Risk Factors for Stroke Mortality in Men and Women: The Busselton Study

BACKGROUND: Although there have been a number of prospective studies of risk factors for stroke, the Busselton study remains the only Australian study to report such data. The Framingham stroke risk appraisal function has been evaluated in very few populations. This paper presents results of stroke mortality risk factor analyses from the Busselton study and compares the Busselton risk factor coefficients with those based on Framingham data. METHODS: Mortality follow-up to 31 December 1993 on 4872 participants in the Busselton Health Survey 1966-1981 was used for Cox proportional hazards regression analysis of risk factors for death from stroke. Risk factors investigated were systolic and diastolic blood pressures, antihypertensive therapy, diabetes, smoking, body mass index, cholesterol, alcohol, coronary heart disease, atrial fibrillation and left ventricular hypertrophy. RESULTS: The average duration of follow-up was 20 years and a total of 213 individuals died from stroke during the follow-up period. Age, systolic blood pressure, antihypertensive therapy, smoking, cholesterol, alcohol (negatively), coronary heart disease and atrial fibrillation were significantly and independently associated with stroke modality rate. The Cox regression coefficients were generally similar to those from the Framingham study, but there were important differences. CONCLUSIONS: This report has confirmed age, blood pressure, antihypertensive therapy, smoking, and pre-existing cardiovascular disease and diabetes as important risk factors for stroke. The suggestion of a protective effect from moderate alcohol consumption requires further study. The Framingham stroke risk appraisal function should be validated before being recommended for individual stroke risk assessment in other populations.