Sex Differences in Blood Pressure and Cardiovascular Disease in the UK Biobank: A Prospective Cohort Study

BACKGROUND: Recent studies show that cardiovascular disease (CVD) risk increases from a lower nadir of systolic blood pressure (SBP) in women than men, and increases thereafter at a greater rate. This has led to a suggestion that sex-based SBP thresholds are required. We investigated sex differences in the associations of SBP and incident atherosclerotic CVD. METHODS: This prospective study included 420,649 UK Biobank participants with no prior history of CVD. Age-adjusted sex-specific risks, relative risks (RRs), and risk differences (RDs) relating SBP to CVD were estimated using Poisson and Cox regression. RESULTS: Over 13.6 years of follow-up, there were 28,628 CVD events. CVD risks across BP levels showed a "J-shape," and were higher in men than women at all BP levels. The lowest risks were at SBP 100-<105 mmHg (events per 10,000 person-years [95% CI]: 15.6 [11.8-19.4]) and 110-<115 (47.2 [41.4-53.0]) among women and men, respectively. Compared with SBP 100-<110, sex-specific RRs at above 120 were higher in women than men, but RDs were higher in men than women at all levels of SBP. Compared to men at 110-<115 (ie, the men with least risk), risks in women were lower at all levels of SBP below 170. CONCLUSIONS: CVD risk is lowest for women at a slightly lower SBP than men and RRs for CVD increase with SBP at a slightly steeper rate in women. However, both risks and RDs in women are never greater than in men. This evidence does not support lower thresholds for diagnosis of hypertension in women.