Public health
 français
 

HIV postexposure prophylaxis: new recommendations

Canadian Medical Association Journal 1997; 156: 233

© 1997 Canadian Medical Association

See also:
Although the average risk of acquiring HIV infection after percutaneous exposure to HIV-infected blood is only 0.3%,[1] health care workers welcomed the news that postexposure prophylaxis with zidovudine (AZT) can reduce this risk by as much as 79.0%.[2] Recommendations from the US Centers for Disease Control and Prevention (CDC)[3] have been revised to take into account the potential for greater benefit from combination drug treatment, especially after massive exposure or when drug resistance is a possibility (Table 1).

Postexposure assessment should take into account the nature of the exposure, the likelihood of HIV infection in the source patient and, in cases of known infection, the HIV titre and likelihood of drug resistance. Appropriate counselling for the exposed worker is crucial, and the risk of infection should be weighed against the potential toxicity of antiretroviral agents. When given, prophylaxis should be started within 1 or 2 hours after the exposure and continue for 4 weeks.

The advice of an expert in antiretroviral therapy should be sought when drug resistance is possible. Prophylactic AZT in the recommended dose is well tolerated, but higher doses may cause gastrointestinal symptoms, fatigue and headache. Given in the second or third trimester of pregnancy, it has been associated with mild reversible anemia in the infant but not with adverse effects in the mother. Its use in the first trimester has received only limited study.[3] The toxicity of prophylactic 3TC and IDV is uncertain, and the safety of these drugs for use during pregnancy has not been established.

The extrapolation of guidelines for postexposure prophylaxis to other situations such as sexual assault is being considered at some centres. Like the use of combination therapy advocated by the CDC, such extensions are based on sound science but are difficult to test objectively. It is likely that well-crafted guidelines will reduce the risk of HIV infection among health care workers and others. Such guidelines must be applied intelligently to avoid waste, needless side effects and the diversion of the drug supply away from more clearly beneficial applications. Physicians should remain alert to recommendations as they evolve and ensure that the necessary drugs are at hand.

David M. Patrick, MD
British Columbia Centre for Disease Control
Vancouver, BC

References

  1. Tokars JI, Marcus R, Culver DH, Schable CA, McKibben PS, Bandea CI, et al, for the CDC Cooperative Needlestick Surveillance Group. Surveillance of HIV infection and zidovudine use among health care workers after occupational exposure to HIV-infected blood. Ann Intern Med 1993;118:913-9.
  2. Case­control study of HIV seroconversion in health-care workers after percutaneous exposure to HIV-infected blood -- France, United Kingdom, and United States, January 1988­August 1994. MMWR 1995;44:929-33.
  3. Update: provisional public health service recommendations for chemoprophylaxis after occupational exposure to HIV. MMWR 1996;45:468-72.
| CMAJ January 15, 1997 (vol 156, no 2) |