Masked Hypertension: A Systematic Review

Masked phenomenon, Masked Hypertension (MHT) and Masked Uncontrolled Hypertension (MUCH) is a well-defined clinical entity. However, many aspects of MHT/MUCH remain unclear.

We systematically reviewed the published literature on MHT/MUCH from 1 January 2000 to 31 June 2018 with a particular focus on epidemiology, clinical significance, evaluation and management. Meta-analyses were performed with respect to prevalence, clinical significance and diagnostic agreement between home blood pressure (HBP) and ambulatory BP (ABP) measurements.

The overall weighted-mean prevalence of masked phenomenon was 11% [9,14]; MHT 10% [9,11]; and MUCH 13% [8,17]. The weighted-mean prevalence when expressed as a proportion of patients with normal office BP was 32% [25,40]; MHT 28% [15,41]; and MUCH 43% [29,57]. The prevalence of masked phenomenon determined by ABP (11% [8,14]) and HBP (13% [9,16]), was similar. However, ABP appeared to have a greater sensitivity, i.e. proportion of patients diagnosed as having MHT/MUCH was greater with ABP than with HBP (22% v 16%, p<0.05), when both methodologies were applied to the same cohort of patients. The prevalence of MHT was influenced by ethnicities and comorbidities, and in case of MUCH by anti-hypertensive treatment. MHT/MUCH was associated with increased risk of fatal and non-fatal cardiac/cerebrovascular events (relative risk [RR] 2.09 [1.80, 2.44]), and the risk was comparable to sustained hypertension (SHT) (RR 2.26 [1.84, 2.78]). The increased risk occurred regardless of the method of out of office BP assessment; the relative risks for ABP and HBP were 2.38 [1.90, 2.98] and 1.90 [1.57, 2.29] respectively. The diagnostic agreement between ABP and HBP was only modest, kappa = 0.46 [0.40, 0.52], even though the percentage agreement was 83%. The evidence for the management of MHT was scant.

MHT/MUCH is a common BP phenotype with a risk profile similar to that of SHT. Therefore, high risk patients should undergo out of office BP assessment, probably both by HBP and ABP, to confirm diagnosis and be considered for treatment.