Population-Based Study of Sleep-Disordered Breathing as a Risk Factor for Hypertension

TLDR

Clinical observations have linked sleep‑disordered breathing, characterized by repeated apneas and hypopneas during sleep, to hypertension, yet an independent association has not been firmly established. The study aimed to determine whether sleep‑disordered breathing is independently associated with elevated blood pressure, accounting for confounding factors, in a large adult cohort. Overnight polysomnography quantified apnea‑hypopnea index in 1,060 adults aged 30‑60 from the Wisconsin Sleep Cohort, and blood pressure was measured during the same night. Blood pressure increased linearly with apnea‑hypopnea index, with stronger effects in less obese participants; at BMI 30, an index of 15 corresponded to 3.6 mm Hg systolic and 1.8 mm Hg diastolic rises and a 1.8 odds ratio for hypertension, demonstrating a dose‑response that could account for hypertension in many adults.

Abstract

Clinical observations have linked sleep-disordered breathing, a condition of repeated apneas and hypopneas during sleep, with hypertension but evidence for an independent association has been lacking. Understanding this relationship is important because the prevalence of sleep-disordered breathing is high in adults.To test the hypothesis that sleep-disordered breathing is related to elevated blood pressure independent of confounding factors.The sample included 1060 employed women and men aged 30 through 60 years who had completed an overnight protocol as part of the Wisconsin Sleep Cohort Study. In-laboratory polysomnography was used to determine sleep-disordered breathing status, quantified as the number of apneas and hypopneas per hour of sleep (apnea-hypopnea index). Blood pressure was measured on the night polysomnography was performed.Blood pressure increased linearly with increasing apnea-hypopnea index (P = .003 for systolic, P = .01 for diastolic, adjusted for confounding factors). The magnitude of the linear association increased with decreasing obesity. At a body mass index (weight in kilograms divided by the square of the height in meters) of 30 kg/m2, an apnea-hypopnea index of 15 (vs 0) was associated with blood pressure increases of 3.6 mm Hg for systolic (95% confidence interval, 1.3-6.0) and 1.8 mm Hg for diastolic (95% confidence interval, 0.3-3.3). The odds ratio for hypertension associated with an apnea-hypopnea index of 15 (vs 0) was 1.8 (95% confidence interval, 1.3-2.4).There is a dose-response relationship between sleep-disordered breathing and blood pressure, independent of known confounding factors. If causal, the high prevalence of sleep-disordered breathing could account for hypertension in a substantial number of adults in the United States.