Cost-effectiveness of PrEP

via Nature Medicine, by Roxanne Khamsi

Clinical trial data are starting to pour in demonstrating that the HIV prevention strategy known as 'pre-exposure prophylaxis' is an effective way of keeping people at high risk of infection disease free. In July, researchers reported at the International AIDS Society Conference in Rome that taking an antiretroviral drug called Truvada offered a 73% protection rate for heterosexual couples in East Africa in which only one person had HIV. At the same meeting, the US Centers for Disease Control and Prevention also announced trial results demonstrating a 63% reduction in transmission among young adults in Botswana taking the pill.

Buoyed by these and similar findings reported last year among men who have sex with men, health policy experts and economists are now debating how best to roll out the strategy to those who might benefit most. Preliminary analyses, experts say, indicate that PrEP should be a cost-effective tool to address the HIV epidemic until more testing and treatment for the disease becomes available.

Last year, even before PrEP was known to be effective for heterosexuals, a team led by Carel Pretorius of the Futures Institute, a global health think tank based in Glastonbury, Connecticut, published a mathematical model assessing the resources needed to apply it. The analysis concluded that administering PrEP to young South African women could—in an optimistic scenario—prevent up to a quarter of all new cases of HIV in the targeted high-risk age group at a cost of as little as $12,500 per each averted infection. The model asserts that this constitutes a worthwhile investment, as long as the reach of antiretroviral treatment for HIV-positive individuals remains low in the country (PLoS ONE 5, e13646, 2010).

In a similar vein but using a different cost metric, Rochelle Walensky, from Harvard Medical School in Boston has unpublished evidence showing that each year of life saved due to PrEP among a comparable South African cohort should cost just $3,600 when taking into account all downstream survival benefits and costs. That price would be considered by the World Health Organization to be “very cost-effective” since it falls well below the country's average annual per capita gross domestic product.

“There were so many people who expected us to say, 'Prove it's cost saving,'” says Walensky. “I thought that was a tall order, but I thought it would likely be cost effective.”

In certain settings, PrEP can cost around $250 per year for a full dose of daily pills and the associated HIV testing and laboratory monitoring. That may sound cheap, but, given shrinking global health budgets around the world, researchers worry about whether the pills will find their way to those who need them most. “Things can be cost effective and even cost saving, but you've still got to find a big lump of cash,” says Timothy Hallett, who studies resource allocation for HIV at Imperial College London.

Even with adequate funding, however, experts emphasize the moral imperative to assure access to medications for people known to carry the virus before giving limited drug supplies to those not yet infected. “I don't see how we could treat uninfected people without first treating infected people,” says Arleen Leibowitz, a health economist at the University of California–Los Angeles.

But, outside the developing world, Leibowitz thinks that those willing to pay out of pocket for the drugs should have that option. “I would not deny PrEP to anyone who would be able to pay for it,” she says. “If you want to do this with your money, that's perfectly legitimate.”

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