Should AIDS treatment be viewed as a complement to HIV prevention or as an alternative? AIDS activists have strongly argued that HIV prevention is impossible without AIDS treatment, that the two interventions are strong complements. Their principal evidence for this claim is the demonstrable fact that the presence of AIDS treatment increases the demand for HIV testing. In Tuesday’s presentation here at the CGD, preeminent HIV testing researcher Susan Allen argued that the enormous expansion of HIV testing, because it has predominantly been provided to individuals, not couples, has had little beneficial impact on reducing risk behavior – and in combination with ‘be faithful’ messaging may actually have accelerated the spread of the epidemic among couples who are not aware that they have different HIV test results.As an economist, I have a wholly theoretical prejudice in favor of couples testing and counseling. One of the most influential papers ever written in economics was entitled: “The market for lemons” . That’s “lemons” as in “used cars”, not fruit. For those whose tastes run towards “freakonomics”, the Wikipedia article on this paper and on the ensuing research program it generated is fascinating reading. That paper and the ensuing Nobel-prize winning flow of research argued that markets function very poorly or not at all when the parties to a transaction have different amounts of information about the commodity being exchanged – the problem of “asymmetric information”. The fact that the seller of a used car knows all of the bad treatment he has given the car, but the buyer has no way of knowing, means that, on average, used cars are harder to sell than they should be - and then sell for less, on average, than they are worth. Of course, people are ingenious and have invented a variety of tricks to compensate for this problem. One trick is to only buy a used car from someone whose car maintenance behavior you have been able to observe first hand, such as your next door neighbor or brother-in-law. In these cases, information is symmetrically distributed between the two parties and the transaction is efficient.The extension to sexual transactions is direct. Suppose two people are negotiating a sexual transaction. In the absence of couple testing, either person might know his or her own HIV status but neither can reliably know the status of the other. The fact that information is asymmetric discourages the formation and the survival of monogamous partnerships. A partial solution to this problem would be a certificate of HIV status given to an individual that he or she could then choose to show to a spouse or potential future partner. But such certificates would be the object of counterfeiting rings. The only real solution to this asymmetric information problem is to offer couple counseling, a process in which each member of the partnership learns their own and their partner’s status – in the presence of a trained and experienced counselor to help them cope with the implications for their relationship of any of the possible joint testing outcomes.So in today’s presentation, after proposing that the international community aim to achieve an “AIDS transition,” partly in order to improve the incentives for HIV prevention, and that a “cash-on-delivery” approach to rewarding HIV prevention will lead local leaders to use pay-for-performance to reward a variety of potentially effective prevention efforts, perhaps including couple testing, I urged the audience to consider couple testing on these theoretical grounds.Then Susan Allen rose to say that when counselors are trained explicitly in couple counseling, and individuals seeking testing are encouraged to bring their primary sexual partners for joint testing, HIV testing does indeed work to reduce risk behavior among both “discordant” (couples with one positive and one negative partner) and “concordant-negative” (both are negative) couples.Although there are unfortunately no randomized trials to support her proposition, the fact that such couples in Uganda had an infection rate of 12 % when they were NOT jointly tested (See Quinn et. al., ungated here) whereas those across the border in Rwanda had an infection rate of less than 3 % when they WERE jointly tested is suggestive of a large benefit to couple testing. (The latter statistic comes from Susan’s unpublished data from >5000 couple-years of follow-up between 2003-2009). Similarly in two studies of discordant couples in Zambia, the couples without joint testing had a rate of infection of 20 % (See Hira et. al., ungated here.) compared to a rate of 7 % among the couples with joint testing (See Fideli et. al., ungated here). And then the statistic that I find most compelling is that the rate of infection among couples who are jointly tested and are both HIV negative was less than 1 % in one study (See Roth et. al, subscription required).One of the most frequently expressed fears about couple testing is that, when the woman is positive, she will be stigmatized and abused. But in Zambia, fewer than 4 % of discordant couples separated in the year after joint testing and counseling [See Kempf et. al., ungated here], a percentage which might be as low as the rate of separation in the absence of couple testing.Of course, when comparing data from these various observational studies, there is no guarantee that the jointly tested couples are comparable to the couples not jointly tested. Among many reasons for possible lack of comparability, the most prominent is that couples who accept joint testing and counseling may be exactly the ones who are most predisposed to safe behavior. But until a more rigorous evaluation shows me otherwise, both the established theory of asymmetric information and Susan’s observational evidence support a donor policy that favors couple testing over individual testing – and strongly support the performance of more rigorous research on couple testing.
CGD blog posts reflect the views of the authors, drawing on prior research and experience in their areas of expertise. CGD is a nonpartisan, independent organization and does not take institutional positions.