Obesity and 10-Year Mortality in Very Old African Americans and Yoruba-Nigerians: Exploring the Obesity Paradox

Background. To compare the effect of obesity and related risk factors on 10-year mortality in two cohorts of older adults of African descent; one from the United States and one from Nigeria. Methods. Study participants were community residents aged 70 or older of African descent living in Indianapolis, Indiana (N = 1,269) or Ibadan, Nigeria (1,197). We compared survival curves between the two cohorts by obesity class and estimated the effect of obesity class on mortality in Cox proportional hazards models controlling for age, gender, alcohol use, and smoking history, and the cardiometabolic biomarkers blood pressure, triglycerides, high-density lipoprotein, low-density lipoprotein, and C-reactive protein. Results. We found that underweight was associated with an increased risk of death in both the Yoruba (hazards ratio = 1.35, 95% confidence interval: 1.12-1.63) and African American samples (hazards ratio = 2.49, 95% confidence interval: 1.40-4.43) compared with those with normal weight. The overweight and obese participants in both cohorts experienced survival similar to the normal weight participants. Controlling for cardiometabolic biomarkers had little effect on the obesity-specific hazard ratios in either cohort. Conclusions. Despite significant differences across these two cohorts in terms of obesity and biomarker levels, overall 10-year survival and obesity class-specific survival were remarkably similar.