Prevalence and Determinants of Masked Hypertension in Nigeria: The REMAH Study

Abstract

Background: Estimating the burden of hypertension in Nigeria hitherto relied on clinic blood pressure (BP) measurement alone. This excludes individuals with masked hypertension (MH), i.e., normotensive clinic but hypertensive out-of-clinic BP.

Methods: In a nationally representative sample of adult Nigerians, we obtained clinic BP using auscultatory method and out-of-clinic BP by self-measured home BP with semi-automated oscillometric device. Clinic BP was average of 5 consecutive measurements and home BP was average of 3 days duplicate morning and evening readings. MH was clinic BP <140 mm Hg systolic and 90 mm Hg diastolic and home BP ≥135 mm Hg systolic and/or 85 mm Hg diastolic.

Results: Among 933 participants, the prevalence of sustained hypertension, MH, and white-coat hypertension was 28.3%, 7.9%, and 11.9%, respectively. Among subjects whose clinic BP were in the normotensive range (n = 558), the prevalence of MH was 13%; 12% among untreated and 27% among treated individuals. The mutually adjusted odds ratios of having MH among all participants with normotensive clinic BP were 1.33 (95% confidence interval, 1.10-1.60) for a 10-year higher age, 1.59 (1.09-2.40) for a 10 mm Hg increment in systolic clinic BP, and 1.16 (1.08-1.28) for a 10 mg/dl higher random blood glucose. The corresponding estimates in the untreated population were 1.24 (1.03-1.51), 1.56 (1.04-2.44), and 1.16 (1.08-1.29), respectively.

Conclusions: MH is common in Nigeria and increasing age, clinic systolic BP, and random blood glucose are the risk factors.

Keywords: Nigeria; blood pressure; clinic BP; home BP; hypertension; masked hypertension; white-coat hypertension.