleep due to disabled mobility. This study aimed to assess the effect of supine position on SDB in MSA patients.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eThis cross-sectional study enrolled 104 \"probable\" MSA patients. Patients with apnea-hypopnea index (AHI)\u0026thinsp;\u0026gt;\u0026thinsp;5/h were diagnosed with SDB. AHI in supine and lateral positions were compared. Association between supine sleep percentage and AHI was assessed using generalized linear model.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eThe frequency of SDB was 84.6% (88/104) in MSA. Up to 51.9% (54/104) MSA patients spend more than 80% sleep time on supine position. Unified Multiple System Atrophy Rating Scale part II scores positively correlated with supine sleep percentage (r\u0026thinsp;=\u0026thinsp;0.229, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.019). After adjusting for age, sex, BMI, and UMSARS-II score, more supine position percentage predict higher AHI (β coefficient 0.122, 95% confidence interval 0.002\u0026ndash;0.241). Among the 45 MSA-SDB patients with at least 30 minutes of data in both supine and lateral positions, 64.4% (29/45) exhibited positional sleep apnea (\u0026gt;\u0026thinsp;50% reduction in the AHI between the supine and the lateral position). The supine AHI was significantly higher than lateral AHI in MSA-SDB patients (21.0 [14.1, 29.6] /h vs. 9.4 [4.8, 15.3] /h, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001).\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eSupine sleep position is common in MSA and increases with more severe motor symptoms. Sleeping in supine position exacerbates respiratory events. Management of motor symptoms may help reduce supine position and improve SDB in MSA patients.\u003c/p\u003e","manuscriptTitle":"Impact of supine body position on sleep-disordered breathing in MSA patients","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-09-09 18:33:11","doi":"10.21203/rs.3.rs-4753121/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"","date":"2024-08-04T16:54:33+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-08-03T18:02:03+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-07-18T14:14:55+00:00","index":"","fulltext":""},{"type":"submitted","content":"Clinical Autonomic Research","date":"2024-07-17T05:15:34+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"clinical-autonomic-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"autr","sideBox":"Learn more about [Clinical Autonomic Research](http://link.springer.com/journal/10286)","snPcode":"10286","submissionUrl":"https://www.editorialmanager.com/autr/default2.aspx","title":"Clinical Autonomic Research","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"5ffcc5c1-850f-41d4-b64a-cce6df978112","owner":[],"postedDate":"September 9th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2024-12-16T16:06:47+00:00","versionOfRecord":{"articleIdentity":"rs-4753121","link":"https://doi.org/10.1007/s10286-024-01099-0","journal":{"identity":"clinical-autonomic-research","isVorOnly":false,"title":"Clinical Autonomic Research"},"publishedOn":"2024-12-10 15:57:53","publishedOnDateReadable":"December 10th, 2024"},"versionCreatedAt":"2024-09-09 18:33:11","video":"","vorDoi":"10.1007/s10286-024-01099-0","vorDoiUrl":"https://doi.org/10.1007/s10286-024-01099-0","workflowStages":[]},"version":"v1","identity":"rs-4753121","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4753121","identity":"rs-4753121","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}