Clustering of child and adult mortality during pre and post ART rollout eras at Agincourt and Dikgale health and demographic surveillance systems in South Africa
Ndebele, Sikhuphukile Gillian
The effect of anti-retroviral therapy (ART) rollout can be measured in a number of ways including treatment coverage, behaviour change and the emergence of resistance. However, changes in population mortality are undoubtedly the most important measurable effect. Objectives: To describe trends in child and adult all-cause mortality versus HIV/AIDS related mortality before and after ART rollout; and to identify significant clusters of child and adult all-cause mortality versus HIV/AIDS related mortality in space-time, during pre and post ART rollout eras at Agincourt and Dikgale health and demographic surveillance systems (HDSSs) in South Africa. Design: Mortality data were extracted from both the Agincourt and Dikgale HDSSs for the period 1996–2010. Mortality rates by age group, year and village were calculated assuming a Poisson distribution and using precise person-years as the denominator. The Kulldorff spatial scan statistic was used to test for clusters of age group all-cause and HIV-related mortality both in space and time. Clusters were mapped using Quantum geographic information systems (GIS) software. Results: Both HIV-related and all-cause mortality decreased gradually over the years after the introduction of ART in 2007 for the two HDSS sites. Several statistically significant clusters of higher all-cause and HIV-related mortality were identified both in space and time. In the Agincourt HDSS, specific areas were consistently identified as high risk areas; namely, the east/south-east corner and upper central to west regions, pre ART. In the Dikgale HDSS, no significant clusters were identified using the spatial only analysis but one significant cluster, located towards the north of the Dikgale HDSS site, was identified using the space-time scanning, post ART. In Agincourt, no significant clusters of mortality were detected after the introduction of ART whereas in Dikgale, a significant cluster for all-cause mortality in the under-five age group was detected for the years after the introduction of ART. Conclusion: This work revealed the existence of spatio-temporal clusters of both child and adult mortality at the Agincourt and Dikgale HDSSs and that the introduction of ART had a substantial influence in reducing both HIV-related and all-cause mortality in rural South Africa. There is need though to take into account socio-demographic characteristics so as to determine fundamental risk factors influencing these spatio-temporal HIV-related and all-cause mortality patterns.