OBJECTIVES: Darunavir (TMC114; DRV) is a novel protease inhibitor (PI) with demonstrated superior efficacy to currently available PIs for the treatment of HIV infection in treatment experienced adults who have failed prior antiretroviral therapy. We evaluated the cost-effectiveness (CE), from a Canadian provincial Ministry of Health perspective, of ritonavir-boosted DRV (DRV/r) plus an optimized background regimen (OBR) compared to currently available PIs plus OBR (control).
METHODS: A Markov model with 3-month cycles was developed to follow patients through 6 possible health states defined by CD4 cell count ranges. Costs (in 2006 Canadian dollars) were assumed to accrue based on estimates of health care services used during each health state. Each health state also had an associated utility value. Cost, utility, and mortality data were estimated from published Canadian sources. Transition probabilities were calculated from clinical trials. Both costs and outcomes were discounted at 5%/year. Two analyses were conducted: 1) incremental cost/additional person with viral load <50 copies/mL at 48 weeks; 2) incremental lifetime cost/quality-adjusted life-year (QALY) gained. Extensive sensitivity and variability (assessing impact of practice patterns, population and model characteristics) analyses were performed.
RESULTS: DRV/r is associated with a 36% absolute increase in probability of achieving viral load <50 copies/mL at 48 weeks and a gain of 1.27 QALYs over a lifetime. The incremental cost/additional person with viral load <50 copies/mL was $9897; the incremental cost/QALY gained was $30,907. Sensitivity and variability analyses showed results were robust. For most of the credible uncertainty ranges, the CE ratio remained less than $50,000/QALY gained. Variability analyses showed CE ratios ranged $23,283–$34,667 depending most heavily on the assumed amount of tipranavir use in the model control arm and enfuvirtide use in the OBR.
CONCLUSION: When compared to current standard of care, DRV/r plus OBR is cost-effective in treatment-experienced adults who have failed prior antiretroviral therapy.
