What else adds to hypertension in predicting stroke? An incident case-referent study

OBJECTIVES: To examine to what extent traditional biomedical risk factors and social factors can predict, separately or jointly, first-ever stroke event, and to explore to what extent other risk factors might add to hypertension/elevated blood pressure as a stroke risk factor. DESIGN: An incident case-referent study. SETTING: The study was nested within the Västerbotten Intervention Program (VIP) and the Northern Sweden MONICA cohorts. SUBJECTS: The study involves 129 stroke cases with two randomly selected referents per case from the same study cohorts. RESULTS: History of diabetes, daily smoking, obesity (body mass index greater than or = 30 kg m(-2)), hypertension and living as an unmarried person were associated with an increased risk in univariate analysis. However, in the multivariate logistic regression analysis, only hypertension, diabetes and single marital status remained significant. There was a statistically significant interaction between hypertension and smoking and stroke. Interaction of possible clinical relevance was also observed between hypertension, history of diabetes and stroke. CONCLUSIONS: The study both emphasizes the multifactorial nature of stroke and illustrates that knowledge of interactions offers different strategic approaches when preventing stroke in clinical work. It is important, but not enough, to focus on blood pressure control. Diabetes prevention as well as prevention of smoking must also be considered as factors of major importance.