ETHNIC DIFFERENCES IN THE PREVALENCE OF MASKED HYPERTENSION PHENOTYPES: ISOLATED AMBULATORY, ISOLATED HOME, AND DUAL MASKED HYPERTENSION

Abstract

Objective: Ethnic differences in the prevalence of masked hypertension (MH) are known. However, no studies have examined whether there are ethnic differences in the prevalence of MH phenotypes, assessed by ambulatory blood pressure (ABP) or home blood pressure (HBP), or both. The object was to investigate the ethnic differences in the prevalence of MH phenotype in individuals without a previous diagnosis of hypertension (NHT) and those with a diagnosed hypertension (HT). Design and method: Cross-sectional ABP, HBP, office blood pressure (OBP) and characteristic data were compared in 1,588 participants (mean age 61.8±10.4 years, 49.2% males, 80.1% HT, White British 16.8%, South Asian 9.9%, African Caribbean 10.6%, Japanese 62.7%) from combined database of the UK and Japan in clinical practice. Isolated ambulatory MH was defined as normal OBP (<140/90 mmHg) and HBP (<135/85 mmHg) and elevated daytime ABP (> = 135/85 mmHg), isolated home MH as normal OBP and daytime ABP (<135/85 mmHg) and elevated HBP (> = 135/85 mmHg), and dual MH as normal OBP and elevated daytime ABP and HBP. Results: Among participants with any phenotype of MH in NHT (n = 129) or HT (n = 356), 31.0% and 36.0% had isolated ambulatory MH, 29.5% and 25.3% isolated home MH, and 39.5% and 38.7% dual MH, respectively. For the diagnostic accuracy of HBP against daytime ABP for MH, there were no differences among groups in NHT; low sensitivity (50-73%), but moderate specificity (74-88). In HT, Japanese showed lower sensitivity (38%) than others (72-79%). There were no differences in specificities (78-94%) among groups. In diagnostic agreements of MH between ABP and HBP monitoring, Japanese showed lower reproducibility both in NHT and HT (Kappa statistic, 0.28 and 0.38, respectively) than other groups (0.38-0.52 and 0.51-0.55). In multivariate logistic regression analysis, Japanese in NHT showed higher odds ratio (OR) for isolated ambulatory MH and those in HT showed lower OR for isolated home MH compared with White British: 4.01 (p = 0.016), 0.36 (p = 0.004), respectively. Conclusions: In Japanese population compared with White British, HBP alone might underestimate the prevalence of MH and ABP could behave as a complementary to HBP.