[Association of obesity and other cardiovascular risk factors with stroke the Japan Arteriosclerosis Longitudinal Study--Existing Cohorts Combined (JALS-ECC)].

OBJECTIVE

To assess the relationship between metabolic risk factors and the incidence of stroke stratified by obesity, by conducting a meta-analysis using individual participant data from prospective cohort studies.

METHODS

A total of 19,173 individuals from 10 cohort studies participated at baseline after 1985. Metabolic risk factors were defined using the established criteria in Japan. Participants were subdivided into five categories according to the levels of risk factors and obesity defined by BMI > or = 25 (kg/m2). Multivariate adjusted hazard ratios (HRs) for the incidence of stroke and the population attributable risk (PAR) were estimated by Poisson regression.

RESULTS

During an average 7.1-year follow-up period, 374 stroke events occurred. Hypertension was highest among the risk factors not concerned with BMI stratification. The HR for stroke was 2.48 (95% CI: 1.75-3.5) for BMI < 25 with 1 other risk factor and 3.75 (2.58-5.45) with 2 or more, 2.38 while it was (1.58-3.59) for BMI > or = 25 with 0 or 1 factor and 3.26 (2.11-5.02) with 2 or more. The HR was significantly elevated in all categories with one or more risk factors. The PAR was highest in the category of BMI < 25 with 1 risk factor (23.3%) and second highest in the category of BMI < 25 with 2 or more. The respective PARs for BMI > or = 25 with 0 or 1 and 2 or more risk factors were 8.1% and 8.0%. Similar results were found from the analyses of different stroke subtypes.

CONCLUSIONS

The HR was found to be significantly elevated with the number of risk factors both with and without obesity. The attributable risk for stroke was larger in the non-obese group. Therefore, public health intervention based only on obesity may miss many of those at high risk of stroke so the focus should not only be on obesity but also cardiovascular risk factors.