Repetitive arousals from sleep are independently associated with prevalent hypertension in patients with obstructive sleep apnea (OSA), according to a study published in Journal of the American Heart Association.
In this cross-sectional study, researchers obtained data on the health status, comorbidities, medical therapies, and history of sleep complaints in patients with clinical suspicion of OSA (N=11,716). Patients with an apnea-hypopnea index (AHI) greater than or equal to 5 were classified as patients with OSA, and those with an AHI of less than 5 events per hour were included in the primary snoring group. AHI was defined as the total number of apneas and hypopneas for each hour of sleep. Hypopneas were measured as being less than or equal to 50% reduction in airflow for greater than or equal to 10 seconds and associated with a greater than or equal to 3% decrease in oxygen desaturation or an arousal. Arousals were defined as rapid shifts in electroencephalographic frequency. Researchers measured blood pressure (BP) at 2 time points (approximately 2 hours before polysomnography recorded in the evening and following completion of a sleep study the next morning. Hypertension was defined as systolic BP greater than or equal to 140 mm Hg or diastolic BP greater than or equal to 90 mm Hg.
The odds of hypertension were significantly higher in patients with greater total arousal index (AI) and respiratory AI (odds ratio [OR] for every 10-unit increase in total AI (1.08; 95% CI, 1.03-1.14; P= .002). For every 10-unit increase in respiratory AI, the OR was 1.13 (95% CI, 1.07-1.19; P <.001) and in the OSA group (total AI: OR, 1.10; 95% CI, 1.04-1.16; P <.001; respiratory AI: OR, 1.16; 95% CI, 1.07-1.20; P <.001). After adjusting for confounding variables, both the total AI and respiratory AI were significantly associated with systolic BP and diastolic BP values in the total sample (for total AI: β=0.05 and β=0.06; P <.001; respiratory AI: β=0.06 and β=0.10; P <.001) and in the OSA group (total AI: β=0.05 and β=0.06; P <.001; respiratory AI: β=0.06 and β=0.09; P <.001). Accordingly, researchers noted that significant findings were not observed in the primary snoring patients.
“Combinations of respiratory events and arousals may actually be more detrimental for hypertension risk,” the researchers wrote. “Further studies with longitudinal designs are warranted to delineate the temporal association between repetitive arousals and hypertension, and to determine whether interventions to reduce repetitive arousals may also contribute to lower BP in patients with OSA.”
Ren R, Zhang Y, Yang L, Somers VK, Covassin N, Tang X. Association between arousals during sleep and hypertension among patients with obstructive sleep apnea. J Am Heart Assoc. Published online December 31, 2021. doi: 10.1161/JAHA.121.022141