Comparison of risk factors for stroke incidence and stroke mortality in 20 years of follow-up in men and women in the Renfrew/Paisley study in Scotland

Background and Purpose-The aim of this study was to relate risk factors in middle-aged men and women to stroke incidence (defined by having a hospital discharge with a main diagnosis of stroke) and compare this with the associations between risk factors and stroke mortality. Methods-In the early to mid-1970s, when they were 45 to 64 years of age, 7052 men and 8354 women from the Renfrew/Paisley prospective cohort study in Scotland were screened. Risk factors measured included blood pressure, blood cholesterol and glucose, respiratory function, cardiothoracic ratio, smoking habit, height, body mass index, preexisting coronary heart disease, and diabetes. These were related to stroke incidence over 20 years of follow-up. Results-Diastolic and systolic blood pressure, smoking, cardiothoracic ratio, preexisting coronary heart disease, and diabetes were positively related to stroke incidence for men and women, whereas adjusted FEV1 (forced expiratory volume in 1 second) and height were negatively related. Cholesterol was not related to stroke. Glucose for nondiabetic subjects had a U-shaped relationship with stroke. Body mass index was not clearly related to stroke, although participants with the highest body mass index had the highest stroke rate. Former smokers had similar stroke rates to never-smokers. Tests between the associations of risk factors and stroke incidence revealed these were not statistically different from the associations with stroke mortality. Conclusions-The risk factors had a similar effect on stroke incidence as on stroke mortality. Epidemiological studies with information on stroke mortality are likely to give results applicable to stroke incidence.