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Appropriateness of Hydroxyethylcellulose Gel as a Placebo Control in Vaginal Microbicide Trials: A Comparison of the Two Control Arms of HPTN 035

Richardson, Barbra A. PhD*,†; Kelly, Cliff MS; Ramjee, Gita PhD; Fleming, Thomas PhD*; Makanani, Bonus MBBS, FCOG§; Roberts, Sarah MPH; Musara, Petina BSW; Mkandawire, Nkhafwire MSc#; Moench, Thomas PhD**; Coletti, Anne MS††; Soto-Torres, Lydia MD‡‡; Karim, Salim A. MBChB, PhD§§for the HPTN 035 Study Team

JAIDS Journal of Acquired Immune Deficiency Syndromes: May 1st, 2013 - Volume 63 - Issue 1 - p 120–125
doi: 10.1097/QAI.0b013e31828607c5
Epidemiology and Prevention

Objective: To compare the 2 control arms of HPTN 035 [a hydroxyethylcellulose (HEC) gel control arm and a no-gel control arm] to assess the behavioral effects associated with gel use and direct causal effects of the HEC gel on sexually transmitted infections (STIs), pregnancy, and genital safety.

Design: Randomized trial with 1 blinded (HEC gel) and 1 open-label (no-gel) control arms.

Methods: HIV-uninfected, sexually active women were randomized into the HEC gel arm (n = 771) and into the no-gel arm (n = 772) in 5 countries. Participants in the HEC gel arm were instructed to insert the study gel intravaginally <1 hour before each vaginal sex act. Data on sexual behavior, adherence, safety, pregnancy, and STIs were collected quarterly for 12–30 months of follow-up.

Results: During follow-up, mean reported condom use in the past week was significantly higher in the no-gel arm (81% versus 70%, P < 0.001). There were no significant differences, after adjusting for this differential condom use, between the 2 arms in the rates of genital safety events, pregnancy outcomes, or STIs, including HIV-1.

Conclusions: In this large randomized trial, we found no significant differences between the no-gel and HEC gel arms in the rates of genital safety events, pregnancy outcomes, or STIs. These results aid interpretation of the results of previous vaginal microbicide trials that used the HEC gel as a control. The HEC gel is suitable as a control for ongoing and future vaginal microbicide studies.

*Department of Biostatistics, University of Washington, Seattle, WA;

Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, WA;

HIV Prevention Research Unit, Medical Research Council, South Africa;

§Department of Obstetrics and Gynecology, College of Medicine—Johns Hopkins University Research Project, Blantyre, Malawi;

University of Alabama at Birmingham, Birmingham, AL/Centre for Infectious Disease Research in Zambia, Zambia;

UZ-UCSF Research Programme, Harare, Zimbabwe;

#UNC Project, Lilongwe, Malawi;

**ReProtect, Inc, Baltimore, MD;

††Family Health International, Research Triangle Park, NC;

‡‡National Institutes of Allergy and Infectious Diseases, Bethesda, MD; and

§§CAPRISA, University of KwaZulu-Natal, South Africa.

Correspondence to: Barbra A. Richardson, PhD, University of Washington, MS359909, 325 Ninth Avenue, Seattle, WA 98104-2499 (e-mail:

HPTN 035 was funded by the US National Institutes of Health. The study was designed and implemented by the HIV Prevention Trials Network (HPTN) and the Microbicides Trials Network (MTN). The HPTN (U01AI46749) has been funded by the National Institute of Allergy and Infectious Diseases (NIAID), the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), National Institute of Drug Abuse, and National Institute of Mental Health (NIMH). The MTN (U01AI068633) has been funded by NIAID, NICHD, and NIMH. The study products were provided free of charge by Indevus Pharmaceuticals, Inc and ReProtect, Inc. The US Agency for International Development provided funding for manufacturing of BufferGel for this study.

Presented at the Microbicides 2010 Conference in Pittsburgh, PA, in May 2010.

Received August 02, 2012

Accepted November 21, 2012

© 2013 Lippincott Williams & Wilkins, Inc.