Sex and ethnic‐origin specific BMI cut points improve prediction of 40‐year mortality: the Israel GOH study

BACKGROUND: Although obesity has been associated with a higher risk for premature death, the sex and ethnic-origin specific body mass index (BMI) levels that are associated with increased mortality are controversial. We investigated the 40-year cumulative all-cause mortality, in relation to the BMI in adult life, among men and women originating from Yemen, Europe/America, Middle East and North Africa, using sex and ethnic-origin specific BMI cut points. METHODS: A random stratified cohort (n = 5710) was sampled from the central population registry and followed since 1969 for vital status. Weight, height and blood pressure were measured, and smoking status was recorded at baseline. BMI was analysed according to conventional categories and according to sex and ethnic-origin specific quintiles. RESULTS: Elevated and significant mortality hazard ratios (HRs) of 1.21 [95% confidence interval (CI) 1.00-1.45] for women and 1.22 (95%CI 1.03-1.44) for men were found for the highest origin-specific BMI quintile. In men, the lowest ethnic-origin specific quintile was also significantly associated with increased mortality (HR of 1.22 95% CI 1.03-1.45), adjusting for age, smoking and blood pressure. Obesity was associated with mortality in non-smokers (HR = 1.29, 95% CI 1.04-1.61 in men and HR = 1.46, 95% CI 1.19-1.79 in women), whereas leanness was associated with mortality only among smoking men (HR = 1.39, 95% CI 1.09-1.77). CONCLUSION: Refinement of BMI categories using country of origin specific quintiles demonstrated significantly increased mortality in the upper quintile in both sexes, while according to the conventional values this association did not prevail in men. We propose the establishment of sex and origin-specific BMI categories when setting goals for disease prevention.