Living Conditions, Low Socioeconomic Position, and Mortality in the Ibadan Study of Aging

Very little is known about socioeconomic differentials in mortality among persons surviving to old age in sub-Saharan Africa. We report on the impact of low socioeconomic position (SEP) on mortality over a 5-year observation period among community-dwelling older adults living in southwestern Nigeria. Data are from a household multistage probability sample of 2,149 Yoruba Nigerians aged 65 years or older. We collected information on indices related to health and well-being at baseline (2003/2004). Socioeconomic positions were estimated using asset-based measures relevant to low income settings. Information on mortality was obtained by research supervisors in multiple waves (2007, 2008, and 2009). Associations between baseline covariates and mortality were explored using discrete time survival models and life tables. We recorded 357 deaths over 5 years, or an annual mortality rate of 4.7% (95% CI = 4.2-5.2). Being 80 years or older (HR = 1.6, 95% CI = 1.1-2.5) and belonging to the lowest SEP (HR = 1.5, 95% CI = 1.1-2.1) were the main predictors of mortality. The significant effect of lowest SEP on mortality risk over the study period was independent of age, gender, education, rural or urban residence, weight, physical activity level, and social engagement. In this sample of older persons living in an economically disadvantaged context, we found persistent socioeconomic differentials in mortality estimated, conservatively, over 5 years.