Cost-Efffectiveness of Alternative Strategies to start Antiretroviral Therapy in Nigeria: A Model Analysis.

Abstract

The aim of this paper was to study the cost and health outcomes measured by Disability-Adjusted Life Years (DALYs) and cost-effectiveness of old and new methods with regard to the initiation of antiretroviral therapy in HIV/AIDS patients in Nigeria. Decision-analytic tree and Markov model were used to evaluate the clinical and economic consequences of the new WHO recommendations. Two arms of initiation evaluated were the deferred therapy arm (CD4<350clls/ml) and the immediate therapy arm (CD4 > 500cells/ml). Major outcome measures were DALYs averted, percentage DALY averted, costs from health payer’s perspective, Incremental cost and Incremental Cost-Effectiveness Ratio (ICER). The main input parameters were hazard rates from the Strategic Timing of Antiretroviral Treatment (START) trial and risk of sexual transmission of HIV, disability weights, adjustment rates, discount rates, life expectancy, and the annual cost of treatment, cost of clinical events, death and transmission. Deterministic and probabilistic sensitivity analyses (Monte Carlo simulations) were then executed. The immediate ART arm caused 0.595 DALY aversion compared with the delayed arm. This is equivalent to a 94% DALY aversion. It also caused a reduced financial burden of -$345.93. The incremental cost-effectiveness ratio was -$581.00 (dominant). This ICER was robust to both probabilistic and deterministic sensitivity analyses. For the Nigerian healthcare system, starting antiretroviral therapy in HIV/AIDs patients with CD4 count > 500cells/ml was found to be less costly and more effective than the old initiation strategies. The decision to adopt the new strategy by the Nigerian health policy makers is highly justified.