Post-exposure prophylaxis affordability: a clearer reality

Low-Beer et al. [1] and Pinkerton et al. [2] recently provided interesting perspectives on the affordability of HIV post-exposure prophylaxis (PEP) both at a local and a national level. Unfortunately, the authors conclusions may be incorrect, especially in the light of recent experience with HIV PEP, and may mistakenly discourage an important means of HIV prevention. In the article by Low-Beer et al. [1], the authors estimated that 1391 of 5100 gay and bisexual men in Vancouver's West End engage in an average of three ‘high-risk incidents’ per year. If all of these men took HIV PEP after each incident for the 4 week prescribed period, the authors calculated that the medication costs would be Can$2 259 780, which would overwhelm the entire province's finances for HIV PEP. This analysis probably greatly overestimates the costs of an HIV PEP program for this population. Several important considerations, such as demand, eligibility, risk and regimen stratification, should reduce the cost of providing HIV PEP. First, the authors’ estimate of individuals requesting HIV PEP per year is probably too high, as evidenced by findings elsewhere. In a 16 month highly publicly advertised HIV PEP program for the San Francisco community, 401 participants sought HIV PEP [3,4]. In a purposefully less advertised program in Boston [5], approximately 60 individuals have received HIV PEP since 1997. For comparison, recent metropolitan area population estimates are 6.8 million for San Francisco and 5.6 million for Boston, 558 000 for the city of Vancouver, and 4 million for British Columbia [6,7]. Second, not all those who seek HIV PEP will be elibible. Some individuals will not present within the recommended 72 h exposure period. Others will have engaged in sexual encounters not meriting HIV PEP consideration, such as unprotected intercourse between two known HIV-uninfected partners. Third, in an effective HIV PEP program, ideally only one high-risk incident per patient should occur, and multiple requests should be discouraged. In the San Francisco program, only 13% of patients requested a second course [5]. Fourth, not all patients will complete the prescribed regimen. Additional information may become available in follow-up that leads to the discontinuation of the medication. Alternatively, patients may terminate treatment themselves. Despite aggressive follow-up and counselling, only 80% of patients in San Francisco and 73% in Boston took treatment for the full 28 days [3–5]. Fifth, not all sexual exposures require three-drug therapy. A stratified approach using a three-drug regimen for higher and a two-drug regimen for lower risk behaviors should be employed. In their letter, Pinkerton et al.[2] estimated that using the Centers for Disease Control and Prevention's 1997 US$600 million funds for HIV prevention would provide 550 000 HIV PEP two-drug regimens, but would prevent only 880 HIV infections. There are a number of problems with this analysis. First, their estimate of a two-drug regimen (US$1092) is high, and so is either the cost of a three-drug regimen, or it includes other costs. Second, it is misleading to mix different kinds of healthcare prevention costs and to imply government funding of HIV PEP. The primary prevention endeavors of the Centers for Disease Control and Prevention have no relationship to HIV PEP costs, and would necessarily exist independently of any HIV PEP campaign. Furthermore, the United States government will not bear the costs of HIV PEP. Individuals who seek HIV PEP in the United States will probably have to pay for it by themselves or through their insurers, as they would any other treatment. Third, although the ratio of HIV infections prevented to those treated appears to be low, in other forms of prophylaxis, such as for rabies, it is surely far lower. In a well-designed HIV PEP program, proper patient selection would improve this ratio. In any case, it is inappropriate to discourage an intervention simply because it may help only a small group of people. A short time ago some shamefully considered HIV prevention not to be cost-worthy because only marginalized members of society were presumed to be at risk. Non-occupational HIV PEP is, of course, of unknown efficacy. The presumptions of its value, however, are based upon good evidence from occupational HIV PEP work, animal data, perinatal studies, and preliminary non-occupational HIV PEP experience. Primary prevention campaigns undoubtedly reduce the spread of HIV. This invaluable means of prevention does not assist those who have recently been exposed to HIV despite these campaigns. In order to help all affected individuals, we should concentrate on providing both types of HIV prevention in appropriate manners, with a more realistic view of costs, and with adequately funded separate budgets. Roland Clayton Merchant