Between February 2009 and May 2012 the NIDA funded Metromates Study was conducted at The Los Angeles Lesbian, Gay and Bisexual and Transgender Center (LA LGBT Center), a community-based organization providing comprehensive health services.

We enrolled 328 men seeking HIV testing at the LA LGBT Center Sexual Health program longitudinal cohort study who met the following criteria: had results from a recent HIV test; at least 18 years of age; male; and reported sex with a male partner in the past 12 months. Eligible participants provided written informed consent; those who had tested HIV-positive (through the sexual health program) provided a specimen for testing of recency of infection. Those testing positive were all verified as newly diagnosed, with a subset classified as recently infected using one of these criteria: a positive test result to RNA nucleic acid amplification testing (NAAT) on a specimen negative by rapid HIV antibody testing or a result indicative of recent infection from the Vironostika detuned assay. The remaining were classified as newly HIV-diagnosed (but not newly infected) and 105 were HIV-negative. Men were enrolled for a year of behavioral follow-up attempted quarterly but only 55% completed any follow-up after enrollment.