Joint effects of risk factors for stroke and transient ischemic attack in a German population: The EPIC Potsdam Study

Background: Single, modifiable risk factors for stroke have extensively been studied. In contrast, differences of their combined effects among stroke and transitoy ischemic attack (TIA) have been rarely investigated. The aim of the present study was to assess single and joint effects of risk factors on the incidence of stroke and TIA and to compare their magnitudes in a large population-based German cohort. Methods: Incident cases of stroke and TIA were identified among 25538 participants (aged 35-65 at baseline) of the European Prospective Investigation into Cancer and Nutrition (EPIC)-Potsdam Study. Relative risks for stroke and TIA related to modifiable risk factors were estimated using Cox proportional hazard models. Results: During 4.3 years of follow-up 100 stroke cases and 112 TIA cases occurred. Incidences of stroke and TIA were 91.7 and 102.7 per 100 000 person-years, respectively. Relative risks for ischemic stroke (RR 5.12, 95% CI 1.49-17.6, p for trend <0.0001) and for TIA (RR 3.08, 95% CI 1.00-9.44, p for trend <0.024) were highest among participants having 4 or 5 modifiable risk factors. 58.5% of ischemic strokes and 26.2% of TIA cases were attributable to the 5 risk factors hypertension, diabetes mellitus, high alcohol consumption, hyperlipidemia, and smoking. Conclusion: Our data indicate that classical risk factors may explain almost 60% of ischemic stroke but only one in four TIA cases. Analysing potential differences of known risk factors between ischemic stroke and TIAs and the identification of other determinants of ischemic attacks are important steps to better explain the burden of stroke. © 2007 Steinkopff Verlag.