Introduction:
Despite indications that blood pressure is positively related to vascular disease, with no evidence of a threshold, recommendations for population improvements in cardiovascular health are largely focused on populations with hypertension or prehypertension. Here we compare the impact of meeting the Healthy People 2020 goal of a 10% reduction in the proportion of adults with hypertension, with a 2 mm Hg reduction in population-wide levels of systolic blood pressure (SBP) on the incidence of heart failure (HF), coronary heart disease (CHD), and stroke.
Methods:
In the biracial Atherosclerosis Risk in Communities Study (n=15,744) cohort, blood pressure was measured at baseline (1987-1989) using standardized methodology. Thresholds to define prehypertension (SBP=120-139 or DBP=80-89 mm Hg) and hypertension (SBP ≥140 or DBP ≥ 90) were from JNC7. A first hospitalization with discharge diagnosis code of ‘428’ defined incident HF. Incident hospitalized (definite or probable) CHD and stroke was classified by physician panel. We used multivariable regression to estimate incidence rate differences (IRD) for HF, CHD, and stroke that could be associated with a 10% reduction in the proportion of individuals with prehypertension and hypertension, as compared to a population-wide 2 mm Hg decrease in SBP.
Results:
At baseline, there were 31% African Americans and 13% Caucasians with hypertension, and 38% African Americans and 33% Caucasians with prehypertension. Over a mean of 18.7 years of follow up, age-adjusted incidence rates for HF, CHD, and stroke were higher among African Americans than Caucasians. After adjusting for covariates measured at study baseline, a hypothetical 10% reduction in the proportions of individuals with hypertension and pre-hypertension was associated with a larger estimated effect for HF compared with CHD and stroke. For the 10% reduction in those with hypertension, we estimated 2/100,000 person-years (PY) and 8/100,000 PY fewer incident HF hospitalizations in Caucasians and African Americans, respectively. In contrast, a population-wide blood pressure reduction approach of 2 mm Hg was associated with an estimated 24/100,000 PY and 39/100,000 PY fewer incident HF events in Caucasians and African Americans, respectively. When extrapolated to the 2010 US population aged greater than 45 years, hypothetical interventions that shift the population distribution of SBP by 2 mm Hg potentially result in an additional reduction of 22,000 HF hospitalizations, 17,000 CHD events, and 11,000 stroke events annually when compared to a primary prevention approach aimed at populations with hypertension and pre-hypertension.
Conclusion:
Modest, population-wide shifts in SBP may produce greater reductions in HF, CHD, and stroke events than can be achieved by only targeting reductions for those with hypertension, particularly among African Americans.
HYPOXIA-HYPEROXIA ADAPTATION AND INCREASED EXERCISE CAPACITY IN PATIENTS WITH CORONARY HEART DISEASE
