Hypertension prevalence in obstructive sleep apnoea and sex: a population-based case-control study

Obstructive sleep apnoea (OSA) is a recognised risk factor for hypertension (HT). The current authors investigated confounders of this association in a sex-balanced community-based sample of patients with HT (n=161) from the Skaraborg Hypertension and Diabetes Project (n=1,149) and normotensive controls (n=183) from an age and sex stratified community-based population sample (n=1,109). All participants underwent ambulatory home polysomnography. Severe OSA (apnoea-plus-hypopnoea index (AHI)>or=30 events.h-1) was found in 47 and 25% of hypertensive and normotensive males, respectively. The corresponding numbers in females were 26 and 24%, respectively. The odds ratio (OR) for HT increased across AHI tertiles from 1.0 to 2.1 (95% confidence interval: 0.9-4.5) and 1.0 to 3.7 (95% CI: 1.7-8.2) in males, but not in females where the OR increased from 1.0 to 1.8 (95% CI: 0.8-3.9) and 1.0 to 1.6 (95% CI: 0.7-3.5). Regression analysis correcting for age, body mass index (or waist-hip ratio) and smoking did not eliminate the association between OSA and HT in males. The present data suggest that obstructive sleep apnoea is highly prevalent in both the general population and in patients with known hypertension. The contribution of obstructive sleep apnoea to hypertension risk may be sex dependent and higher in males than in females.