A significant portion of the increased cardiovascular disease risk seen in black adults may stem from hypertension, according to a prospective cohort study published by a team led by Donald Clark III, MD, of the University of Mississippi in Jackson.
The analysis showed that about one-third of cardiovascular disease can be traced to hypertension in black adults, and the influence was much stronger in individuals under 60, suggesting that early interventions to maintain normal blood pressure have the potential to reduce risk in this population.
Hypertension is already known to be the leading contributor to cardiovascular disease (CVD) in the United States, and non-Hispanic black adults experience it at a rate of 55%, higher than any other group.
The researchers used data from the Jackson Heart Study (JHS) and the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study to determine the association between CVD and hypertension, and NHANES 2011-2014 to examine the rate of hypertension among non-Hispanic black adults in the United States.
At baseline, among 12,497 participants In the JHS and REGARDS studies, 33% had normal blood pressure, 41% had elevated BP, and 36% had hypertension. In the NHANES cohort, 35% had normal BP, 12% had elevated BP, and 53% had hypertension.
In the combined JHS and REGARDS cohorts, subjects with elevated BP and hypertension had greater odds of taking cholesterol-lowering medication compared to those with normal BP: 8.5% of normotensive patients and 9.9% of those with elevated BP were on medication, compared with 26.0% of hypertensive patient, emphasizing the importance of effective hypertension management, the investigators noted.
Similarly, 9.9% of patients with normal BP and 14.7% of those with elevated BP had diabetes, compared with 26.0% of hypertensive patients. Hypertensive patients were also less likely to have graduated from high school (81%) than were those with elevated BP (84.5%) and normal BP (89.9%), and they had a higher mean body mass index (31.4 kg/m2) than their counterparts with elevated (29.6) and normal (28.8) BP.
After a maximum of 14.3 years of follow-up, 9.9% of participants experienced a CVD event. The researchers calculated the population attributable risk (PAR) using the prevalence of hypertension from the NHANES dataset and the multivariable-adjusted association between elevated versus normal BP and hypertension versus normal BP in the JHS and REGARDS data.
“Hypertension was independently associated with incident [coronary heart disease], heart failure, and stroke,” the investigators wrote. The PARs associated with hypertension were 32.5% (95% CI, 20.5-43.6%) for CVD, 42.7% (95% CI, 24.0-58.4%) for coronary heart disease, 21.6% (95% CI, 0.6-40.8%) for heart failure, and 38.9% (95% CI, 19.4-55.6%) for stroke.
Men and women had similar PAR values for CVD (33.9% vs. 31.1%). Participants younger than 60 had a higher value of PAR associated with hypertension than older participants (54.6% [95% CI, 37.2-68.7%] vs. 32.0% [95% CI, 11.9-48.1%]). Dr. Clark and his coinvestigators noted that the “most substantial finding” of the study was PAR of 69% for stroke associated with hypertension found in patients younger than 60 years. “These data suggest that interventions to maintain normal BP across the life course may reduce the incidence of CVD in this population,” they concluded.
The REGARDS study was funded by NIH and the American Heart Association. The JHS study was funded by Jackson State University, Tougaloo College, the Mississippi State Department of Health, and the University of Mississippi Medical Center. The authors have extensive financial ties to pharmaceutical companies.
SOURCE: JAMA Card. 2019. October 23, 2019. doi:10.1001/jamacardio.2019.3773.