The Reproducibility of Racial Differences in Ambulatory Blood Pressure Phenotypes and Measurements

BACKGROUND: We examined the reproducibility of differences in ambulatory blood pressure (BP) monitoring (ABPM) phenotypes and other parameters (sustained hypertension, masked hypertension, nocturnal hypertension, and nondipping) between African Americans and Whites. METHODS: A total of 420 participants untreated for hypertension attended 2 research visits 1 week apart during which traditional office BP averages and ABPM session averages were determined. We computed percent agreement in ABPM phenotypes across the 2 visits stratified by race and associated kappa statistics with 95% confidence intervals. RESULTS: Whites on average were older, more likely to be male, and had a higher body mass index. There was no significant difference in sleep quality as defined by sleep diary between the 2 races. There were also no significant differences between races in the proportions of participants with sustained hypertension, sustained normotension, or masked hypertension at either testing session. The prevalence of nocturnal hypertension was 59% vs. 75% (P = 0.012) at session 1 and 59% vs. 73% (P = 0.024) at session 2 for Whites and African Americans, respectively, with moderate reproducibility for both (kappas 0.45 and 0.44). Nocturnal BP nondipping had a prevalence 29% vs. 53% (P < 0.001) at session 1 and 29% vs. 47% (P = 0.004) at session 2 for Whites and African Americans, respectively, with fair reproducibility (kappas 0.28 and 0.29). CONCLUSIONS: Our findings support that African Americans indeed exhibit a greater preponderance of abnormal nocturnal BP patterns than Whites. Our work is some of the first to demonstrate that these abnormal patterns are modestly reproducible.