title: No evidence of sexual risk compensation in the iPrEx trial of daily oral HIV preexposure prophylaxis.
abstract: OBJECTIVE
  Preexposure prophylaxis (PrEP) with emtricitabine/tenofovir disoproxil fumarate (FTC/TDF) reduced HIV acquisition in the iPrEx trial among men who have sex with men and transgender women. Self-reported sexual risk behavior decreased overall, but may be affected by reporting bias. We evaluated potential risk compensation using biomarkers of sexual risk behavior.
  
  
  METHODS
  Sexual practices were assessed at baseline and quarterly thereafter; perceived treatment assignment and PrEP efficacy beliefs were assessed at 12 weeks. Among participants with ≥1 follow-up behavioral assessment, sexual behavior, syphilis, and HIV infection were compared by perceived treatment assignment, actual treatment assignment, and perceived PrEP efficacy.
  
  
  RESULTS
  Overall, acute HIV infection and syphilis decreased during follow-up. Compared with participants believing they were receiving placebo, participants believing they were receiving FTC/TDF reported more receptive anal intercourse partners prior to initiating drug (12.8 vs. 7.7, P = 0.04). Belief in receiving FTC/TDF was not associated with an increase in receptive anal intercourse with no condom (ncRAI) from baseline through follow-up (risk ratio [RR] 0.9, 95% confidence interval [CI]: 0.6-1.4; P = 0.75), nor with a decrease after stopping study drug (RR 0.8, 95% CI: 0.5-1.3; P = 0.46). In the placebo arm, there were trends toward lower HIV incidence among participants believing they were receiving FTC/TDF (incidence rate ratio [IRR] 0.8, 95% CI: 0.4-1.8; P = 0.26) and also believing it was highly effective (IRR 0.5, 95% CI: 0.1-1.7; P = 0.12).
  
  
  CONCLUSIONS
  There was no evidence of sexual risk compensation in iPrEx. Participants believing they were receiving FTC/TDF had more partners prior to initiating drug, suggesting that risk behavior was not a consequence of PrEP use.
authors.affiliation: Gladstone Institute of Virology and Immunology, San Francisco, California, United States of America ; University of California, Berkeley, California, United States of America.
authors.forename: Julia L
authors.initials: JL
authors.lastname: Marcus
authors.affiliation: University of California San Francisco, San Francisco, California, United States of America.
authors.forename: David V
authors.initials: DV
authors.lastname: Glidden
authors.affiliation: Fenway Institute, Fenway Health, Boston, Massachusetts, United States of America ; Beth Israel Deaconess Medical Center, Boston, Massachusetts, United States of America.
authors.forename: Kenneth H
authors.initials: KH
authors.lastname: Mayer
authors.affiliation: University of California San Francisco, San Francisco, California, United States of America ; Bridge HIV, San Francisco Department of Public Health, San Francisco, California, United States of America.
authors.forename: Albert Y
authors.initials: AY
authors.lastname: Liu
authors.affiliation: University of California San Francisco, San Francisco, California, United States of America ; Bridge HIV, San Francisco Department of Public Health, San Francisco, California, United States of America.
authors.forename: Susan P
authors.initials: SP
authors.lastname: Buchbinder
authors.affiliation: Center for Health, Intervention and Prevention, University of Connecticut, Storrs, Connecticut, United States of America.
authors.forename: K Rivet
authors.initials: KR
authors.lastname: Amico
authors.affiliation: Gladstone Institute of Virology and Immunology, San Francisco, California, United States of America.
authors.forename: Vanessa
authors.initials: V
authors.lastname: McMahan
authors.affiliation: Division of Clinical Immunology and Allergy, School of Medicine, University of São Paulo, São Paulo, Brazil.
authors.forename: Esper Georges
authors.initials: EG
authors.lastname: Kallas
authors.affiliation: Fundación Ecuatoriana Equidad, Guayaquil, Guayas, Ecuador.
authors.forename: Orlando
authors.initials: O
authors.lastname: Montoya-Herrera
authors.affiliation: Laboratorio de AIDS e Imunologia Molecular, Hospital Geral de Nova Iguacu, Rio de Janeiro, Brazil.
authors.forename: Jose
authors.initials: J
authors.lastname: Pilotto
authors.affiliation: Gladstone Institute of Virology and Immunology, San Francisco, California, United States of America ; University of California San Francisco, San Francisco, California, United States of America.
authors.forename: Robert M
authors.initials: RM
authors.lastname: Grant
mesh_terms: D000225:Adenine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000627:therapeutic use; D000293:Adolescent; D000328:Adult; D000368:Aged; D019380:Anti-HIV Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D003841:Deoxycytidine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000627:therapeutic use; D000068679:Emtricitabine; D005260:Female; D015658:HIV Infections / Q000517:prevention & control*; D018451:Homosexuality, Male / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D008875:Middle Aged; D063065:Organophosphonates / Q000008:administration & dosage / Q000627:therapeutic use*; D011247:Pregnancy; D012725:Sexual Behavior / Q000706:statistics & numerical data; D000068698:Tenofovir; D063106:Transgender Persons / Q000706:statistics & numerical data; D055815:Young Adult
chemical_list: D019380:Anti-HIV Agents; D063065:Organophosphonates; D003841:Deoxycytidine; D000068698:Tenofovir; D000068679:Emtricitabine; D000225:Adenine