COST-EFFECTIVENESS OF CHEMOPROPHYLAXIS AFTER OCCUPATIONAL EXPOSURE TOHIV

Objectives: To assess the economic efficiency of recent US Public Heal th Service recommendations for chemoprophylaxis with a combination of antiretroviral drugs following high-risk occupational exposure to huma n immunodeficiency virus (HIV). To provide a framework for evaluating the relative effectiveness and costs associated with candidate postexp osure prophylaxis (PEP) regimens. Methods: Standard techniques of cost -effectiveness and cost-utility analysis were used. The analysis compa res the costs and consequences of a hypothetical, voluntary combinatio n-drug PEP program consisting of counseling for all HIV-exposed health care workers, followed by chemoprophylaxis for those who elect it vs an alternative in which PEP is not offered. A societal perspective was adopted and a 5% discount rate was used. Hospital costs of recommende d treatment regimens (zidovudine alone or in combination with lamivudi ne and indinavir) were used, following the dosing schedules recommende d by the US Public Health Service. Estimates of lifetime treatment cos ts for Hn; and acquired immunodeficiency syndrome were obtained from t he literature. Because the effectiveness of combination PEP has not be en established, the effectiveness of zidovudine PEP was used in the ba se-case analyses. Main Outcome Measures: Net PEP program costs, number of HIV infections averted, cost per HIV infection averted, and cost-u tility ratio (net cost per discounted quality-adjusted life-year saved ) for zidovudine, lamivudine, and indinavir combination PEP. Lower bou nds on the effectiveness required for combination regimens to be consi dered incrementally cost saving, relative to zidovudine PEP alone, wer e calculated. Multiple sensitivity and threshold analyses were perform ed to assess the impact of uncertainty in kelt parameters. Results: Un der base-case assumptions, the net cost of a combination PEP program F or a hypothetical cohort of 10 000 HIV-exposed health care workers is about $4.8 million. Nearly 18 HIV infections are prevented. The net co st per averted infection is just less than $400 000, which exceeds est imated lifetime HIV and acquired immunodeficiency syndrome treatment c osts, Although combination PEP is not cost saving, the cost-utility ra tio (about $37 000 per quality-adjusted life-year in the base case) is within the range conventionally considered cost-effective, provided t hat chemoprophylaxis is delivered in accordance with Public Health Ser vice guidelines. Small incremental improvements in the effectiveness o f PEP are associated with large overall societal savings. Conclusions: Under most reasonable assumptions, chemoprophylaxis with zidovudine, lamivudine, and indinavir following moderate-to high-risk occupational exposures is cost-effective for society, If combination PEP is minima lly more effective than zidovudine PEP, then the added expense of incl uding lamivudine and indinavir in the drug regimen is clearly justifie d.