Impact of an adherence intervention on the effectiveness of tenofovir gel in the CAPRISA 004 trial
Doris Duke Medical Research Institute, Nelson R Mandela School of Medicine, University of KwaZulu-Natal, Private Bag X7, Congella 4013, South Africa
High adherence is important in microbicide trials, but no adherence interventions to date have demonstrated empiric improvements in microbicide adherence or effectiveness. Approximately midway during the CAPRISA 004 trial, we implemented a novel adherence intervention (Adherence Support Program - ASP), based on an Information-Motivation-Behavioral Skills model and incorporating a Motivational Interviewing approach. We assessed the impact of the ASP on adherence and tenofovir gel effectiveness using a before-and-after comparison. Of the 889 women in the trial, 774 contributed 486.1 women-years of follow-up pre-ASP and 828 contributed 845.7 women-years of follow-up post-ASP. Median adherence rose from 53.6 % pre-ASP to 66.5 % post-ASP. Detectable tenofovir levels increased from 40.6 % pre-ASP to 62.5 % post-ASP in 64 women who had paired tenofovir drug samples. Gel effectiveness improved post-ASP; HIV incidence in the tenofovir gel arm was 24 % lower pre-ASP compared to 47 % lower post-ASP. Following implementation of the ASP, microbicide adherence improved with a concomitant increase in the effectiveness of tenofovir gel. © 2014 Springer Science+Business Media New York.
adenine; anti human immunodeficiency virus agent; gel; phosphonic acid derivative; tenofovir; topical antiinfective agent; adult; analogs and derivatives; controlled study; double blind procedure; epidemiology; female; gel; health behavior; HIV Infections; human; incidence; intervention study; medication compliance; motivational interviewing; psychological model; psychology; randomized controlled trial; socioeconomics; South Africa; statistics and numerical data; treatment outcome; Adenine; Adult; Anti-HIV Agents; Anti-Infective Agents, Local; Double-Blind Method; Female; Gels; Health Behavior; HIV Infections; Humans; Incidence; Intervention Studies; Medication Adherence; Models, Psychological; Motivational Interviewing; Organophosphonates; Socioeconomic Factors; South Africa; Treatment Outcome
USAID, United States Agency for International Development