ORIGINAL PAPER Notes on the Frequency of Routinely Collected and Self-Reported Behavioral Data in HIV Prevention Trials Douglas J. Taylor • Che-Chin Lie • Mark A. Weaver • Elizabeth Tolley • Lut Van Damme • Vera Halpern • Paul Feldblum • Folasade Ogunsola • Orikomaba Obunge • Gita Ramjee • Michel Alary • Florence Mirembe Published online: 19 October 2010 Ó Springer Science+Business Media, LLC 2010 Abstract HIV prevention trials typically randomize thousands of participants to active or control intervention arms, with regular (e.g. monthly) clinic visits over one or more years of follow-up. Because HIV infection rates are often lower than 3 per 100 person-years even in high prevalence settings, tens of thousands of clinic visits may take place before the number of infections required to achieve adequate study power has been observed. In addition to clinical outcomes, the multitude of study visits provides an opportunity to assess adherence and related participant behaviors in great detail. These data may be used to refine counseling messages, gain insight into patterns of behavior, and perform supporting analyses in an attempt to obtain more precise estimates of treatment efficacy. Exploratory analyses were performed to assess how our understanding of participant behaviors and their relationships to biological outcomes in two recent pre- vention trials might have been impacted had the frequency of routine behavioral data collection been reduced from monthly to just months 1, 3, 6, 9, and 12. Results were comparably informative in the reduced case, suggesting that unnecessarily extensive amounts of routine behavioral data may be collected in these trials. Keywords Adherence Á Microbicide Á Trajectory analysis Background In the absence of an effective vaccine, considerable interest has focused on the development of new technologies to reduce the risk of HIV infection in settings where programs to promote abstinence, being faithful, and consistent use of condoms have proven inadequate. Recently investigated products have included diaphragms [1], anti-retroviral based prophylaxis [2], and topical microbicides [3–5]. Because HIV infection is typically a rare outcome, well- powered effectiveness trials of HIV prevention methods may require thousands of participants and many thousands of person-years of follow-up [6]. Subjects make frequent (often monthly) clinic visits for HIV testing and risk- reduction counseling, management of adverse events (AEs), and the withdrawal of product when required by protocol (e.g. if a participant becomes pregnant and regu- latory approval has not been obtained to use the product during pregnancy [7]). Since adherence to most interven- tions is in the hands of participants, frequent adherence counseling is also essential. The resulting tens of thousands of clinic visits provide an opportunity to assess self- reported product adherence and related behaviors in great detail. D. J. Taylor (&) Á C.-C. Lie Á M. A. Weaver Á E. Tolley Á L. Van Damme Á V. Halpern Á P. Feldblum FHI, 2224 East Highway 54, Durham, NC 27713, USA e-mail: dtaylor@fhi.org F. Ogunsola College of Medicine, University of Lagos, Lagos, Nigeria O. Obunge University of Port Harcourt Teaching Hospital, Port Harcourt, Nigeria G. Ramjee HIV Prevention Research Unit, South African Medical Research Council, Durban, South Africa M. Alary URESP, Centre de recherche FRSQ du CHA universitaire de Que ´bec, Quebec, QC, Canada F. Mirembe Makarere University, Kampala, Uganda 123 AIDS Behav (2011) 15:389–395 DOI 10.1007/s10461-010-9822-9