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PLoS One. 2013 Dec 18;8(12):e81997. doi: 10.1371/journal.pone.0081997. eCollection 2013.

No evidence of sexual risk compensation in the iPrEx trial of daily oral HIV preexposure prophylaxis.

Author information

1
Gladstone Institute of Virology and Immunology, San Francisco, California, United States of America ; University of California, Berkeley, California, United States of America.
2
University of California San Francisco, San Francisco, California, United States of America.
3
Fenway Institute, Fenway Health, Boston, Massachusetts, United States of America ; Beth Israel Deaconess Medical Center, Boston, Massachusetts, United States of America.
4
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.
5
Center for Health, Intervention and Prevention, University of Connecticut, Storrs, Connecticut, United States of America.
6
Gladstone Institute of Virology and Immunology, San Francisco, California, United States of America.
7
Division of Clinical Immunology and Allergy, School of Medicine, University of São Paulo, São Paulo, Brazil.
8
Fundación Ecuatoriana Equidad, Guayaquil, Guayas, Ecuador.
9
Laboratorio de AIDS e Imunologia Molecular, Hospital Geral de Nova Iguacu, Rio de Janeiro, Brazil.
10
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.

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.

DESIGN AND 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.

PMID:
24367497
PMCID:
PMC3867330
DOI:
10.1371/journal.pone.0081997
[Indexed for MEDLINE]
Free PMC Article

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