J-3 A COST-EFFECTIVENESS ANALYSIS OF GENOTYPE DRUG RESISTANCE TESTING AT FAILURE OF 1ST-LINE ANTIRETROVIRAL THERAPY IN HIV-INFECTED PATIENTS IN SOUTH AFRICA

Tuesday, October 26, 2010: 1:30 PM
Grand Ballroom Centre (Sheraton Centre Toronto Hotel)
Julie Levison, MD, MPHIL1, Robin Wood, FCP, MMed, DTM&H2, Callie Scott, MSc3, Andrea Ciaranello, MD, MPH3, Elena Losina, PhD1, Kenneth A. Freedberg, MD, MSc3 and Rochelle P. Walensky, MD, MPH3, (1)Massachusetts General Hospital and Brigham and Women's Hospitals, Boston, MA, (2)University of Cape Town, Cape Town, South Africa, (3)Massachusetts General Hospital, Boston, MA

Purpose:   In resource-limited settings, antiretroviral treatment (ART) options are limited. At 1st-line ART failure, genotype drug resistance testing can identify patients with non-resistant (wild-type) virus who have failed due to poor medication adherence. These patients may safely and effectively continue 1st-line ART, avoiding premature switches to costlier 2nd-line ART.

Methods:   We used a state-transition, Monte Carlo simulation of HIV disease and treatment (the CEPAC-International model) to project per-person life expectancy (LE) and mean lifetime HIV care costs (2006 US$) for no genotype vs. genotype strategies at 1st-line ART failure. In the no genotype strategy, all patients switched to 2nd-line ART at diagnosis of 1st-line ART failure. In the genotype strategy, patients with wild-type virus remained on 1st-line ART with an adherence intervention, and those with resistant virus switched to 2nd-line ART. Model inputs were derived using clinical and cost data from South Africa (mean age 32.8y, mean CD4 307/µl, genotype cost $300/test, 1st-line ART $7/month, 2nd-line ART $63/month); 20% of patients had wild-type virus at 1st-line ART failure. A strategy was considered “very cost-effective” if  the incremental cost-effectiveness ratio (ICER) was below the 2006 South African per capita gross domestic product ($5,400/year of life saved [YLS]). In sensitivity analyses, we examined the impact of variations in prevalence of drug resistance at 1st-line ART failure, ART efficacies, and both genotype and ART costs.

Results: At 1st-line ART failure, projected LE with no genotype was 152.4 months and increased to 155.9 months with genotype. Per-person lifetime costs were $11,690 and $11,740, respectively.  Compared to no genotype, the ICER for genotype was $160/YLS. Genotype was very cost-effective under plausible variations in efficacies of 1st- and 2nd-line ART. In a 2-way sensitivity analysis, genotype was very cost-effective at the base case test cost ($300), if prevalence of wild-type virus remained >2% (Figure, circle). At the base case prevalence of wild-type virus (20%), genotype was very cost-effective at test costs <$2,600 (Figure, square); at 20% wild-type prevalence, results were not sensitive to the genotype cost since this was offset by the savings in 2nd-line ART costs.
                           

[Figure. Incremental cost-effectiveness ratio (ICER, 2006 USD/YLS) of genotype vs. no genotype strategy].  

Conclusion: In South Africa, drug resistance testing at 1st-line ART failure increases the survival benefits of HIV treatment and is very cost-effective.  

Candidate for the Lee B. Lusted Student Prize Competition