Changes in mortality patterns and associated socioeconomic differentials in a rural South African setting: findings from population surveillance in Agincourt, 1993-2013

Kabudula, Chodziwadziwa Whiteson
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Understanding a population’s mortality and disease patterns and their determinants is important for setting locally-relevant health and development priorities, identifying critical elements for strengthening of health systems, and determining the focus of health services and programmes. This thesis investigates changes in socioeconomic status (SES), cause composition of overall mortality and the socioeconomic patterning of mortality that occurred in a rural population in Agincourt, northeast South Africa over the period 1993-2013 using Health and Demographic Surveillance Systems (HDSS) data. It also assesses the feasibility of applying record linkage techniques to integrate data from HDSS and health facilities in order to enhance the utility of HDSS data for studying mortality and disease patterns and their determinants and implications in populations in resource-poor settings where vital registration systems are often weak. Results show a steady increase in the proportion of households that own assets associated with greater modern wealth and convergence towards the middle of the SES distribution over the period 2001-2013. However, improvements in SES were slower for poorer households and persistently varied by ethnicity with former Mozambican refugees being at a disadvantage. The population experienced steady and substantial increase in overall and communicable diseases related mortality from the mid-1990s to the mid-2000s, peaking around 2005-07 due to the HIV/AIDS epidemic. Overall mortality steadily declined afterwards following reduction in HIV/AIDS-related mortality due to the widespread introduction of free antiretroviral therapy (ART) available from public health facilities. By 2013, however, the cause of death distribution was yet to reach the levels it occupied in the early 1990s. Overall, the poorest individuals in the population experienced the highest mortality burden and HIV/AIDS and tuberculosis mortality persistently showed an inverse relation with SES throughout the period 2001-13. Although mortality from non-communicable diseases (NCDs) increased over time in both sexes and injuries were a prominent cause of death in males, neither of these causes of death showed consistent significant associations with household SES. A hybrid approach of deterministic followed by probabilistic record linkage, and the use of an extended set of conventional identifiers that included another household member’s first name yielded the best results for linking data from the Agincourt HDSS and health facilities with a sensitivity of 83.6% and a positive predictive value (PPV) of 95.1% for the best fully automated approach. In general, the findings highlight the need to identify the chronically poorest individuals and target them with interventions that can improve their SES and take them out of the vicious circle of poverty. The results also highlight the need for integrated health-care planning and programme delivery strategies to increase access to and uptake of HIV testing, linkage to care and ART, and prevention and treatment of NCDs especially among the poorest individuals to reduce the inequalities in cause-specific and overall mortality. The findings also contribute to the evidence base to inform further refinement and advancement of the health and epidemiological transition theory. Furthermore, the findings demonstrate the feasibility of linking HDSS data with data from health facilities which would facilitate population-based investigations on the e↵ect of socioeconomic disparities in the utilisation of healthcare services on mortality risk. Keywords Agincourt Cause of death composition Epidemiological Transition Health and Demographic Surveillance System (HDSS) Household assets HIV/AIDS Index of Inequality InterVA Mortality Non-communicable Diseases Population Surveillance Record linkage Rural Socioeconomic Status South Africa Verbal Autopsy Wealth Index
A thesis submitted to the Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy (by publications) 20th December 2017.