title: Temporal trends in HIV-1 incidence and risk behaviours in men who have sex with men in Bangkok, Thailand, 2006-13: an observational study.
abstract: BACKGROUND
  HIV-1 incidence in men who have sex with men (MSM) is often difficult to estimate. We therefore assessed temporal trends in HIV-1 incidence and behavioural risk factors in MSM in Bangkok, Thailand, from 2006 to 2013.
  
  
  METHODS
  In this observational study, we used data for clients attending the Silom Community Clinic for voluntary counselling and testing (VCT) services and from the Bangkok MSM Cohort Study (BMCS) to investigate trends in HIV incidence per 100 person-years per quarter in both cohorts. During VCT, basic demographic data were gathered at registration. However, no behavioural risk data were gathered. In the BMCS, we gathered demographic and behavioural data at baseline and at regular study visits using audio computer-assisted self-interviewing. Questions were included about potential risk factors such as drug use, sexual practices, and how often condoms were used. We also analysed behavioural risk factors in the BMCS cohort, using a restricted cubic spline function for time.
  
  
  RESULTS
  From 2006 to 2013, 8176 MSM came for VCT; 1999 (24%) clients were initially seronegative and returned for another test. 235 (12%) individuals seroconverted. The overall HIV-1 incidence was 5.5 per 100 person-years (95% CI 4.8-6.3), with an increasing trend (adjusted p=0.02). In the BMCS, 1372 people were seronegative at baseline; 1259 (92%) had more than one follow-up test and 238 (17%) seroconverted. The overall HIV-1 incidence was 5.3 per 100 person-years (95% CI 4.7-6.1), with an increase and then a decline (inverted U-shaped curve, p=0.0001). Individuals aged 21 years and younger were at significantly higher risk of HIV infection than were those aged 30 years and older in the in the VCT (rate ratio 2.29, 95% CI 1.88-2.78, p<0.0001) and BMCS cohorts (1.99, 1.50-2.65, p<0.0001). Overall, drug use (p=0.03), drug use to enhance sex (p=0.0006), use of drugs for erectile dysfunction (p<0.0001), and 100% condom use (p<0.0001) increased over time, whereas the proportion of individuals reporting receptive anal intercourse decreased (p=0.004).
  
  
  CONCLUSIONS
  With a sustained high HIV-1 incidence and increasing drug use in MSM in Bangkok, we urgently need innovative and acceptable HIV prevention interventions, especially for young MSM.
  
  
  BACKGROUND
  US Centers for Disease Control and Prevention.
authors.affiliation: Thailand Ministry of Public Health - US Centers for Disease Control and Prevention Collaboration, Nonthaburi, Thailand; Division of HIV/AIDS Prevention, Centers for Disease Control and Prevention, Atlanta, GA, USA; Division of Preventive Medicine and Public Health, University of California, San Francisco, CA, USA.
authors.forename: Frits
authors.initials: F
authors.lastname: van Griensven
authors.affiliation: Thailand Ministry of Public Health - US Centers for Disease Control and Prevention Collaboration, Nonthaburi, Thailand; Division of HIV/AIDS Prevention, Centers for Disease Control and Prevention, Atlanta, GA, USA. Electronic address: tholtz@cdc.gov.
authors.forename: Timothy H
authors.initials: TH
authors.lastname: Holtz
authors.affiliation: Thailand Ministry of Public Health - US Centers for Disease Control and Prevention Collaboration, Nonthaburi, Thailand.
authors.forename: Warunee
authors.initials: W
authors.lastname: Thienkrua
authors.affiliation: Thailand Ministry of Public Health - US Centers for Disease Control and Prevention Collaboration, Nonthaburi, Thailand.
authors.forename: Wannee
authors.initials: W
authors.lastname: Chonwattana
authors.affiliation: Thailand Ministry of Public Health - US Centers for Disease Control and Prevention Collaboration, Nonthaburi, Thailand.
authors.forename: Wipas
authors.initials: W
authors.lastname: Wimonsate
authors.affiliation: Thailand Ministry of Public Health - US Centers for Disease Control and Prevention Collaboration, Nonthaburi, Thailand.
authors.forename: Supaporn
authors.initials: S
authors.lastname: Chaikummao
authors.affiliation: Thailand Ministry of Public Health - US Centers for Disease Control and Prevention Collaboration, Nonthaburi, Thailand.
authors.forename: Anchalee
authors.initials: A
authors.lastname: Varangrat
authors.affiliation: Thailand Ministry of Public Health - US Centers for Disease Control and Prevention Collaboration, Nonthaburi, Thailand.
authors.forename: Tareerat
authors.initials: T
authors.lastname: Chemnasiri
authors.affiliation: Thailand Ministry of Public Health - US Centers for Disease Control and Prevention Collaboration, Nonthaburi, Thailand.
authors.forename: Wichuda
authors.initials: W
authors.lastname: Sukwicha
authors.affiliation: Thailand Ministry of Public Health - US Centers for Disease Control and Prevention Collaboration, Nonthaburi, Thailand; Division of HIV/AIDS Prevention, Centers for Disease Control and Prevention, Atlanta, GA, USA.
authors.forename: Marcel E
authors.initials: ME
authors.lastname: Curlin
authors.affiliation: Division of HIV/AIDS Prevention, Centers for Disease Control and Prevention, Atlanta, GA, USA.
authors.forename: Taraz
authors.initials: T
authors.lastname: Samandari
authors.affiliation: Department of Disease Control, Thai Ministry of Public Health, Nonthaburi, Thailand.
authors.forename: Anupong
authors.initials: A
authors.lastname: Chitwarakorn
authors.affiliation: Thailand Ministry of Public Health - US Centers for Disease Control and Prevention Collaboration, Nonthaburi, Thailand.
authors.forename: Philip A
authors.initials: PA
authors.lastname: Mock
mesh_terms: D000328:Adult; D015331:Cohort Studies; D015658:HIV Infections / Q000453:epidemiology* / Q000523:psychology*; D018451:Homosexuality, Male / Q000523:psychology*; D006801:Humans; D015994:Incidence; D008297:Male; D012309:Risk-Taking; D012725:Sexual Behavior / Q000523:psychology; D012747:Sexual Partners / Q000523:psychology; D013785:Thailand / Q000453:epidemiology; D055815:Young Adult