High prevalence of unrecognized sleep apnoea in drug-resistant hypertension

Objectives To determine the prevalence of obstructive sleep apnoea (OSA) in adult patients with drug-resistant hypertension, a common problem in a ter tiary care facility. Design Cross-sectional study. Setting University hypertension clinic. Patients and methods Adults with drug-resistant hypertension, defined as a clinic blood pressure of greater than or equal to 140/90 mmHg, while taking a sensible combination of three or more antihypertensive drugs, titrated t o maximally recommended doses. Each of the 41 participants completed an ove rnight polysomnographic study and all but two had a 24 h ambulatory blood p ressure measurement Results Prevalence of OSA, defined as an apnoea-hypopnoea index of greater than or equal to 10 obstructive events per hour of sleep, was 83% in the 24 men and 17 women studied. Patients were generally late middle-aged (57.2 /- 1.6 years, mean +/- SE), predominantly white (85%), obese (body mass ind ex, 34.0 +/- 0.9 kg/m(2)) and taking a mean of 3.6 +/- 0.1 different antihy pertensive medications daily. OSA was more prevalent in men than in women ( 96 versus 65%, P = 0.014) and more severe (mean apnoea-hypopnoea index of 3 2.2 +/- 4.5 versus 14.0 +/- 3.1 events/h, P = 0.004). There was no gender d ifference in body mass index or age. Women with OSA were significantly olde r and had a higher systolic blood pressure, lower diastolic blood pressure, wider pulse pressure and slower heart rate than women without OSA. Conclusions The extraordinarily high prevalence of OSA in these patients su pports its potential role in the pathogenesis of drug-resistant hypertensio n, and justifies the undertaking of a randomized controlled trial to corrob orate this hypothesis. J Hypertens 19:2271-2277 (C) 2001 Lippincott William s & Wilkins.