Millions of Adults May Have Masked Hypertension

Millions of US adults may be misclassified as not having hypertension, according to a new study. The researchers call this the first estimate of the US prevalence of masked hypertension (MHT).

“The reason masked hypertension is significant is that it is associated with increased cardiovascular risk and it cannot be diagnosed solely in the clinic setting; it can only be diagnosed if out-of-clinic blood pressure is also assessed—preferably 24-hour ambulatory blood pressure (ABP) monitoring, but alternatively home blood pressure monitoring,” said study author Joseph E. Schwartz, PhD, professor of psychiatry and sociology at Stony Brook University in Stony Brook, New York. “On the other hand, while there is a prima facie case for treating masked hypertension—with medication and/or lifestyle changes—no randomized controlled study has yet been conducted to evaluate the benefit of treating this condition.”
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After pooling data from the Masked Hypertension Study (n=811), a cross-sectional clinical investigation of systematic differences between clinic BP and ABP in a community sample of employed adults in the New York City metropolitan area (2005-2012), and the National Health and Nutrition Examination Survey (NHANES; 2005-2010; n=9316), an ongoing nationally representative US survey, the researchers used multiple imputation to impute ABP-defined hypertension status for NHANES participants and estimate MHT prevalence among the 139 million US adults with nonelevated clinic BP, no history of overt cardiovascular disease, and no use of antihypertensive medication.

The estimated US prevalence of MHT in 2005-2010 was 12.3% of the adult population (95% CI: 10.0, 14.5)—approximately 17.1 million people aged 21 years or older. Consistent with prior research, they found estimated MHT prevalence higher among older people, men, and people with prehypertension or diabetes.

“We have a very rich dataset from the Masked Hypertension Study on which we continue to conduct analyses and publish,” Dr Schwartz said. “In addition, approximately 50% of the sample repeated the study an average of 7 years after their initial participation. This follow-up evaluation has just been completed, and analyses are about to begin.”

Looking to the future, they plan to submit an application requesting National Institutes of Health funding to evaluate the feasibility of conducting a randomized clinical trial of the benefit of treating patients with MHT with a low-dose antihypertensive.

—Mike Bederka

Reference:

Wang YC, Shimbo D, Muntner P, Moran AE, Krakoff LR, Schwartz JE. Prevalence of masked hypertension among US adults with nonelevated clinic blood pressure [published online January 18, 2017]. Am J Epidemiol. doi:https://doi.org/10.1093/aje/kww237