Addressing inequality in health in sub-Saharan Africa through robust measurement of socio-economic status

Abstract

Socioeconomic status (SES) is an important determinant of the likelihood that individuals and populations are exposed to environmental and other risk factors for health. Both single and composite measures from census and administrative databases of local authorities have been used to define the socio-economic characteristics of an area in developed countries. The situation in Nigeria, like many other developing countries, is that demographic data at district level is scarce, while the methodologies for defining socio-economic groups are less developed. For a study of air pollution and respiratory health of school children in Warri, Nigeria, a purpose-designed measure of deprivation had to be devised, using data that could be gathered in the field. Data on socio-economic and material deprivation indicators were gathered through a surveillance exercise and interacting with residents of the study area on multiple visits. Low SES in the selected neighbourhood and schools were characterised by the metrics of sixteen indicators such as lack of electricity, no clean water, use of pit latrines, open drainage, untarred roads, living in a multi-tenant houses with metal roofing sheets, cooking with firewood or kerosene, high traffic density and densely populated areas. Other metrics such as access to metered electricity, living in a flat or bungalow with aluminium roofing sheet and water-closet, in a sparsely populated, low traffic density, planned neighbourhood with tarred road and closed drainage; availability of pipe-borne water and use of gas for cooking characterised affluent neighbourhood. Understanding the strengths and limitations of different indicators and the context is vital not only for designing the study, but also to interpret its results. Controlling for SES in the study design such as this, and/or statistical analysis is important in defining the extent of exposure disease association and, more importantly, to determine the size of health benefit achievable through feasible exposure reductions.