Health literacy assessment in developing countries: a case study in Zambia.

Education and literacy are key determinants of health but do not necessarily ensure health literacy (HL). The Institute of Medicine's (IOM) definition of HL is widely accepted, but there is no consensus over its constituent parts. Developing a practical measure of HL is a priority, but challenging. We aimed to derive a measure of HL in data from the Demographic and Health Surveys (DHS) Program administered by the United States Agency for International Development (USAID), which includes items representing domains of HL as defined by the IOM. We accessed data from the DHS conducted in Zambia in 2007. We applied factor analysis methods to eight survey questions that corresponded to elements of the IOM definition. We derived a single indicator and evaluated for reliability and validity. The derived dichotomous measure of HL demonstrated reliability (Cronbach's α = 0.68), good content validity, and importantly was composed of the elements described by the IOM including capacity to obtain, interpret and understand health information, and make appropriate health decisions. Only 46.5% of males and 24.5% of females had high literacy. HL varied considerably across other subgroups. This is the first study to derive a robust indicator of HL following the IOM definition in a large national sample. By applying and evaluating this method in future studies, researchers can use this approach in other DHS datasets to measure HL in additional countries, and ultimately test how HL relates to health outcomes.