Willingness-to-accept reductions in HIV risks: conditional economic incentives in Mexico.

The objective of this study was to measure willingness-to-accept (WTA) reductions in risks for HIV and other sexually transmitted infections (STI) using conditional economic incentives (CEI) among men who have sex with men (MSM), including male sex workers (MSW) in Mexico City. A survey experiment was conducted with 1,745 MSM and MSW (18-25 years of age) who received incentive offers to decide first whether to accept monthly prevention talks and STI testing; and then a second set of offers to accept to stay free of STIs (verified by quarterly biological testing). The survey used random-starting-point and iterative offers. WTA was estimated with a maximum likelihood double-bounded dichotomous choice model. The average acceptance probabilities were: 73.9 % for the monthly model, and 80.4 % for the quarterly model. The incentive-elasticity of participation in the monthly model was 0.222, and 0.515 in the quarterly model. For a combination program with monthly prevention talks, and staying free of curable STI, the implied WTA was USD$ 288 per person per year, but it was lower for MSW: USD$ 156 per person per year. Thus, some of the populations at highest risk of HIV infection (MSM and MSW) seem well disposed to participate in a CEI program for HIV and STI prevention in Mexico. The average WTA estimate is within the range of feasible allocations for prevention in the local context. Given the potential impact, Mexico, a leader in conditional cash transfers for human development and poverty reduction, could extend that successful model to targeted HIV/STI prevention.