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Kim Best, Senior Science Editor, Family Health International, Research Triangle Park, NC, USA Antiretroviral treatment of rape victims definitely or probably exposed to HIV during their assaults can be cost-effective in countries with high HIV prevalence. It also may be affordable in a middle-income country like South Africa, a modelling study conducted there suggests.1 However, the cost-effectiveness of such treatment, called post-exposure prophylaxis (PEP), is critically dependent upon improving sexual services and providing an environment that both encourages rape victims to seek care in a timely manner and complete their PEP regimen. PEP has been available through the South African public health system since 2002. In 2002-2003, nearly 55 000 rapes and attempted rapes were reported in South Africa, although the actual rate may be substantially greater. With 14-28% of rapists in South Africa estimated to be HIV-infected, their victims face considerable infection risks. Providing all rape victims with PEP may be substantially less costly than later treating only those who become infected, the study researchers from the South African Medical Research Council and the University of Witwatersrand estimated. In South Africa, the difference could be as great as US$ 2000 per person. In the modelling exercise, researchers made several assumptions. First, they assumed that the use of PEP after rape would be at least 80% effective. This reflects results from a retrospective case-control study indicating that the odds of HIV infection were reduced by about 81% among healthcare workers who took PEP after exposure to HIV via needlestick injuries.2 Although the efficacy of occupational PEP has not been definitively proved and failure of PEP to prevent HIV infection has been reported, a substantial body of other research also supports the effectiveness of PEP after occupational exposures to HIV in healthcare settings. PEP has become the standard of care in such settings, and the United States has national guidelines for occupational PEP.3 Sexual and other nonoccupational exposure to HIV Limited data exist about PEP's effectiveness when given after sexual exposure to HIV. A small Brazilian study among homosexual men exposed to HIV found that PEP reduced seroconversion by 83%.4 Otherwise, efficacy has been largely assumed on the basis of animal and human data including occupational, perinatal, and non-occupational exposures to HIV. Several European nations, Australia, and several US states -- including California, New York, Massachusetts, and Rhode Island (see Resources) -- have issued guidelines for the use of PEP after sexual or other forms of non-occupational exposure to HIV. Until 2005, the US Centers for Disease Control and Prevention (CDC) had not recommended for or against the use of PEP after non-occupational exposure to HIV because it lacked information on PEP's effectiveness at curbing infection. But in January 2005, after considering recent animal and lab studies, the CDC began recommending a 28-day course of antiretroviral therapy for persons seeking care within 72 hours after non-occupational exposure to blood, genital secretions, or other potentially infectious body fluids of a person known to be HIV-infected,* when that exposure represents a substantial risk of infection.5 Nevertheless, the question of how to determine whether the risks of HIV infection justify use of PEP remains. Most exposures to HIV will not result in infection. In the case of sexual assault, considerations include the infectiousness of the rapist (e.g., viral loads are higher in recently seroconverted individuals) and the risk of infection based on the victim's age. For biological reasons, younger women are more susceptible. (Notably, the scientists who conducted the study in South Africa estimated that women under age 18 years had twice the risk of infection than did adult women.) Also to be considered is the degree of vaginal trauma and abrasions caused by rape. Risk of HIV infection after unforced vaginal intercourse with an infected man has been estimated to be 0.1-0.2% per act,6 but traumatic, forced sex could quadruple that risk, the researchers estimated. This heightened risk approximates that associated with occupational needlestick exposure, which has been estimated to be about 0.3%.7 Treatment regimens Even when HIV risk is clearly high and thus use of PEP seems most appropriate, type of treatment and compliance to treatment regimens need to be considered. PEP involves taking a brief course (usually 28 days) of antiretroviral medications as soon as possible after exposure, preferably beginning within 36 hours. While there is no evidence that any particular medication or combination of medications is best for PEP, certain regimens are preferred, including:
A two-drug regimen (i.e., a combination of two reverse transcriptase inhibitors) can be considered if clinicians or patients are worried about potential toxicity of, or difficulty complying with, a three-drug antiretroviral drug regimen. In fact, the three-drug regimen is preferred in order to maximise suppression of viral replication, based on the assumption that this will help prevent infection in the exposed person.8 The potential benefits of PEP must be carefully weighed against its potential dangers. All approved antiretroviral drugs have substantial drug interactions and adverse side-effects that are occasionally serious. For this reason, PEP is not justified for exposures posing a negligible risk for HIV infection. (Regardless of HIV risk, nevirapine is not recommended for PEP for safety reasons).9 The health risks associated with PEP are of particular concern when treatment is considered for adolescents or children, and great care must be taken in its administration.10 Treatment compliance Among the factors that the South African researchers considered in their PEP cost-effectiveness model was that of treatment compliance, which can be poor. Analysis of a registry of some 450 US healthcare workers who received PEP (often consisting of at least three antiretroviral drugs) after exposure to HIV found that nearly half of the workers discontinued all drugs and another 13% modified their drug regimen, commonly in response to adverse sideeffects.11 Even with support and counselling of patients, discontinuation of PEP can be high. Because a two-drug regimen is likely to be less costly, less toxic, have fewer side-effects, and be better tolerated than a three-drug regimen, it may be less frequently discontinued and may actually result in lower HIV transmission rates. In a study of PEP that primarily involved two reverse transcriptase inhibitors, 78% of some 400 individuals treated for 4 weeks completed treatment.12 A multidisciplinary team approach to PEP provision for rape victims, however, may increase adherence even to the three-drug regimen. Although evidence-based guidelines are needed, essential services suggested for rape victims receiving PEP include HIV testing for at least 6 months after exposure; counselling about the importance of completing the drug regimen, possible drug interactions and side effects, and how to minimise side-effects and recognise serious side-effects; and medical evaluation for toxicity at baseline and again 2 weeks after starting PEP. Integration of PEP with other services In middle- and low-income countries, particularly those with generalised HIV epidemics, research is urgently needed on how PEP can be included in patient care. But, in South Africa, the researchers who found PEP for rape victims to be cost-effective conducted additional research to explore how women themselves want PEP to be delivered.13 Interviews with 292 women, 159 of whom had accessed sexual assault services, indicated that they preferred PEP to be offered with other related sexual assault services. Such services included provision of HIV testing before PEP begins and having a sensitive healthcare provider conduct counselling. In fact, women who had been raped were willing to travel further to obtain such services, which better met their needs. Compliance to the PEP regimen might be improved, the researchers also concluded, by providing PEP at the initial visit, and giving women both easily remembered information about side-effects and anti-emetic medications to alleviate the common side-effect of nausea. However, the research suggested that anti-emetics alone do not result in better compliance, but should be combined with at home follow-up services to meet clients' needs for emotional support in the period after the rape, to reinforce information about PEP after the immediate trauma (when recall is better), and to promote drug taking.
References
* The CDC makes no recommendations for the use of PEP for persons seeking care within 72 hours after non-occupational exposure to blood, genital secretions, or other potentially infectious body fluids of a person of unknown HIV status, when such exposure would represent a substantial risk for transmission if the source were HIV-infected. In this situation, clinicians are advised to evaluate PEP's risks and benefits on a case-by-case basis. PEP is not recommended for people at no substantial risk for HIV transmission or those who seek care more than 72 hours after exposure. ** Notably, other alternative regimens are possible, and new antiretroviral medications might become available that lead to changes in these recommendations. This article was reproduced with permission of the Mera journal, the leading publication of continuing medical education for health professionals in the English-speaking countries of Africa. (info@fsg.co.uk, www.fsg.co.uk). |
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