Background: Accurate measurement of adherence to product use is an ongoing challenge in microbicide trials.
Methods: We compared adherence estimates using 2 applicator tests (a dye stain assay [DSA] and an ultraviolet light assay [UVA]), the Wisebag (an applicator container that electronically tracks container openings), and self-reported adherence (ability, frequency, and percent missed doses). Healthy, HIV-negative, nonpregnant US women aged 23 to 45 years received a Wisebag and 32 applicators filled with placebo gel were instructed to insert 1 applicator daily for 30 days, returned the Wisebag and all applicators, and completed an exit interview. Emptied applicators were tested by UVA and then DSA, and scored by 2 blinded readers. Positive and negative controls were randomly included in applicator batches.
Results: Among 42 women enrolled, 39 completed the study. Both DSA and UVA yielded similar sensitivity (97% and 95%) and specificity (79% and 79%). Two participants had fully inoperable Wisebags, and 9 had partially inoperable Wisebags. The proportion of participants considered to have high adherence (≥80%) varied: 43% (Wisebag), 46% (UVA), 49% (DSA), and 62% to 82% (self-reports). For estimating high adherence, Wisebag had a sensitivity of 76% (95% confidence interval, 50%–93%) and a specificity of 85% (95% confidence interval, 62%–97%) compared with DSA. Although 28% of participants reported forgetting to open the Wisebag daily, 59% said that it helped them remember gel use.
Conclusions: Dye stain assay and UVA performed similarly. Compared with these tests, self-reports overestimated and Wisebag underestimated adherence. Although Wisebag may encourage gel use, the applicator tests currently seem more useful for measuring use in clinical trials.
A study assessing methods of vaginal gel application adherence found that the Wisebag, an electronic adherence monitor, encouraged gel use, but the 2 applicator tests were more accurate for measuring use in clinical trials.
From the *Women’s Global Health Imperative, RTI International, San Francisco, CA; †Center for AIDS Prevention Studies (CAPS) Department of Medicine, UCSF, San Francisco, CA; ‡The Population Council, New York, NY; §Albert Einstein College of Medicine and Montefiore Medical Center, Bronx, NY; and ¶Albert Einstein Cancer Center, Bronx, NY
Acknowledgments: The authors thank the women who participated in this study for their time and effort and Daniel Zaccaro for statistical advice. They would also like to acknowledge the contributions of Jennifer Walsh, Nicole Marshall, Lisa Felder, Randall Teeter, Ashley Huber, and Letisha Vaughan from the Albert Einstein College of Medicine and Montefiore Medical Center; José Fernández-Romero, Stan Mierzwa, Deb Tolenaar, Chung Wu, and Tom Zydowsky from the Population Council; and Andrea Hanson from RTI International and other study team members for their critical contributions to the development and implementation of this study.
Conflict of interest: The authors declare that there are no conflicts of interest.
Parts of this manuscript were presented at The International Association of Providers of AIDS Care (June 2–4, 2013; Miami, FL).
Sources of support: This study was supported, in part, through RTI International research and development funds, The Harold and Muriel Block Institute for Clinical and Translational Research at Einstein and Montefiore (National Institutes of Health [NIH] 8UL1 TR001073), Einstein-Montefiore Center for AIDS Research (NIH AI-051519), NIH CA-148966, and the Microbicide Trials Network, which is funded by the National Institute of Allergy and Infectious Diseases (5UM1AI068633), the Eunice Kennedy Shriver National Institute of Child Health and Human Development, and the National Institute of Mental Health. The findings and conclusions presented in this article are solely the responsibility of the authors and do not necessarily represent the official views of RTI, Einstein-Montefiore Medical Center, the Population Council, or the NIH.
Correspondence: Ariane van der Straten, PhD, MPH, RTI International, 351 California St, Suite 500, San Francisco, CA 94104. E-mail: firstname.lastname@example.org.
Received for publication June 25, 2013, and accepted September 29, 2013.