BACKGROUND: A key element for payers in the assessment of the economic profile of a medication is its anticipated impact on the evolution of healthcare budgets. OBJECTIVES: To forecast the impact of the use of darunavir with low-dose ritonavir 600/100 mg twice a day (bid) in highly treatment-experienced, HIV-infected adults who have failed one or more protease inhibitor (PI)-containing regimen on the budget of the French Sickness Fund (French healthcare system) over a 3-year time horizon. METHODS: A transition state model based on disease severity was developed that compared the evolution of antiretroviral and non-antiretroviral-related direct costs of care in the target population over 3 years (2007-2009) under two scenarios: (1) darunavir enters the French market in year 1+ADs- (2) darunavir is not available to the target population during 2007-2009. Model inputs were derived from a targeted analysis of the French hospital database in HIV, the darunavir POWER 1 and 2 trials and other relevant clinical studies. RESULTS: In the scenario where darunavir was available from year 1, the proportion of patients in the lower, more costly CD4 cell count strata (+ADw-/+AD0- 100 cells per mm(3)) was consistently lower than in the scenario without darunavir in each year of the model (17.0+ACU- vs 19.2+ACU-, 13.9+ACU- vs 18.3+ACU- and 10.8+ACU- vs 16.8+ACU- for years 1, 2 and 3, respectively). As a result, over the entire 3-year period, the net increase of antiretroviral drug costs ( 5.6 million Euros+ADs- euro), resulting from the substitution of older, cheaper PIs by darunavir, is expected to be fully compensated by savings in hospitalization costs (euro-9.7 million) and expenditures for other HIV-related (non-antiretroviral) medications (euro-7.3 million), leading to a net saving of euro11.4 million or 2.9+ACU- of the total budget in the scenario without darunavir. Various sensitivity analyses confirmed these projected savings. CONCLUSION: The use of darunavir/ritonavir (DRV/r) 600/100 mg bid, in combination with other antiretroviral agents, in highly pre-treated, HIV-infected adults who have failed one or more PI-containing highly active antiretroviral therapy regimen is not expected to increase the budget of the French healthcare system, in comparison with a scenario without darunavir. Further research is needed to estimate the budget impact of the use of DRV/r in less treatment-experienced, HIV-infected individuals in France
