Nirali Vora, MD
Peters SAE, Huxley RR, Woodward M. Smoking as a Risk Factor for Stroke in Women Compared With Men: ASystematic Review and Meta-Analysis of 81 Cohorts, Including 3,980,359 Individuals and 42,401 Strokes. Stroke. 2013.
Are women at a higher risk for stroke if they smoke? Prior studies showed women have 25% greater risk of smoking related heart disease compared to men, but we did not know if there was any gender disparity in strokes and tobacco use.
To address this, Peters, Huxley, and Woodward performed a pooled analysis of 81 population-based cohort studies, comprising ~4 million patients and ~42,000 strokes. The major finding was that there wasn’t actually any gender difference between fatal and non-fatal stroke and current smoking. Among a sub-group, “Occidental” (USA, Europe, Australia, New Zealand) women may have 10% increased stroke risk compared to men. The authors suggest the lack of disparity among Asian cohorts may be from underestimates because (1) it is too early to see harmful effects in regions where women more recently have become smokers (2) overall rates of smoking are low, and (3) mis-categorization from cultural inappropriateness of identifying women as smokers.
Personally, I interpret the equal stroke risk in the whole and Asian cohorts as reason to ensure women and men are being equally targeted in smoking cessation and stroke prevention campaigns, especially in low- and middle-income countries where current health policy might include a workplace ban or tobacco tax and education that might not directly affect women. Future studies should focus on measuring the impact of smoking cessation programs on reducing stroke to identify if any gender disparity emerges on the treatment end. I wonder if that is why “Occidental” female smokers showed some higher risk (after some statistical magic), since these high income countries have had smoking cessation programs in place for years. Attention must be paid to these issues in other LMIC regions as the WHO/UN have a global goal to reduce tobacco consumption by 30% and non-communicable diseases (including stroke) by 25% by 2025.