Serosorting and Sexual Risk for HIV Infection at the Ego-Alter Dyadic Level: An Egocentric Sexual Network Study Among MSM in Nigeria.

The objective of this egocentric network study was to investigate engagement in serosorting by HIV status and risk for HIV between seroconcordant and serodiscordant ego-alter dyads. Respondent-driving sampling was used to recruit 433 Nigerian men who have sex with men (MSM) from 2013 to 2014. Participant (ego) characteristics and that of five sex partners (alters) were collected. Seroconcordancy was assessed at the ego level and for each dyad. Among 433 egos, 18 % were seroconcordant with all partners. Among 880 dyads where participants knew their HIV status, 226 (25.7 %) were seroconcordant, with 11.7 % of HIV positive dyads seroconcordant and 37.0 % of HIV negative dyads seroconcordant. Seroconcordant dyads reported fewer casual sex partners, less partner concurrency, and partners who had ever injected drugs, but condom use did not differ significantly. Serosorting may be a viable risk reduction strategy among Nigerian MSM, but awareness of and communication about HIV status should be increased. Future studies should assess serosorting on a partner-by-partner basis.