A Comparison of HIV Incidence and Risk Factors Among Subgroups of Men Who Have Sex with Men in Tianjin, China: A Prospective Cohort Study

Abstract

Background: In the past ten years, men who have sex with men (MSM) has become one of the most important high-risk population of HIV in China. However, there is sparse research on the role of subgroups of MSM in driving the HIV epidemic. This study aims to compare HIV incidence among different subgroups of MSM and explore potential risk factors associated with HIV infection. This is the first prospective cohort study that estimates HIV incidence and behavioral risk factors among transgender and substance-using MSM in China.

Methods: In this prospective cohort study, we recruited MSM aged 18 years and above with a history of oral or anal sex in the past six months. Baseline and follow-up visits were completed in Shenlan Public Health Consulting Service Center in Tianjin. The observation period for the cohort was 18 months, with check-ins occurring at six-month intervals. During each visit, participants were asked to fill out a structured questionnaire and free HIV and syphilis tests were provided. The questionnaire covered information on demographics, risk sexual behaviors, and substance use. Cumulative incidence of HIV and syphilis infection were estimated by Kaplan-Meier methods. The risk factors of HIV acquisition was analyzed by Cox regression models with time-dependent variables. We used a descriptive model to calculate odds ratios between predictive factors to reflect their positions in the causal pathway to HIV acquisition.

Findings: From January 2016 to July 2018, 1079 MSM were recruited and 1005 were tested HIV negative at baseline. Among them, 885 participated in the follow-up at least twice and entered the cohort. The overall retention rate was 88·1% (885/1005). Compared with general MSM, transgender and substance-using MSM had much higher frequencies of oral or anal sex and higher proportions of inconsistent condom use. Among transgender MSM, over a half (56·1%, 142/253) used drugs, and the most commonly used drug was amyl nitrite (141/142, 99·3%). Compared with not using amyl nitrite, 90·8% (128/141) reported to have increased libido and 94·3% (133/141) had heightened sexual pleasure after using it. The incidence of HIV acquisition among transgender, substance-using and general MSM was 2·36 (95%CI: 1·18, 4·72), 1·75 (95%CI: 0·79, 3·89) and 1·68 (95%CI: 0·80, 3·52) per 100 PYs, respectively. Non-local residency (adjusted HR=3·23, 95%CI: 1·37, 7·64), inconsistent condom use (adjusted HR=22·40, 95%CI: 7·43, 67·54) and without regular sexual partner (adjusted HR= 4·56, 95%CI: 1·81, 11·49) were independent risk factors for HIV seroconversion.

Interpretation: There were heightened HIV risks and incidence rates among transgender and substance-using MSM, comparing with general MSM. These two subgroups require intensive HIV epidemic surveillance and strengthened behavior prevention. Among MSM in Tianjin, those without local residency, without regular sexual partners, and inconsistent condom use played important roles in driving the HIV epidemic. Future stronger HIV prevention strategies for MSM should be implemented, in particular targeting those non-local and without stable partners.

Funding Statement: M.A.C AIDS Fund (grant number: A-P-15-20660)

Declaration of Interests: The authors declare no competing interests.

Ethics Approval Statement: The study received approval from the institutional review board (IRB) of the National Center for AIDS/STD Control & Prevention, Chinese CDC (Approval number: X160729420). Subjects were provided written informed consent and were given a unique identification number in order to protect participants’ privacy.

Keywords: HIV; AIDS; incidence; men who have sex with men; transgender; substance use