The epidemiology of HIV infection in Zambia

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Kandala, Ngianga-Bakwin ; Ji, Chen ; Cappuccio, Francesco ; Stones, R. Willliam (2008)

Abstract Population surveys of health and fertility are an important source of information about demographic trends and their likely impact on the HIV/AIDS epidemic. In contrast to groups sampled at health facilities they can provide nationally and regionally representative estimates of a range of variables. Data on HIV sero-status were collected in the 2001-2 Zambia Demographic and Health Survey (ZDHS) and made available in a separate data file in which HIV status was linked to a very limited set of demographic variables. We utilized this data set to examine associations between HIV prevalence, gender, age and geographical location by using the generalized geo-additive semi-parametric model as an alternative to the common linear model in HIV research. 54 % of the overall sample of 3950 was female. The overall HIV positivity rate was 565 (14.3%). The mean age at HIV diagnosis for male was 30.3 (SD: 11.2) and 27.7 (SD: 9.3) for female respectively. Lusaka and Copperbelt have the first and second highest prevalence of AIDS/HIV (marginal odds ratios of 3.24 and 2.88 respectively) but when the younger age of the urban population and the spatial auto-correlation was taken into account Lusaka and Copper belt were no longer among the areas with the highest prevalence. Nonlinear effects of age at HIV diagnosis were also discussed and the importance of spatial residual effects and control of confounders on the prevalence of HIV infection. Controlling for important risk factors such as geographical location, age structure of the population, gender gave estimates of prevalence that are statistically robust. Researchers should be encouraged to use all available information in the data to account for important risk factors when reporting AIDS/HIV prevalence. Where this is not possible, correction factors should be applied, particularly where estimates of AIDS/HIV prevalence are pooled in systematic reviews. Our maps can be used for policy planning and management of AIDS/HIV in Zambia. (Kandala, Ngianga-Bakwin) (Ji, Chen) (Cappuccio, Francesco P) (Stones, William) Warwick Medical School, Clinical Sciences Research Institute - Clifford Road Bridge--> , Walsgrave Hospital--> - CV2 2DX - Coventry - UNITED KINGDOM (Kandala, Ngianga-Bakwin) Warwick Medical School, Clinical Sciences Research Institute - Coventry - UNITED KINGDOM (Ji, Chen) Warwick Medical School, Clinical Sciences Research Institute - Coventry - UNITED KINGDOM (Cappuccio, Francesco P) University of Southampton, Centre for AIDS Research - Southampton - UNITED KINGDOM (Stones, William) UNITED KINGDOM
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