Comparison of the Sex-Specific Associations Between Systolic Blood Pressure and the Risk of Cardiovascular Disease: A Systematic Review and Meta-analysis of 124 Cohort Studies, Including 1.2 Million Individuals

Peters SAE, Huxley RR, and Woodward M
Stroke. 2013;44:2394-2401

Background

Estimates of disease burden of elevated blood pressure assume that the association between systolic blood pressure (SBP) and cardiovascular disease (CVD) is similar for men and women. Large-scale pooling studies have however given inconsistent results [1-4]. While one study showed a slightly higher risk of SBP-related stroke for men as compared to women [1], other studies did not find a sex difference for the association between SBP and fatal stroke [2,4].
Sex differences in hazards have been found for ischemic heart disease (IHD)[1] and acute myocardial infarction (MI) [3]. However, total IHD, fatal IHD or nonfatal MI did not show such an effect [4].
There has not been a systematic comparison of the relation between SBD and CVD between the sexes. This study therefore performed a systematic review with meta-analysis of prospective cohort studies of the sex-specific associations between SBP with stroke and IHD. A total of 24 studies comprising 124 cohorts was analysed, encompassing data from 1197472 individuals (44% women), who experienced 26176 strokes and 24434 IHD events.

Main results

• A pooled multiple-adjusted RR for a 10mmHg increment in SBP showed a 23% higher risk (95%CI: 1.20-1.25) of stroke in women and 24% higher risk (95%CI: 1.20-1.28) for stroke in men. There was no statistically significant sex difference for the risk of stroke (RRR: 0.98, 95%CI: 0.96-1.01, P=0.13).
• No difference in the RRR (women:men ratio of RRs) for stroke was seen based on different age groups, nor for regions or studies. There was some evidence that suggested a sex difference for hemorrhagic stroke (RRR: 0.94, 95%CI: 0.89-0.99).
• The pooled multiple-adjusted RR for the association between SBP and combined IHD showed a 13% higher risk with each 10 mmHg increment in SBP for both women (95%CI: 1.10-1.16) and men (95%CI: 1.10-1.15). Thus, there was no sex difference (pooled RRR: 1.oo, 95%CI: 0.97-1.04, P=0.85).
• No difference in the RRR for IHD was seen based on age-groups. As compared to women, men from Asia had a slightly but significantly increased risk of IHD associated with increased SBP: the pooled RRR of 21 cohorts of non-Asian countries was 1.02 (95%CI: 1.00-1.05) as compared to 0.94 (95%CI: 0.92-0.97) based on 54 Asian cohorts.

Conclusion

This meta-analysis of data of ~1.2 million individuals demonstrates that the association between SBP and risk of IHD and stroke is largely similar in men and women. Both genders have approximately 25% extra risk of stroke and ~15% risk of IHD with each 10 mmHg increment in SBP. However, prevalence of high SBP and other CVD risk factors likely vary between the sexes.

References

1. Lewington S, Clarke R, Qizilbash N, et al. Prospective Studies Collaboration. Age-specific relevance of usual blood pressure to vascular mortality: a meta-analysis of individual data for one million adults in 61 prospective studies. Lancet. 2002;360:1903–1913.
2. O’Donnell MJ, Xavier D, Liu L, et al.; INTERSTROKE Investigators. Risk factors for ischaemic and intracerebral haemorrhagic stroke in 22 countries (the INTERSTROKE study): a case-control study. Lancet. 2010;376:112–123.
3. Yusuf S, Hawken S, Ounpuu S, et al. INTERHEART Study Investigators. Effect of potentially modifiable
risk factors associated with myocardial infarction in 52 countries (the INTERHEART study): case-control study. Lancet. 2004;364:937–952.
4. Lawes CM, Rodgers A, Bennett DA, et al. Asia Pacific Cohort Studies Collaboration. Blood pressure and cardiovascular disease in the Asia Pacific region. J Hypertens. 2003;21:707–716.

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