Stroke incidence remains higher in men, despite strong risk factors for stroke in women
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An analysis of more than 470,000 patients from the UK Biobank cohort study demonstrated that, while several risk factors strongly correlated with stroke risk in women compared with men, the rate of stroke remained higher among men.
Specifically, the findings linked hypertension, smoking and low socioeconomic status with a greater risk for any type of stroke in women compared with men.
“It is increasingly clear that there are important differences between women and men in several disease areas, including stroke. What is not well-established is whether the impact of major risk factors is similar between the sexes,” Sanne Peters, PhD, senior lecturer at the George Institute for Global Health at the University of Oxford, told Healio Neurology. “In this study, we used data from the UK Biobank to examine the relationship between several major stroke risk factors and the risk of stroke, including stroke subtypes, by sex.”
Peters and colleagues included 471,971 participants (56% women) from the UK Biobank study in their analysis. They restricted the study population to participants with no self-reported history of cardiovascular disease.
The researchers used Cox models to produce adjusted HRs and women-to-men ratios of HRs (RHR) for stroke in connection with seven risk factors including hypertension, smoking status, diabetes, body anthropometry, cholesterol, atrial fibrillation and socioeconomic status. Primary study endpoints included the rate of fatal or non-fatal ischemic stroke, hemorrhagic stroke and all stroke as defined by ICD-10 codes.
The mean age at baseline was 56 years. The researchers observed higher BP levels in men; men were also more likely to have ever smoked. The researchers reported higher rates of diabetes in men (6%) compared with women (3%). Peters and colleagues also found higher rates of overweight or obesity in men (74%) compared with women (59%) at baseline.
Over a median follow-up period of 9 years, 4,662 strokes occurred, 44% of which were in women. Specifically, this included 3,563 ischemic strokes (40% in women) and 790 hemorrhagic strokes (47% in women). The incidence rate per 10,000 person years was 8.66 in women and 13.96 in men for any stroke and 6.06 in women and 11.35 in men for ischemic stroke and 1.56 in women and 2.23 in men for hemorrhagic stroke.
The researchers observed similar relationships between increases in BP, body anthropometry and lipids, diabetes and atrial fibrillation and any type of stroke in men and women. However, hypertension (women-to-men ratio of HRs [RHR] = 1.36 [1.26-1.47]) smoking (RHR = 1.18 [1.02-1.36]) and a low socioeconomic status (RHR = 1.17 [1.03-1.33]) correlated with a greater HR of any stroke in women than men. Peters and colleagues found that diabetes correlated with a higher HR for ischemic stroke in women than in men (RHR = 1.25 [1-1.56]). They also observed a relationship between atrial fibrillation and a higher HR for hemorrhagic stroke in women than in men (RHR = 2.8 [1.07-7.36]).
“We demonstrated that hypertension, smoking and a low socioeconomic status were associated with a greater excess risk for any stroke in women than men,” Peters said. “Diabetes was associated with a greater excess risk for ischemic stroke in women than men and atrial fibrillation was associated with a greater excess risk of hemorrhagic stroke in women than men.”
However, despite “the stronger relationship between these risk factors and stroke in women,” the rate of stroke remained higher in men, she continued.
“Our study was not designed to find reasons for these sex differences, so this needs to be determined in future studies,” Peters said. “In terms of clinical implications, our study highlights the presence of clinically meaningful sex differences and the impact of common risk factors on stroke incidence. Clinical guidelines therefore may need to include sex-specific recommendations for the management of these risk factors to reduce the burden of stroke most efficiently in both sexes.”