Estimating treatment coverage in South African ART clinics based on the time trend of the CD4 count distribution at ART initiation and a dynamical epidemiological model

[摘要] ENGLISH ABSTRACT: HIV treatment coverage is currently inferred by dividing the number of peoplealive and on antiretroviral treatment (ART) by the number of individualseligible for treatment, and estimates of these numbers are often made usingdynamical epidemiological model. However, this approach ignores data on thedistribution of CD4 cell counts at the time of ART initiation, and hence the inferred treatment coverage may be inconsistent with these CD4 count data.Here, we present a more inclusive method to estimate treatment coverage byincorporating the time trend of the CD4 count distribution at ART initiationin the dynamic epidemiological model. Data analysis of a cohort of 61 398 HIVinfected adult patients who initiated treatment at eight South African ARTclinics between 2004-2009 was conducted. Next, we used the results of thestatistical analysis to adjust the parameters in the epidemiological model thatgoverns the rate at which people from different CD4 cell count levels initiateART. Lastly, we calibrate the model to reproduce the number of people aliveand on ART.More than 80% of individuals started treatment very late, with CD4 count<200 cells/ L. A maximum of three years were delayed treatment after beingeligible in all clinics involved in this study. The treatment coverage reached61% in the eight clinics in our study. Methods to estimate ART coverageshould make maximal use of CD4 cell count data at ART initiation, whichmay help to improve accuracy of the coverage estimates.

[发布机构] Stellenbosch University