title: Uptake of pre-exposure prophylaxis, sexual practices, and HIV incidence in men and transgender women who have sex with men: a cohort study.
abstract: BACKGROUND
  The effect of HIV pre-exposure prophylaxis (PrEP) depends on uptake, adherence, and sexual practices. We aimed to assess these factors in a cohort of HIV-negative people at risk of infection.
  
  
  METHODS
  In our cohort study, men and transgender women who have sex with men previously enrolled in PrEP trials (ATN 082, iPrEx, and US Safety Study) were enrolled in a 72 week open-label extension. We measured drug concentrations in plasma and dried blood spots in seroconverters and a random sample of seronegative participants. We assessed PrEP uptake, adherence, sexual practices, and HIV incidence. Statistical methods included Poisson models, comparison of proportions, and generalised estimating equations.
  
  
  RESULTS
  We enrolled 1603 HIV-negative people, of whom 1225 (76%) received PrEP. Uptake was higher among those reporting condomless receptive anal intercourse (416/519 [81%] vs 809/1084 [75%], p=0·003) and having serological evidence of herpes (612/791 [77%] vs 613/812 [75%] p=0·03). Of those receiving PrEP, HIV incidence was 1·8 infections per 100 person-years, compared with 2·6 infections per 100 person-years in those who concurrently did not choose PrEP (HR 0·51, 95% CI 0·26-1·01, adjusted for sexual behaviours), and 3·9 infections per 100 person-years in the placebo group of the previous randomised phase (HR 0·49, 95% CI 0·31-0·77). Among those receiving PrEP, HIV incidence was 4·7 infections per 100 person-years if drug was not detected in dried blood spots, 2·3 infections per 100 person-years if drug concentrations suggested use of fewer than two tablets per week, 0·6 per 100 person-years for use of two to three tablets per week, and 0·0 per 100 person-years for use of four or more tablets per week (p<0·0001). PrEP drug concentrations were higher among people of older age, with more schooling, who reported non-condom receptive anal intercourse, who had more sexual partners, and who had a history of syphilis or herpes.
  
  
  CONCLUSIONS
  PrEP uptake was high when made available free of charge by experienced providers. The effect of PrEP is increased by greater uptake and adherence during periods of higher risk. Drug concentrations in dried blood spots are strongly correlated with protective benefit.
  
  
  BACKGROUND
  US National Institutes of Health.
authors: Gladstone Institutes, San Francisco, CA, USA; University of California, San Francisco, CA, USA; San Francisco AIDS Foundation, San Francisco, CA, USA. Electronic address: rgrant@gladstone.ucsf.edu.
authors: Robert M
authors: RM
authors: Grant
authors: University of Colorado, Anschutz Medical Campus, Aurora, CO, USA.
authors: Peter L
authors: PL
authors: Anderson
authors: Gladstone Institutes, San Francisco, CA, USA.
authors: Vanessa
authors: V
authors: McMahan
authors: University of California, San Francisco, CA, USA; San Francisco Department of Public Health, San Francisco, CA, USA.
authors: Albert
authors: A
authors: Liu
authors: University of Connecticut, Storr, CT, USA.
authors: K Rivet
authors: KR
authors: Amico
authors: Gladstone Institutes, San Francisco, CA, USA.
authors: Megha
authors: M
authors: Mehrotra
authors: Stroger Hospital of Cook County, Chicago, IL, USA.
authors: Sybil
authors: S
authors: Hosek
authors: INMENSA, Lima, Peru.
authors: Carlos
authors: C
authors: Mosquera
authors: ACSA, Iquitos, Peru.
authors: Martin
authors: M
authors: Casapia
authors: Equidad, Guayaquil, Ecuador.
authors: Orlando
authors: O
authors: Montoya
authors: University of California, San Francisco, CA, USA; San Francisco Department of Public Health, San Francisco, CA, USA.
authors: Susan
authors: S
authors: Buchbinder
authors: FIOCRUZ, Rio de Janeiro, Brazil.
authors: Valdilea G
authors: VG
authors: Veloso
authors: Fenway Health, Boston, MA, USA.
authors: Kenneth
authors: K
authors: Mayer
authors: University of Chiang Mai, Chiang Mai, Thailand.
authors: Suwat
authors: S
authors: Chariyalertsak
authors: Desmond Tutu Health Foundation, Cape Town, South Africa.
authors: Linda-Gail
authors: LG
authors: Bekker
authors: University of Sao Paulo, Sao Paulo, Brazil.
authors: Esper G
authors: EG
authors: Kallas
authors: Projeto Praça Onze, Hospital Escola Sâo Francisco de Assis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
authors: Mauro
authors: M
authors: Schechter
authors: INMENSA, Lima, Peru.
authors: Juan
authors: J
authors: Guanira
authors: University of Colorado, Anschutz Medical Campus, Aurora, CO, USA.
authors: Lane
authors: L
authors: Bushman
authors: National Institutes of Health, Bethesda, MD, USA.
authors: David N
authors: DN
authors: Burns
authors: Gilead Sciences, Foster City, CA, USA.
authors: James F
authors: JF
authors: Rooney
authors: University of California, San Francisco, CA, USA.
authors: David V
authors: DV
authors: Glidden
mesh_terms: D000293:Adolescent; D000328:Adult; D019380:Anti-HIV Agents / Q000097:blood / Q000627:therapeutic use*; D015331:Cohort Studies; D005260:Female; D015658:HIV Infections / Q000453:epidemiology / Q000517:prevention & control*; D006801:Humans; D015994:Incidence; D008297:Male; D012725:Sexual Behavior; D063106:Transgender Persons
chemical_list: D019380:Anti-HIV Agents