Elsevier

Sleep Medicine

Volume 26, October 2016, Pages 46-53
Sleep Medicine

Original Article
Racial/ethnic differences in the associations between obesity measures and severity of sleep-disordered breathing: the Multi-Ethnic Study of Atherosclerosis

https://doi.org/10.1016/j.sleep.2015.06.003Get rights and content

Highlights

  • We studied associations of obesity measures with sleep apnea severity in US adults.

  • Body mass index and waist circumference were related to apnea–hypopnea index in all racial/ethnic groups.

  • These associations were stronger in Chinese than in Whites, Blacks, and Hispanics.

  • Associations were not explained by sociodemographics, comorbidities, or lifestyles.

Abstract

Objectives

The objective of this study was to evaluate associations between obesity measures and sleep-disordered breathing severity among White, Black, Hispanic, and Chinese Americans.

Methods

The method used in this study was a community-based cross-sectional study of 2053 racially/ethnically diverse adults in the Multi-Ethnic Study of Atherosclerosis. Anthropometry and polysomnography were used to measure obesity and apnea–hypopnea index (AHI). Linear regression models were fitted to investigate associations of body mass index (BMI) and waist circumference with AHI (log transformed) with adjustment for sociodemographics, lifestyle factors, and comorbidities.

Results

The mean participant age was 68.4 (range: 54–93) years; 53.6% of participants were women. The median AHI was 9.1 events/h. There were significant associations of BMI and waist circumference with AHI in the overall cohort and within each racial/ethnic group. A significant interaction was observed between race/ethnicity and BMI (Pinteraction = 0.017). Models predicted that for each unit increase in BMI (kg/m2), the mean AHI increased by 19.7% for Chinese, 11.6% for Whites and Blacks, and 10.5% for Hispanics. Similarly, incremental changes in waist circumference were associated with larger increases in AHI among Chinese than among other groups.

Conclusions

Associations of BMI and waist circumference with AHI were stronger among Chinese than among other racial/ethnic groups. These findings highlight a potential emergence of elevated sleep-disordered breathing prevalence occurring in association with increasing obesity in Asian populations.

Introduction

The burdens of obesity and sleep-disordered breathing (SDB) are disproportionately borne by racial/ethnic minorities in the United States [1], [2]. Both obesity and SDB are associated with hypertension, diabetes, cardiovascular disease (CVD), and mortality [3], [4], [5], [6], [7], [8]. Previous studies have shown some variations in the prevalence and severity of SDB by race/ethnicity [9], [10], [11]. For example, in a cross-sectional study of 308 obese patients with body mass index (BMI) of ≥35 kg/m2, South Asians had a significantly higher prevalence and more severe SDB than White Europeans [11]. Our recent findings in the Multi-Ethnic Study of Atherosclerosis (MESA) indicate that SDB is prevalent among middle-aged and older US adults, and that Hispanics and Chinese have higher odds of SDB than Whites after considering the influence of BMI [12]. Although SDB appears to vary by race/ethnicity, the basis for this variation is unclear.

Obesity is a strong risk factor for SDB. Although the association between obesity and SDB has been well established in theliterature, less is known regarding whether the strength of this association varies across racial/ethnic groups. Sands-Lincoln and colleagues showed that the relationship between sleep apnea and hypertension depended on race/ethnicity and obesity [8]. There may be a complex association among SDB, race/ethnicity, and obesity. Furthermore, other risk factors for SDB, such as craniofacial structure, upper airway collapsibility, and ventilatory control, may also vary across population groups [13]. As BMI and body fat distribution vary by race/ethnicity [14], it is important to understand whether group differences in SDB are related to differences in levels of BMI or to differences in central obesity (as measured by waist circumference), or to propensity for SDB with incremental increases in body weight. This information may help identify risk factors that confer increased SDB within racial/ethnic groups, and it may also help develop targeted intervention strategies.

This study aimed to better understand how variation in body weight and body fat distribution was associated with SDB severity within racial/ethnic groups after adjustment for possible confounders, including sociodemographic factors, physical activity, smoking status, and comorbidities. We also sought to explore potential variation in these associations by age and sex. We systematically evaluated the associations between general (BMI) and abdominal obesity (waist circumference) measures with polysomnography (PSG)-measured SDB severity across four racial/ethnic groups (White, Black, Hispanic, and Chinese Americans). Waist circumference has been considered a simple and valuable anthropometric measure of abdominal obesity [15]. As age and sex are related to obesity and SDB severity [1], [6], we conducted exploratory analyses to examine the potential three-way interactions of age, sex, and race/ethnicity with BMI and waist circumference pertaining to SDB severity.

Section snippets

Study design and participants

MESA is a multisite prospective study designed to investigate the prevalence and progression of subclinical CVD, and to identify risk factors for incident CVD in a racially/ethnically diverse sample. The description of the study design for MESA has been published [16]. Briefly, between 2000 and 2002, a total of 6814 men and women who identified themselves as White, Black/African-American, Hispanic, or Chinese aged 45–84 years and free of clinically apparent CVD were recruited from six US

Participant characteristics

Table 1 displays sociodemographic and clinical characteristics of study participants by race/ethnicity. Participants were on average of 68.4 [standard deviation (SD): 9.1]; range: 54–93 years old; 53.6% of participants were female. The mean BMI was lowest for Chinese (mean = 24.2; SD = 3.3), followed by Whites (mean = 28.0; SD = 5.2), Hispanics (mean = 30.0; SD = 5.5), and Blacks (mean = 30.3; SD = 5.6). The mean waist circumference was also lowest for Chinese, followed by Whites, Hispanics,

Discussion

A comparison of the prevalence and risk factors for SDB across racial/ethnic groups can be helpful for identifying social, environmental, and genetic factors that may contribute to SDB. However, to date, few studies have explored the complex associations among race/ethnicity, obesity measures, and SDB severity in direct interethnic comparisons. Given the availability of rigorously collected PSG data as well as anthropometric measures in a relatively large multiethnic cohort, we were able to

Conflict of interest

All authors have no conflict of interest in relation to the work described.

The ICMJE Uniform Disclosure Form for Potential Conflicts of Interest associated with this article can be viewed by clicking on the following link: http://dx.doi.org/10.1016/j.sleep.2015.06.003.

. ICMJE Form for Disclosure of Potential Conflicts of Interest form.

Acknowledgments

The Multi-Ethnic Study of Atherosclerosis (MESA) is supported by contracts N01-HC-95159 through N01-HC-95169 from the National Heart, Lung, and Blood Institute (NHLBI) at the National Institutes of Health. The work presented in this paper was supported by grants from NIH 1R01HL083075-01, R01HL098433, R01 HL098433-02S1, 1U34HL105277-01, 1R01HL110068-01A1 1R01HL113338-01, R21 HL108226, P20 NS076965, 3R01HL115941-01S1, UL1TR001102, 5T32HL007901, and R01 HL109493. This work was also supported by an

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