Thresholds for Ambulatory Blood Pressure Among African Americans in the Jackson Heart Study
Background—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.
Methods—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.
Results—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.
Conclusions—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.
- Received December 21, 2016.
- Revision received March 22, 2017.
- Accepted April 10, 2017.