Thresholds for Ambulatory Blood Pressure Among African Americans in the Jackson Heart Study

Abstract

<div class="section"> <a class="named-anchor" id="S1"> <!-- named anchor --> </a> <h5 class="section-title" id="d9962731e248">Background</h5> <p id="P1">Ambulatory blood pressure (BP) monitoring (ABPM) is the reference standard for out-of-clinic BP measurement. Thresholds for identifying ambulatory hypertension (daytime systolic BP [SBP]/diastolic BP [DBP] ≥ 135/85 mmHg, 24-hour SBP/DBP ≥ 130/80 mmHg, and nighttime SBP/DBP ≥ 120/70 mmHg) have been derived from European, Asian and South American populations. We determined BP thresholds for ambulatory hypertension in a US population-based sample of African Americans. </p> </div><div class="section"> <a class="named-anchor" id="S2"> <!-- named anchor --> </a> <h5 class="section-title" id="d9962731e253">Methods</h5> <p id="P2">We analyzed data from the Jackson Heart Study (JHS), a population-based cohort study comprised exclusively of African-American adults (n=5,306). Analyses were restricted to 1,016 participants who completed ABPM at baseline in 2000-2004. Mean systolic BP (SBP) and diastolic BP (DBP) levels were calculated for daytime (10:00am-8:00pm), 24-hour (all available readings) and nighttime (midnight-6:00am) periods, separately. Daytime, 24-hour, and nighttime BP thresholds for ambulatory hypertension were identified using regression- and outcome-derived approaches. The composite of a cardiovascular disease (CVD) or all-cause mortality event was used in the outcome-derived approach. For this latter approach, BP thresholds were identified only for SBP as clinic DBP was not associated with the outcome. Analyses were stratified by antihypertensive medication use. </p> </div><div class="section"> <a class="named-anchor" id="S3"> <!-- named anchor --> </a> <h5 class="section-title" id="d9962731e258">Results</h5> <p id="P3">Among participants not taking antihypertensive medication, the regression-derived thresholds for daytime, 24-hour, and nighttime SBP/DBP corresponding to clinic SBP/DBP of 140/90 mmHg were 134/85 mmHg, 130/81 mmHg, and 123/73 mmHg, respectively. The outcome-derived thresholds for daytime, 24-hour, and nighttime SBP corresponding to a clinic SBP ≥ 140 mmHg were 138 mmHg, 134 mmHg, and 129 mmHg, respectively. Among participants taking antihypertensive medication, the regression-derived thresholds for daytime, 24-hour, and nighttime SBP/DBP corresponding to clinic SBP/DBP of 140/90 mmHg were 135/85 mmHg, 133/82 mmHg, and 128/76 mmHg, respectively. The corresponding outcome-derived thresholds for daytime, 24-hour, and nighttime SBP were 140 mmHg, 137 mmHg, and 133 mmHg, respectively, among those taking antihypertensive medication. </p> </div><div class="section"> <a class="named-anchor" id="S4"> <!-- named anchor --> </a> <h5 class="section-title" id="d9962731e263">Conclusions</h5> <p id="P4">Based on the outcome-derived approach for SBP and regression-derived approach for DBP, the following definitions for daytime hypertension, 24-hour hypertension, and nighttime hypertension corresponding to clinic SBP/DBP ≥ 140/90 mmHg are proposed for African Americans: daytime SBP/DBP ≥ 140/85 mmHg, 24-hour SBP/DBP ≥ 135/80 mmHg, and nighttime SBP/DBP ≥ 130/75 mmHg, respectively. </p> </div>