By Cole Petrochko, Staff Writer, MedPage Today
Full Story: http://www.medpagetoday.com/Cardiology/Strokes/41131
A pooled analysis of stroke risk among smokers showed no significant difference in risks between sexes(relative risk ratio 1.06, 95% CI 0.99-1.13), according to research from Rachel Huxley, DPhil, of the University of Minnesota in Minneapolis, and colleagues. Their analysis concluded that: “Compared with nonsmokers, the excess risk of stroke is at least as great among women who smoke compared with men who smoke.”
However, by global region, there was a significantly greater smoking-related stroke risk seen in Western women than Western men (RRR 1.10, 95% CI 1.02-1.18) and no difference seen between Asian women and men (RRR 0.97, 95% CI 0.87-1.09), they wrote online in the journal Stroke.
Prior research has shown that adverse effects of smoking related to lung cancer and coronary heart disease are greater in women.
While smoking is an independent risk for ischemic and hemorrhagic stroke in men and women, no studies have looked at sex differences in these risks.
The authors gathered data through a review of population-based cohort studies published from 1966 to 2013 and included a study pool of 81 prospective cohorts with a total 3,980,359 participants and 42,401 strokes. Outcomes in studies were presented as sex-specific estimates for stroke and measured smokers against nonsmoking individuals.
The primary end point was fatal and nonfatal stroke. Outcomes were grouped by sex, age, and global region.
By region, the total study population was comprised of 31% participants in Asian countries, 62% of those from the U.S., 4% from Europe, and 3% from Australia or New Zealand.
Pooled data showed that, versus nonsmokers, current smokers had an 83% increased risk of stroke in women (95% CI 1.58-2.12) and 67% in men (95% CI 1.49-1.88). The relative risk ratio of these pooled data showed no significant difference in stroke risk between women and men (P=0.10).
There was no significant difference in stroke risk between younger and older patients, regardless of sex. However, there was a significantly greater risk for stroke in women from Western countries than men, while there was no difference seen between men and women in Asian countries.
There was no sex difference for ischemic strokes. There was a significantly greater risk among women who smoked compared with men for hemorrhagic stroke (RRR 1.17, 95% CI 1.02-1.34, P=0.02).
Compared with never smokers, there was a 17% increased risk of stroke in former women smokers and 8% increased risk among men who used to smoke, though there was no significant difference between sexes for this risk.
The authors noted that the difference by global region “is real and potentially an underestimate of the true difference for several reasons,” which they explained may be due to sex differences in smoking population density, the number of cigarettes smoked per day may differ by sex, and an overall under-reporting of smoking habits in women of some ethnic groups.
They also cautioned that their study was limited by a lack of standardization of study design and duration across studies, different classifiers for groups in each study (such as nonsmokers being defined as never smokers in one study and as a person not currently smoking in another), between-study heterogeneity, and a lack of data on duration of smoking between studies.
The study was supported by a Niels Stenson Fellowship.
The authors had no other conflicts of interest to declare.
Primary source: Stroke