Cost effectiveness of human immunodeficiency virus postexposure prophylaxis for healthcare workers

Objective: The United States Public Health Service (USPHS) published recomm endations for human immunodeficiency virus (HIV) postexposure prophylaxis ( PEP) of healthcare workers in May 1998. The aim of this study was to analys e the cost effectiveness of the USPHS PEP guidelines. Design and setting: This was a modelling study in the setting of the US hea lthcare system in 1998. The analysis was performed from the societal perspe ctive; however, only HIV healthcare costs were considered and health-relate d losses of productivity were not included. Methods: a decision tree incorporating a Markov model was created for 4 PEP strategies: the current USPHS recommendations, triple drug therapy, zidovu dine monotherapy or no prophylaxis. A probabilistic sensitivity analysis us ing a Monte Carlo simulation was performed. Confidence intervals (CIs) arou nd cost-effectiveness estimates were estimated by a bootstrapping method. Results: The costs (in 1997 US dollars) per quality-adjusted life-year (QAL Y) saved by each strategy were as follows: monotherapy $US688 (95% CI: $US6 24 to $US750); USPHS recommendations $US5211 (95% CI: $US5126 to $US5293): and triple drug therapy $US8827 (95% CI: $US8715 to $US8940). The marginal cost per year of life saved was: USPHS recommendations $US81 987 (95% CI: $ US80 437 to $US83 689); triple drug therapy $US970 451 (95% CI: $US924 786 to $US 1 014 429). Sensitivity testing showed that estimates of the probabi lity of seroconversion for each category of exposure were most influential, but did not change the order of strategies in the baseline analysis. With the prolonged HIV stage durations and increased costs associated with recen t innovations in HIV therapy, the marginal cost effectiveness of the USPHS PEP strategy was decreased to $US62 497/QALY saved. All 3 intervention stra tegies were cost effective compared with no postexposure prophylaxis. Conclusions: Current USPHS PEP recommendations are marginally cost effectiv e compared with monotherapy, but the additional efficacy of triple drug the rapy for all risk categories is rewarded by only a small reduction in HIV i nfections at great expense. For the foreseeable future, assuming innovation s in therapy that employ expensive drug combinations earlier in the HIV dis ease course to extend life expectancy and the increasing prevalence of HIV drug resistance, our model supports the use of the USPHS PEP guidelines.