Low versus High CD4 Cell Count as Starting Point for Introduction of Antiretroviral Treatment in Resource-Poor Settings: A Scenario-Based Analysis

Abstract

Objective

To evaluate CD4 cell count-driven strategies for the initiation of highly active antiretroviral therapy (HAART) in terms of the reduction of the incidence of AIDS-defining events in resource-poor settings.

Methods

Data from the Amsterdam Cohort Study on HIV infection and AIDS were used to estimate the hazard of AIDS in untreated HIV-1 infection and after initiation of HAART, respectively, conditional on CD4 cell count. Different strategies for initiating therapy were compared by calculating the expected HAART administration rate and 1-year cumulative AIDS incidence in three different population settings, varying in the stage of HIV-1 infection at the time of presentation.

Results

Among 695 HIV-1-infected cohort participants, the 1-year AIDS incidence density (ID) ranged from 3.2 per 100 person-years for CD4 cell counts 600–700 cells/mm³, to 31.9 per 100 person-years for CD4 cell counts 100–200 cells/mm³ and 77.9 per 100 person-years for CD4 cell counts below 100 cells/mm³. Upon initiation of HAART, the ID in the lowest CD4 strata declined to 13.3 and 16.3 per 100 person-years, respectively. Extrapolated to developing countries, supply of HAART to patients presenting with HIV-1 infection below 200 CD4 cells/mm³ is expected to give an administration rate of 67%, while the AIDS incidence will drop from over 30% to almost 10%.

Conclusions

Introduction of HAART in populations with advanced HIV-1 infection can accomplish a threefold reduction of the AIDS incidence when HAART is administered to patients with CD4 cell counts below 200 cells/mm³. In a hospital-based setting in resource-poor environments this ensures an efficient treatment allocation.