Author + information
- Eleanor L. McGlinchey, PhD∗ (, )
- Linda Oyesiku, MPH,
- Keith M. Diaz, PhD,
- Siqin Ye, MD, MS,
- Marwah Abdalla, MD, MPH,
- Joseph E. Schwartz, PhD,
- Karina W. Davidson, PhD and
- Carmela Alcántara, PhD
- ↵∗New York State Psychiatric Institute, Columbia University Medical Center, 1051 Riverside Drive, Unit 78, New York, New York 10032
Short duration of sleep, defined as sleeping ≤7 h per night, is associated with poor cardiovascular disease (CVD) outcomes, including mortality (1,2). There are known racial disparities for CVD (3) and for sleep health (4). However, racial disparities in the context of short sleep with CVD is an understudied area (2,5). The current study examined whether black race modifies the association of sleep duration with recurrent CVD risk in patients with a history of acute coronary syndrome (ACS).
A total of 722 patients admitted for ACS (defined as ST-segment elevation myocardial infarction [MI], non-ST-segment elevation MI, or unstable angina) who identified as black (n = 175 subjects) or white (n = 547 subjects) were enrolled in-hospital and followed for 1 year in a single-site, prospective observational cohort from 2009 through 2012. Columbia University Medical Center’s institutional review board approved this study.
One month after enrollment, participants completed the Pittsburgh Sleep Quality Index. Sleep duration was categorized as short (<7 h/night) versus average (≥7 h/night), following previous guidelines (1,2). Major adverse cardiovascular events (MACE) were defined as the composite of death, recurrent MI, or unstable angina.
Hazard ratios (HR) and 95% confidence intervals (CI) for MACE were estimated from a Cox regression model that included sleep duration and race as the primary predictors, their interaction term, with age, sex, GRACE (Global Registry of Acute Coronary Events) risk score, and Charlson comorbidity index included as covariates, after a preliminary forward selection analysis that considered 20 potential predictors of MACE excluding sleep duration.
At 1-year follow-up, there were 62 recurrent MACE. As previously reported, short duration of sleep was associated with increased risk of recurrent MACE (1). Black race was associated with increased risk of recurrent MACE compared with white race in unadjusted and multivariate adjusted models (adjusted HR: 2.14; 95% CI: 1.26 to 3.63; p = 0.005). Sleep duration was not associated with race in the current sample (p = 0.30). However, there was a significant interaction between race and sleep duration (p = 0.02) (Figure 1) such that black patients who regularly slept <7 h/night 1 month post-ACS had a higher risk for recurrent MACE than white patients who slept ≥7 h/night (adjusted HR: 2.88; 95% CI: 1.51 to 5.50; p = 0.001), as well as the other 2 race × sleep duration subgroups. The interaction remained significant after excluding snorers (≥1/week snoring based on Pittsburgh Sleep Quality Index responses) and patients with sleep duration >9 h/night.
This study found that the occurrence of MACE was significantly greater among blacks who reported short sleep (<7 h/night) 1 month post-ACS than among whites with short sleep and those who slept 7 h or more per night (both blacks and whites). There was not a significant difference in sleep duration between blacks and whites in the current sample; however, previous work indicates that blacks are more than twice as likely to report short duration of sleep than whites (4,5). A recent review suggests that sleep may be fundamental to understanding some of the racial disparities in cardiovascular risk (5). These data support and extend that hypothesis, showing that race modifies the adverse cardiac prognosis associated with short duration of sleep.
Recent work has begun to delineate possible psychophysiological mechanisms linking short sleep to CVD, including increased allostatic load (2,4) from chronic short sleep contributing to elevated cortisol and inflammation (2). Less is known about the mechanisms linking black race to both CVD and short sleep, although recent proposals have indicated greater exposure to discrimination and neighborhood factors such as noise and reduced safety may be important contributors (2,5).
One limitation of this study is the reliance on self-reported sleep duration. Future work should use multiple measurements of sleep, including objective measurements. Also, participants were drawn from 1 particular hospital setting in an urban metropolitan city, potentially limiting generalizability. Despite these limitations, the current report advances the science of cardiovascular health disparities and suggests that sleep may be a potential modifiable behavioral target for reducing racial health disparities.
Please note: The authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- 2018 American College of Cardiology Foundation
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