Government Backs Universal HIV Testing

5/06/2013 11:12:00 AM
Via Laura Newman, the United States Preventive Services Task Force, an independent government-funded agency that reviews research and makes recommendations about preventive medical services utilization (for example, recommendations on who should get tested for HIV), has now issued a recommendation that HIV testing should be included as part of the regular blood screening for all adults over 15 years old. Since this is what I argued for in a previous post here, it makes me think that maybe someone actually reads my blog.

As regular readers will recall, I did a crude cost-benefit analysis in a previous post and showed that on net, annual testing of all adults would be welfare-improving. As a side note, a number of readers misinterpreted this welfare analysis. I did not argue that the testing should be paid for by the government, though that's not something I'd necessarily oppose, nor did I argue that testing would be net savings to the US treasury. It will certainly cost a lot more money than it saves, but the statistical value of the lives it would save is much more than the cost. And from a social welfare perspective, that's true no matter who is paying for the tests and treatments. As a side note to my side note, I want to confess two major flaws in my back-of-the-envelope calculation: 1) I understated the amount that the treatments would cost, because I implicitly assumed that people who don't get treated die immediately from the infection. I should have used an overlapping generations model, and the treatment costs would be several times larger than the $400 million figure I came up with. This error, however, is mostly offset by the fact that 2) I did not count the savings from the fact that universal testing would reduce transmission rates by as much as 90%. That is, I implicitly assumed that detection and treatment had no effect on transmission. The blog post wasn't meant to be a scientific cost-benefit analysis, just a starting point for thinking about the costs. But it would have been wise to mention those two shortcomings in particular.

I will also add that while I based my calculation on the census count of adults, which the Census defines as 18+, the task force recommends regular testing for everyone 15 years old and up, so the total cost of testing is somewhat larger than the \$12 billion I calculated (worth noting that the CDC recommends routine testing starting at age 13). Starting testing at ages 13 or 15 is a better choice rather than 18 because, for sexual health purposes, puberty is the appropriate demarcation between adults and children. Any population that is likely to be engaged in penetrative sexual activity is at risk for HIV. It is important to start treatment immediately after the infection (it has even been shown that early enough treatment, within a month, can functionally cure HIV infected people). And it is absurd to suggest that 15 to 18 year olds are all virgins.

I mention this because the American Academy of Family Physicians has disagreed with the recommendations, saying that 15 to 18 year olds should not be included in the recommendation. That's not to say that they thing no 15 to 18 year olds should be tested, but that testing should only be done if they are part of an elevated-risk demographic, such as sexually active gay boys.

CDC estimates that 1.3 out of 10,000 people between 15 and 19 years old have HIV. An interesting question is how likely these early-infection cases are to die from failing to start treatment early enough. It seems likely to me that the propensity would be quite high: research shows that patients, especially minors, aren't likely to disclose their risk factors for HIV (like gay sex or intravenous drug use) to their doctors, and that on average, symptoms don't start until 10 years after infection, when it is too late to completely prevent AIDS. Moreover, this 10-year window when the kid isn't aware of his infection is the period of his life when he is most likely to transmit it to other people. So while the infection rates are relatively low for this demographic, it seems to me that the potential benefits of testing are still pretty high. And for a mostly meaningless welfare calculation, the statistical value of 1.3 lives is about \$4 million, the cost of treatment is \$26,000, and the cost of testing 10,000 people is \$480,700. That's net benefits of  \$3,493,300 per 10,000 adolescents. Of course that's mostly meaningless because 1)We need to subtract the costs and benefits of people who would have been tested and treated anyway, 2) the value of a statistical life I used was based on a population-weighted average age of somewhere around 40, not the 15 to 19 year olds under consideration 3) the benefits from reduced transmission rates were not included 3) we can't really say that 1.3 per 10,000 lives would be saved by the testing/treatment.

But still, that is a starting point for thinking about the cost-benefit. Medical doctors are aren't as comfortable with the idea of putting a dollar value on a statistical life, and I think that is too their discredit. To be sure, I think the empirical estimates of the value of a life are wildly inaccurate. I've seen estimates range from \$0.8 million to \$80 million, and there is convincing evidence that they systematically overstate the value because of publication bias (statistically insignificant results don't get published), which is why I used lower-end estimates. But on the other hand, whenever groups like the American Academy of Family Physicians make recommendations on things like HIV testing, they are implicitly placing a value on a statistical life--and to an extremely rough approximation, they have just said that they think value of a 15 to 19 year old's expected life span is less than \$506,700--well below even the lowest published estimates. At least I make my values calculation explicit.