Association of Cardiovascular Outcomes With Masked Hypertension Defined by Home Blood Pressure Monitoring in a Japanese General Practice Population

Importance: The clinical outcomes associated with masked hypertension defined by home blood pressure monitoring (HBPM) in clinical settings remain uncertain. Objective: To assess the association between masked hypertension and cardiovascular disease events in clinical settings. Design, Setting, and Participants: This observational cohort study used data from 4261 outpatients treated at 71 primary practices or university hospitals throughout Japan who were enrolled in the Japan Morning Surge-Home Blood Pressure study between January 1, 2005, and December 31, 2012. Participants had a history of or risk factors for cardiovascular disease and were followed up through March 31, 2015. Participants underwent clinic blood pressure (BP) measurements on 2 occasions as well as HBPM measurements in the morning and evening for a 14-day period. Urine albumin to creatinine ratio and circulating brain (or B-type) natriuretic peptide levels were quantified at baseline as a marker of cardiovascular end-organ damage. Data were analyzed from July 1, 2017, to October 31, 2017. Exposures: Participants were categorized into 4 BP groups: (1) masked hypertension-hypertensive home BP levels (systolic, ≥135 mm Hg; diastolic, ≥85 mm Hg) and nonhypertensive clinic BP levels (systolic, <140 mm Hg; diastolic, <90 mm Hg); (2) white-coat hypertension-nonhypertensive home BP levels (systolic, <135 mm Hg; diastolic, <85 mm Hg) and hypertensive clinic BP levels (systolic, ≥140 mm Hg; diastolic, ≥90 mm Hg); (3) sustained hypertension-hypertensive home and clinic BP levels; and (4) controlled BP-nonhypertensive home and clinic BP levels. Main Outcomes and Measures: Incident stroke and coronary heart disease. Results: Of the 4261 participants, 2266 (53.2%) were women, 3374 (79.2%) were taking antihypertensive medication, and the mean (SD) age was 64.9 (10.9) years. During a median (interquartile range) follow-up of 3.9 (2.4-4.6) years, 74 stroke (4.4 per 1000 person-years) and 77 coronary heart disease (4.6 per 1000 person-years) events occurred. The masked hypertension group had a greater risk for stroke compared with the controlled BP group (hazard ratio, 2.77; 95% CI, 1.20-6.37), independent of traditional cardiovascular risk factors, urine albumin to creatinine ratio, and circulating B-type natriuretic peptide levels. Conversely, masked hypertension yielded no association with coronary heart disease risk. Conclusions and Relevance: In the Japanese general practice population, masked hypertension defined by HBPM may be associated with an increased risk for stroke events. Use of HBPM may improve the assessment of BP-related risks and identify new therapeutic interventions aimed at preventing cardiovascular disease events.