To determine the prevalence of obstructive sleep apnoea
(OSA) in adult patients with drug-resistant hypertension
, a common problem in a tertiary care facility.
Patients and methods
Adults with drug-resistant hypertension
, defined as a clinic blood pressure
140/90 mmHg, while taking a sensible combination of three or more antihypertensive drugs, titrated to maximally recommended doses. Each of the 41 participants completed an overnight polysomnographic study and all but two had a 24 h ambulatory blood pressure measurement
Prevalence of OSA, defined as an apnoea-hypopnoea index of ≥
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 index, 34.0 ±
) and taking a mean of 3.6 ±
0.1 different antihypertensive 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 32.2 ±
4.5 versus 14.0 ±
3.1 events/h, P
= 0.004). There was no gender difference in body mass index or age. Women with OSA were significantly older and had a higher systolic blood pressure
, lower diastolic blood pressure
, wider pulse pressure and slower heart rate than women without OSA.
The extraordinarily high prevalence of OSA in these patients supports its potential role in the pathogenesis of drug-resistant hypertension
, and justifies the undertaking of a randomized controlled trial to corroborate this hypothesis.