Model Sees Pluses and Minuses With Test-and-Treat in Los Angeles MSM

An HIV test-and-treat policy for men who have sex with men (MSM) in Los Angeles County would prevent new HIV infections and save lives, according to results of a mathematical modeling study. But the rate of multidrug-resistant virus would almost double.

The HPTN 052 trial demonstrated that immediate versus delayed antiretroviral therapy for people diagnosed with HIV prevents HIV transmission to steady sex partners. That finding led health policy strategists to formulate a test-and-treat strategy promoting wider HIV testing and immediate antiretroviral therapy for everyone who tests positive. Some studies in the United States and Canada suggest such a policy would limit new HIV infections, but many questions about test-and-treat remain.

To address these issues, researchers developed an epidemiologic model to simulate the HIV epidemic among MSM in Los Angeles County. The model matched HIV surveillance data across a 10-year period starting in 2000. The investigators then modified the model to simulate a test-and-treat approach. They compared outcomes under the test-and-treat scenario with a status quo scenario for the years 2012 through 2023.

The model determined that adopting test-and-treat would cut new HIV infections by 34% in the target period. Test-and-treat would also reduce mortality by 19% and reduce new AIDS cases by 39% from 2012 through 2023.

But rolling out a test-and-treat program would nearly double the rate of multidrug-resistant HIV, from 4.79% to 9.06%. And test-and-treat would not end the HIV epidemic in Los Angeles County MSM by 2023.

The researchers suggest that “behavioral changes may mitigate the benefits of test-and-treat, and future research should explore implications of these behavioral changes.” The investigators also note that their model did not consider cost, which should be integrated into future research.

Source: Neeraj Sood, Zachary Wagner, Amber Jaycocks, Emmanuel Drabo, Raffaele Vardavas. Test-and-treat in Los Angeles: a mathematical model of the effects of test-and-treat for the population of men who have sex with men in Los Angeles County. Clinical Infectious Diseases. 2013; 56: 1789-1796.

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Written by Mark Mascolini on behalf of the International AIDS Society