Family history and stroke: a community case-control study in Asturias, Spain

Family history of stroke has been considered as a risk factor for stroke, but this relationship is controversial. Some, but not all, studies have found an independent association between family history of stroke and stroke. This study examines the relationship between family history of stroke and all stroke types combined, cerebral infarction and intraparenchymatous haemorrhage.

This is an incidence type, population-based case-control study. Cases were defined following WHO criteria and controls were randomly selected from the study-base population. Family history of stroke was obtained by medical interview. A total of 470 cases and 477 controls, aged 40-85 years, form the subjects of the study.

Family history of stroke in a first-degree relative is an independent risk factor for all stroke types combined, multivariate adjusted odds ratio (OR) 1.74, 95% confidence interval (CI) 1.24-2.44, for cerebral infarction, OR = 1.79 (95% CI 1.25-2.56), but not for intraparenchymatous haemorrhage, OR = 1.71 (95% CI 0.91-3.17). Risk of all stroke types combined was independently associated with a positive history of father with stroke OR = 1.93 (1.19-3.54) with a positive history of sibling with stroke, OR = 1.67 (95% CI 1.03-2.71) and a borderline significant association with a positive history of mother with stroke OR = 1.45 (95% CI 0.92-2.29). Cerebral infarction was independently associated with a positive history of father with stroke OR = 2.05 (95% CI 1.17-3.59), a positive history of sibling, OR = 1.69 (95% CI 1.01-2.84) and a borderline significant association with a positive history of mother with stroke OR = 1.58 (95% CI 0.97-2.56). Intracerebral haemorrhage was not significantly associated with a positive history of father with stroke OR = 1.39 (0.55-3.58) with a positive history of sibling, OR = 1.83 (95% CI 0.77-4.40), or with a positive history of mother with stroke OR = 1.36 (95% CI 0.59-3.09).

Family history of stroke is found in this study to be an independent risk factor for all stroke types combined and for cerebral infarction. Genetic factors may be involved, but it cannot be ruled out that the observed relationship is confounded by other risk factors, especially family aggregation of life-styles.