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, ≥ 135mmHg; diastolic, ≥ 85mmHg) and nonhypertensive clinic BP levels (systolic, < 140mmHg; diastolic, < 90mmHg); (2) white-coat hypertension-nonhypertensive home BP levels (systolic, < 135mmHg; diastolic, < 85mmHg) and hypertensive clinic BP levels (systolic, ≥ 140mmHg; diastolic, ≥ 90mmHg); (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.