Non-opioid recreational drug use and a prolonged HIV outbreak among men who have sex with men in Taiwan: An incident case-control study, 2006–2015

Background/purpose: Limited data are available on the role of illicit non-injecting drug use in a prolonged HIV outbreak that predominantly affected men who have sex with men (MSM) in Taiwan since 2006. We aimed to assess associations between specific types of drug use and incident HIV infections in this outbreak. Methods: We conducted a retrospective case–control study among MSM clients at voluntary counselling and testing (VCT) service at National Taiwan University Hospital (Taipei, Taiwan). We used BED IgG-capture enzyme immunoassay to identify incident HIV infection (cases), individually matched to HIV-negative MSM clients (controls) by HIV testing date. We used a structured questionnaire to obtain the information on illicit drug use and sexual risk behaviors. Results: From a total of 15,305 MSM client visits during 2006–2015, 387 cases were matched to 1012 controls. Use of inhaled nitrites (adjusted odds ratio [aOR] 2.1), MDMA (aOR 2.9), amphetamines (aOR 1.6), and ketamine (aOR 1.5) were independently associated with incident HIV infection. Polydrug (≥2 drugs) use was associated with the highest risk (aOR 4.3; 95% CI 2.6–7.2). While the proportion of MSM VCT clients who reported use of any recreational drug remained stable during 2006–2015 (average: 9.7%, P: 0.38), there was a shift in specific types of drug use, from MDMA/ketamine to inhaled nitrites/amphetamine, after 2011 (all Ps