Background and purpose: Large cohort studies on relationship between family history of stroke (FHS) and stroke risk are lacking in Asians. We aimed to systematically evaluate the association of FHS with stroke risk in a cohort study of 0.5 million Chinese adults.
Methods: Information about FHS was self-reported. The median follow-up time was 7.16 years and the end-point of follow-up was incident stroke, which was entered directly into the China Kadoorie Biobank system. Multivariate analyses were performed with Cox proportional hazards model, and interaction analyses were carried using likelihood-ratio tests.
Results: Compared with participants without FHS, the hazard ratio (HR) (95% confidence interval, CI) of stroke for participants with FHS was 1.50 (1.46-1.55). The HRs increased with the number of first degree relatives with stroke (HRs=1.41, 1.98 and 2.47 for 1, 2 and ≥3 relatives, respectively, Ptrend <0.001). The HRs were 1.57 (95% CI: 1.50-1.66) and 1.49 (95% CI: 1.45-1.54) for sibling history and parental history, respectively. Similar associations with offspring stroke risk were observed between paternal history (HR=1.48, 95% CI: 1.43-1.54) and maternal history (HR=1.49, 95% CI: 1.43-1.55). Moreover, significant interactions were detected between FHS and health-risk behaviors (tobacco smoking and alcohol drinking).
Conclusions: FHS is an independent risk factor for stroke in Chinese. The more first degree relatives are affected by stroke, the higher are individuals' risk of suffering from stroke. The management of the health-risk behaviors for reducing stroke should be highlighted, especially for the individuals with FHS.
Keywords: Association; Cohort study; Family history; Stroke.