Nighttime Blood Pressure Dipping is Attenuated in Young and Apparently Healthy Black Adults Compared to White Adults

Abstract

In America, Black adults are 30% more likely to die from cardiovascular disease (CVD) compared to White adults, and more than half of this racial disparity in CVD‐related mortality may be attributed to the substantially greater prevalence of high blood pressure (BP) in Black adults. Furthermore, compared to White adults with hypertension, Black adults with hypertension are less likely to exhibit a nocturnal reduction in BP (i.e., “dipping”). Importantly, non‐dipping BP is associated with target organ damage and increased CVD risk. However, it is unclear whether young and apparently healthy Black adults exhibit reduced BP dipping compared to their White peers.PURPOSETherefore, the purpose of this preliminary investigation was to determine whether there are racial differences in BP dipping using ambulatory BP monitoring (ABPM), including 24‐hour‐, daytime‐, and nighttime‐BP, in young and apparently healthy Black and White adults.METHODSWe obtained clinical BP and 24‐hour ABPM readings in 10 self‐identified White adults (5M/5F; age: 21.6±4.4 yrs; BMI: 23.8±2.9 kg/m2; Mean±SD) and 7 self‐identified Black adults (3M/4F; age: 21.7±3.5 yrs; BMI: 25.1±2.8 kg/m2). The ABPM monitors were programmed to record BP every 20 and 30 minutes during each participants daytime‐ and nighttime‐period, respectively. True daytime‐ and nighttime‐BP periods were adjusted during analysis based upon participant activity logs. We defined “non‐dipping” as a failure to achieve a dipping ratio of <0.90 (night‐to‐day BP ratio). BP data were compared using independent t‐tests and the Fisher’s exact test was used to compare dipping frequency between races (α=0.05).RESULTSClinically measured BP (systolic/diastolic) was not different (P>0.05) between White (117±9/67±6 mmHg) and Black (124±12/70±9 mmHg) adults. There was also no difference (P>0.05) in 24‐hour‐BP between White (117±11/66±7 mmHg) and Black (114±14/63±7 mmHg) adults. Likewise, daytime‐BP was not different (P>0.05) between White (122±12/71±8 mmHg) and Black (116±14/66±8 mmHg) participants, nor was there a difference in nighttime‐BP (P>0.05) between White (102±9/51±4 mmHg) and Black (105±13/54±7 mmHg) adults. However, systolic BP dipping was attenuated (P=0.04) in Black (0.90±0.05) compared to White (0.84±0.07) adults. Non‐dipping of systolic BP was observed in 5 of 7 Black participants and 2 of 10 White participants (P=0.06). Diastolic BP dipping in Black adults was 0.79±0.06 and White adults was 0.73±0.09 (P=0.05). Non‐dipping of diastolic BP was observed in 1 of 7 Black participants and 1 of 10 White participants (P=1.00).CONCLUSIONSThese preliminary data suggest that despite similar clinical and 24‐hour ambulatory BP compared to White adults, young and apparently healthy Black adults exhibit impaired BP dipping, which may contribute to increased likelihood of CVD.