That scenario would see a gain of 2.2 million QALYs, with an incremental cost-effectiveness ratio, compared with no PrEP, of $216,480 per QALY.

On the other hand, if only 20% of men who have sex with men took PrEP, the number of infections prevented and cost would be lower, at 62,759 over 20 years and $95 billion, respectively.

There would be a gain of 550,166 QALYs, with an incremental cost-effectiveness ratio, compared with no PrEP, of $172,091 per QALY.

But targeting just the men who have sex with men considered to be at high risk – those with five or more sex partners a year - would do considerably better, the researchers found.

In that group, thought to be about 20% of all men who have sex with men, starting PrEP would prevent 167,143 new infections over 20 years, at a total cost of $75 billion over current care. And that scenario would gain 1.4 million QALYs, with an incremental cost-effectiveness ratio of $52,443 per QALY, compared with no PrEP.

But even if only one in five of the high-risk population took the daily pill, it would prevent 41,061 new infections over two decades, cost a net of $14 billion, and gain 352,840 QALYs, with a cost-effectiveness ratio of $40,279 compared with no PrEP, they found.

All the models assume that the current cost of the daily pill – about $26 – but analysis found that cost-effectiveness would be better if the cost dropped below $15 or if the risk reduction was greater than 75%.

Primary source: Annals of Internal Medicine
Source reference: Juusola JL, et al “The cost-effectiveness of preexposure prophylaxis for HIV prevention in the United States in men who have sex with men” Ann Intern Med 2012; 156.