A total of 79% of individuals prescribed post-exposure prophylaxis (PEP) after a possible sexual exposure to HIV fully adhered to their 28 day course of antiretroviral therapy, according to a French study published in the January 9th edition of AIDS. The investigators, from Paris, found that individuals of African origin who sought PEP, and people requesting treatment after oral sex, were significantly less likely to complete their four weeks of antiretroviral treatment.
PEP for sexual exposure to HIV is being made increasing available. There are concerns, however, that individuals requesting PEP do not always take the recommended four weeks of treatment. In addition, the growing number of people requesting PEP is placing a mounting strain on healthcare budgets meaning that evidence of the cost-effectiveness of PEP is required to justify its provision.
Doctors in Paris conducted a study designed to show why people provided with PEP for possible sexual exposure to HIV either did or did not take their treatment. A doctor saw individuals on the day they were provided with treatment and again after the 28 days of treatment were completed. Socio-demographic data were obtained on the day PEP was provided and an HIV test was performed three months after treatment was first prescribed. An individual was defined as being adherent if he or she took all 28 days of treatment.
The study population consisted of 137 individuals, 100 of whom knew that they were HIV-negative before requesting PEP. Most people (89%) requested PEP after sex with a casual partner, 50% after anal sex, and 54% claimed that they needed PEP as a result of a condom accident. Sex between men was reported by 61% of individuals and 5% were African. A quarter of sexual partners were known to be HIV-positive.
PEP was provided within 48 hours of possible exposure to 124 individuals, with 73 people requesting treatment within four to 24 hours of their sexual encounter. In 127 cases, triple antiretroviral therapy consisting of AZT (zidovudine, Retrovir), 3TC (lamivudine, Epivir) and nelfinavir (Viracept) was provided, with the remaining ten patients taking dual therapy comprising AZT and 3TC.
It was established that 109 individuals (79%) took all 28 days of treatment. None of these people subsequently tested HIV-positive. The mean duration of treatment in the 28 people who stopped treatment early was twelve days. The investigators found that individuals of African ethnicity were over 13 times more likely to have incomplete adherence to PEP, and that people requesting PEP after a possible exposure to HIV due to oral sex were eight times more likely not to complete their full course of treatment.
Side-effects were widely reported and were consistent with the antiretroviral drugs provided. A total of 58 individuals reported diarrhoea, 38 nausea and 24 fatigue.
The investigators note that the 79% adherence rate seen in their study was well within the cost-effectiveness range. They also observed that individuals requesting PEP after unprotected anal sex, which involves the greatest potential risk of HIV transmission, were most likely to complete their course of treatment.
Commenting on the poorer adherence seen amongst African individuals, they refer to a South African study involving HIV-positive patients that found “adherence decreased with the fear of stigmatisation. Such behaviour may also be present in the African community living in France, and especially those exposed to HIV.”
Reference
Lacombe K et al. Determinants of adherence to non-occupational post HIV exposure prophylaxis. AIDS 20: 291 – 293, 2006.