Prophylaxis of HIV infection following occupational exposure

OBJECTIVE: To review the risk of HIV infection following occupational exposure, the theoretical basis for chemoprophylaxis, investigative experience with chemoprophylaxis in animals and humans, and the economic aspects of postexposure chemoprophylaxis. DATA SOURCES: English-language articles and conference proceedings pertaining to the risk of occupational HIV infection and to postexposure chemoprophylaxis. STUDY SELECTION: Studies evaluating chemoprophylaxis of HIV infection following occupational exposure were selected for review. Abstracts reporting ongoing clinical trials were also included. DATA EXTRACTION: In vitro studies are discussed to provide the immunologic rationale for chemoprophylaxis. Animal studies examining the efficacy of chemoprophylaxis in preventing non-HIV retroviral infection are reviewed, and their applicability to human HIV infection is critically evaluated. Human studies and case reports describing attempts at chemoprophylaxis of HIV infection following occupational exposure are discussed. DATA SYNTHESIS: Chemoprophylaxis of HIV infection following occupational exposure has focused on the use of zidovudine (ZDV) because it was previously the only antiretroviral agent approved for treating HIV infection. Animal models of retroviral infection provide conflicting data regarding the efficacy of ZDV chemoprophylaxis, and there are important questions about the applicability of animal data to human HIV infection because of differences in natural histories of non-HIV retroviral infections, inoculum size, dosing of ZDV, and routes of infection. Human surveillance studies are thus far inadequate to determine the efficacy of ZDV prophylaxis because of the very low HIV seroconversion rates following occupational exposure. ZDV is well tolerated during short-term administration in people without HIV infection, but long-term safety is unknown. In addition, the true cost-benefit ratio of ZDV chemoprophylaxis is uncertain. CONCLUSIONS: Current data from in vitro, animal, and human studies are inadequate to define the appropriate role of ZDV in preventing HIV infection following occupational exposure. Limited toxicity data and the high cost of treatment must be weighed against the theoretical benefits of ZDV use in this setting. The decision to employ ZDV for postexposure prophylaxis must ultimately be based on existing institutional policies, the attitude of the responsible physician regarding such practice, and/or the desires of the exposed healthcare worker after being properly informed of potential risks and benefits.