Objectives: Apnea hypopnea index (AHI) is used to study the association between obstructive sleep apnea (OSA) and hypertension, but the independent contributions of total sleep time (TST) and apnea/hypopnea event count to hypertension have not been previously investigated. We studied the relationship between polysomnographically assessed TST and hypertension in a sex-balanced community-dwelling cohort of hypertensive patients and normotensive controls (Skara Sleep Cohort).
Methods: Participants (n = 344, men 173, age 61.2 ± 6.5 years, BMI 28.6 ± 4.8 kg/m2, mean ± SD) underwent ambulatory home polysomnography. Hypertension was defined according to contemporary Swedish national guidelines. A multivariate logistic regression model was used to predict hypertension status from TST and apnea/hypopnea count (total events/night) adjusting for sex, age and BMI.
Results: OSA was highly prevalent in this population (AHI 26 ± 24 events/h). Hypertensive patients had shorter TST than normotensive patients (353 ± 81 vs. 389 ± 65 min, P < 0.001), whereas total apnea/hypopnea count did not differ (167 ± 138 vs. 146 ± 148 events/night, P = 0.2). Multivariate logistic regression analysis revealed that short TST was associated with hypertension status [odds ratio 2.0; 95% confidence interval (95% CI) 1.2–3.3; P = 0.0015]. The significant association between apnea/hypopnea count and hypertension status was nonlinear (odds ratio 2.6; 95% CI 1.2–5.8; P = 0.04). The type of antihypertensive treatment was not found to significantly influence TST.
Conclusion: Short sleep time assessed by polysomnography was associated with hypertension in this community-dwelling population. Short sleep and presence of sleep apnea appear to independently link to hypertension.
aCenter for Sleep and Wake Disorders, Institute of Medicine, University of Gothenburg, Gothenburg
bR&D Centre Skaraborg Primary Care
cSkaraborg Institute, Skövde, Sweden
Correspondence to Ding Zou, MD, PhD, Center for Sleep and Wake Disorders, University of Gothenburg, Box 421, SE 405 30 Gothenburg, Sweden. Tel: +46 31 3423599; fax: +46 31 825207; e-mail: firstname.lastname@example.org
Abbreviations: AHI, apnea/hypopnea index; BP, blood pressure; OSA, obstructive sleep apnea; PSG, polysomnography; TST, total sleep time
Received 28 June, 2012
Revised 18 September, 2012
Accepted 26 October, 2012