Daytime, Nighttime Blood Pressure Linked with CVD in African Americans

Daytime and nighttime ambulatory blood pressure were closely linked with the risk for cardiovascular disease (CVD) in African Americans, according to a new study.

The paper, appearing in JAMA Cardiology, was a prospective cohort study looking at data from 1,034 African American participants from the Jackson Heart Study who had undergone and completed ambulatory blood pressure monitoring at study baseline. The researchers, seeking to determine whether daytime and nighttime blood pressure levels taken outside of the clinic were linked with CVD independent of clinical blood pressure levels looked at mean daytime and nighttime blood pressure measurements taken when participants were both awake and asleep, respectively. The primary study outcomes were CVD events such as coronary heart disease and stroke, and all-cause mortality. The researchers used Cox proportional hazard models to determine associations between daytime and nighttime measurements and CVD.

Mean daytime systolic/diastolic blood pressure was 129.4/77.6 mm Hg, and mean nighttime systolic/diastolic was 121.3/68.4 mm Hg. The hazard ratios for CVD events for each higher SD were 1.53 for daytime systolic blood pressure and 1.48 for nighttime systolic blood pressure, 1.25 for daytime diastolic blood pressure, and 1.30 for nighttime diastolic blood pressure. They authors reported an association between nighttime systolic blood pressure and all-cause mortality for each 1-SD higher level (but no such association for daytime systolic blood pressure and daytime and nighttime diastolic blood pressure.

“Among African American individuals, higher daytime and nighttime systolic blood pressures were associated with an increased risk for CVD events and all-cause mortality independent of blood pressure levels measured in the clinic,” the researchers wrote. “Measurement of daytime and nighttime blood pressure using ambulatory monitoring during a 24-hour period may help identify African American individuals who have an increased CVD risk.”