Cost and cost-effectiveness of switching from stavudine to tenofovir in first-line antiretroviral regimens in South Africa

Background: Most first-line antiretroviral therapy regimens in Africa include stavudine (d4T), despite the high incidence of toxicities related to it. We estimated. the cost and cost-effectiveness of switching from d4T to tenofovir disoproxil fumarate (TDF) in South Africa. Methods: A model was developed to estimate the proportion of patients in a hypothetical cohort who experienced d4T- and TDF-related events over the 2 years after antiretroviral therapy initiation. Transition probabilities, event and drug costs, and utility losses were estimated from primary data and the literature. Outcomes included incremental cost, incremental cost-effectiveness ratio per quality-adjusted life year gained, and threshold prices for TDE Results: After 2 years, 82.5% of the d4T scenario cohort remained on d4T, 16.6% had switched to AZT, 0.8% had died, and 414 events that did not lead to a drug change had occurred. In the TDF scenario, 97.5% of the cohort remained on TDE At a baseline cost of TDF of $17.00/month. the incremental cost of the TDF scenario was $128/patient/year and the incremental cost-effectiveness ratio was $9007 per quality-adjusted life year gained. The change to TDF would be cost neutral for the government at a price of $6.17/month and highly cost effective at a price of $12.94/month., Conclusions: At a TDF price of $17.00/month, savings on d4T toxicity management will offset roughly 20% of the higher price of TDE The price of TDF would have to fall substantially to make the change cost neutral for South Africa in budgetary terms, but it would be highly cost effective at a price only slightly less than what is currently available.