CVD risk associated with lower SBP range in women than in men
Sex Differences in Blood Pressure Associations With Cardiovascular Outcomes
Introduction and methods
A systolic blood pressure (SBP) of 120 mm Hg has long been considered the normal upper limit in adults. Epidemiologic findings have shown that CVD risk continuously increases with increasing SBP starting at 120 mm Hg . Although it is known that adult BP levels are on average lower in women than in men , it remains uncertain whether a lower SBP range should be considered as normal in women compared to men. This study investigated sex differences in BP associations with CV outcomes.
Data from standardized SBP measurements from 27542 subjects (54% women) without CVD at baseline from four community-based cohort studies (the Framingham Heart Study, Multi-Ethnic Study of Atherosclerosis, Atherosclerosis Risk in Communities Study, and Coronary Artery Risk Development in Young Adults Study) were analyzed. Age and race distributions were similar between men and women. A total of 7424 participants (44% women) developed non-fatal or fatal CVD during a follow-up of 28±12 years. This involved 3405 MI events, 4081 HF events and 1901 stroke events. SBP was stratified into categories of 10 mm Hg increments from <100 mm Hg to ≥160 mm Hg. SBP categories were related with incident CVD using cohort-stratified Cox proportional hazards models. Competing risks were accounted for and HR’s were adjusted for traditional risk factors.
- In sex-pooled analyses, the SBP threshold for incident MI and HF was 120-129 mm Hg. The BP threshold associated with incident stroke was 130-139 mm Hg.
- In sex-specific analyses, risk of incident CVD started to increase at lower SBP thresholds in women compared to men. A SBP of 100-109 mm Hg (relative to SBP <100 mm Hg) was associated with incident CVD in women. In men, risk of incident CVD was associated with SBP levels starting from 130-139 mm Hg. Remarkably, the magnitude of risk in men at a SBP threshold of 130-139 mm Hg was similar to the risk seen in women at a SBP threshold of 100-109 mm Hg (multivariable-adjusted HR for incident CVD is 1.26 [95%CI 1.02-1.57] at SBP 130-139 mm Hg in men vs. 1.25 [95%CI 1.04-1.51] at SBP 100-109 mm Hg in women).
- Results were similar for associations of SBP with incident MI, HF, and stoke. The risk for MI in women with SBP 110-119 mm Hg (HR 1.64, 95%CI 1.20-2.25) was comparable with risk for MI in men with SBP≥160 mm Hg (HR 1.62, 95%CI 1.14-2.30). Risk for HF in women with SBP 110-119 mm Hg (HR 1.42, 95%CI 1.11-1.82) was comparable with risk for HF in men with SBP 120-129 mm Hg (HR 1.40, 95%CI 1.04-1.90). Risk for stroke in women with SBP 120-129 mm Hg (HR 1.53, 95%CI 1.07-2.21) was comparable with risk for stroke in men with SBP 140-149 mm Hg (HR 1.50, 95%CI 0.85-2.64).
- Results were similar in analyses excluding participants taking antihypertensive medication, excluding DBP adjustment, and relating DBP with CVD risk. Results were also similar when analyses were stratified by age, race, and cohort.
- Associations of SBP with incident CVD were more pronounced in younger (<52 years) vs. older women (≥52 years) (P<0.001). No age interaction was seen in men.
Increased CVD risk is associated with lower SBP ranges in women compared to men. These results suggest that the definition of an optimal SBP may need to be sex-specific. Further studies are needed for the validation of these results and prospective studies are necessary to determine whether treatment targets for hypertension medication should be lower for women compared to men.