Regression to the mean in home blood pressure: Analyses of the BP GUIDE study.

Abstract

The aim of our study was to estimate the size of regression to the mean with home blood pressure (BP) monitoring and compare with that for office BP. Office and home BP measures were obtained from the BP GUIDE (value of central Blood Pressure for GUIDing managEment for hypertension) study, in which 286 patients had BP measured every 3months for 12months. Patients were categorized by 10mmHg strata of baseline BP, and regression to the mean measures was calculated for home and office BP. High baseline home BP readings tended to be lower on long-term follow-up, and low baseline readings tended to be higher. For example, patients in the group with mean baseline home systolic BP≥150mmHg had a mean baseline systolic BP of 156mmHg, which fell to 143mmHg at 12months; and patients in the group with mean baseline home systolic BP<120mmHg had a mean baseline systolic BP of 113mmHg which rose to 120mmHg at 12months. Similar patterns were seen in intervention and control groups, and for diastolic BP. The regression dilution ratio for home systolic BP and diastolic BP was 0.52 and 0.64, respectively, compared to 0.40 and 0.55 for office systolic BP and diastolic BP, respectively. Home BP is subject to regression to the mean to a similar degree as office BP. These findings have implications for the diagnosis and management of hypertension using home BP.