High Prevalence Of Sleep-disordered Breathing In Chinese Patients With Difficult-to-control Hypertension

Abstract

Aim: To evaluate the prevalence of sleep disordered breathing (SDB) in Chinese subjects with difficult-to-control hypertension. Methods: Medical records of patients attending the hypertension clinic at a university teaching hospital were screened over 2 years. Inclusion criteria were age 18 to 65 years with hypertension requiring three or more anti-hypertensive medications. Patients with known secondary causes of hypertension, unstable medical illnesses in the past 3 months, on drugs (other than anti-hypertensives) that might influence blood pressure were excluded. Eligible subjects were invited to undergo 24-hour ambulatory blood pressure measurement and polysomnography (PSG). Results: A total of 124 subjects were interviewed and 101 consented for the study. Two are awaiting PSG, six had defaulted the appointment and 93 underwent PSG, with the mean age of 51.6±8.5 years, male:female=1.7:1, mean body mass index (BMI) 29.7±5.2 kg/m2, mean systolic blood pressure 140.9±16.1 mm Hg, mean diastolic blood pressure 81.8±10.2 mm Hg. Of the 93 subjects who completed the study, SDB (apnoea hypopnoea index AHI >5/ hour) was diagnosed in 71 subjects (76.3%) [mean age 51.6±8.9 years, male:female=2.5:1, mean BMI 30.7±4.9 kg/ m2]. Fifty-three (53/93=57%) had moderate or severe SDB (AHI ≥15/hour). Among those with SDB, obstructive apnoea was the predominant type of SDB seen. Central apnoea predominance was observed in two subjects (2.6%). Conclusion: SDB, in particular obstructive sleep apnoea, was found to be highly prevalent in Chinese with difficult-tocontrol hypertension, and high awareness of this association is warranted.