PARAMETERISATION OF EXPECTED RESIDUAL LIFETIME AFTER SEROCONVERSION IN A UGANDAN SAMPLE POPULATION

Abstract

The consequences of the HIV/AIDS epidemic in Africa are expected to be considerable. A great deal of what is presently known about the HIV/AIDS epidemic has originated from studies in Europe or the Americas, or from urban African contexts. In contrast, the majority of people in sub-Saharan Africa infected with the virus will live in rural communities. It is important that demographic information be obtained for this rural African environment. This contribution is aimed at investigation and verification of HIV-1 mortality patterns in a rural African context. The authors examine eight years of incident HIV mortality data arising from the Masaka district in Uganda. These data are bivariate and of a type termed doubly censored. The authors explore the non-parametric procedures required for estimation of self-consistent patterns using doubly censored data. Information on age and gender is also incorporated into the analyses. The results are parameterised using a range of survival probability models. The Gompertz probability model provides a reasonable emulation of eight years of empirical underlying hazard, over all age classes, and can be considered as a reasonable first approximation to the HIV/AIDS mortality model for the phenomenon and context of this study. The results also indicate that expected time to death at seroconversion is appreciably affected by age at seroconversion. Extrapolation of these mortality patterns into the future will, however, necessarily remain unsubstantiated until further data become available and the ability to generalise these findings to other contexts remains a subject worthy of further study.