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Association of Ambulatory BP With CVD in African Americans
Study Questions:
What is the association between daytime and nighttime blood pressure (BP) levels measured outside the clinic among African American individuals with cardiovascular disease (CVD) and all-cause mortality independent of BP levels measured inside the clinic?
Methods:
The investigators conducted a prospective cohort study and analyzed data from 1,034 African American participants in the Jackson Heart Study who completed ambulatory BP monitoring at baseline (September 26, 2000, to March 31, 2004). Mean daytime and nighttime BPs were calculated based on measurements taken while participants were awake and asleep, respectively. Data were analyzed from July 1, 2017, to April 30, 2019. The main outcomes measures were CVD events, including coronary heart disease and stroke, experienced through December 31, 2014, and all-cause mortality experienced through December 31, 2016. The associations of daytime BP and nighttime BP, separately, with CVD events and all-cause mortality were determined using Cox proportional hazards regression models.
Results:
A total of 1,034 participants (mean [standard deviation] age, 58.9 [10.9] years; 337 [32.6%] male; and 583 [56.4%] taking antihypertensive medication) were included in the study. The mean daytime systolic BP (SBP)/diastolic BP (DBP) was 129.4/77.6 mm Hg, and the mean nighttime SBP/DBP was 121.3/68.4 mm Hg. During follow-up (median [interquartile range], 12.5 [11.1-13.6] years for CVD and 14.8 [13.7-15.6] years for all-cause mortality), 113 CVD events and 194 deaths occurred. After multivariable adjustment, including in-clinic SBP and DBP, the hazard ratios (HRs) for CVD events for each SD higher level were 1.53 (95% confidence interval [CI], 1.24-1.88) for daytime SBP (per 13.5 mm Hg), 1.48 (95% CI, 1.22-1.80) for nighttime SBP (per 15.5 mm Hg), 1.25 (95% CI, 1.02-1.51) for daytime DBP (per 9.3 mm Hg), and 1.30 (95% CI, 1.06-1.59) for nighttime DBP (per 9.5 mm Hg). Nighttime SBP was associated with all-cause mortality (HR per 1-SD higher level, 1.24; 95% CI, 1.06-1.45), but no association was present for daytime SBP (HR, 1.13; 95% CI, 0.97-1.33) and daytime (HR, 0.95; 95% CI, 0.81-1.10) and nighttime (HR, 1.06; 95% CI, 0.90-1.24) DBP.
Conclusions:
The authors concluded that among African American individuals, higher daytime and nighttime SBPs were associated with an increased risk for CVD events and all-cause mortality independent of BP levels measured in the clinic.
Perspective:
This community-based study of African American individuals reports that higher daytime and nighttime SBPs were each associated with an increased risk of CVD events and all-cause mortality. Furthermore, higher daytime and nighttime DBPs were both associated with an increased risk of CVD events in unadjusted models and after multivariable adjustment, including clinic BP. These data suggest that measurement of daytime and nighttime BP using ambulatory monitoring (ABPM) during a 24-hour period may help identify African American individuals who have an increased CVD risk. Additional studies are indicated to assess whether administration of antihypertensive drugs at bedtime versus in the morning or a combination of both is more effective for mitigating CVD risk among African American individuals.
Keywords: African Americans, Antihypertensive Agents, Blood Pressure, Blood Pressure Monitoring, Ambulatory, Coronary Disease, Diastole, Primary Prevention, Stroke, Systole, Vascular Diseases
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