Divergent adherence estimates with pharmacokinetic and behavioural measures in the MTN-003 (VOICE) study.

Introduction : In the Microbicide Trial Network MTN-003 (VOICE) study, a Phase IIB pre-exposure prophylaxis trial of daily oral or vaginal tenofovir (TFV), product adherence was poor based on pharmacokinetic (PK) drug detection in a random subsample. Here, we sought to compare behavioural and PK measures of adherence and examined correlates of adherence misreporting. Methods : We included participants with PK and behavioural data from VOICE random subsample. Behavioural assessments included face-to-face interviews (FTFI), audio computer-assisted self-interviewing (ACASI) and pharmacy-returned product counts (PC). TFV concentrations 0.65 for any single or combined behavioural measures. Significant ( p <0.05) correlates of over-reporting included being very worried about getting HIV and being unmarried for the oral group; whereas for the vaginal group, being somewhat worried about HIV was associated with lower risk of over-reporting. Conclusions : PK measures indicated similarly low adherence for the oral and vaginal groups. No behavioural measure accurately predicted PK non-adherence. Accurate real-time measures to monitor product adherence are urgently needed. Trial registration: ClinicalTrials.gov identifier: NCT00705679 Keywords: microbicide; pre-exposure prophylaxis; adherence measurement; pharmacokinetic drug detection; HIV. To access the supplementary material to this article please see Supplementary Files in the column to the right (under Article Tools). (Published: 4 February 2016) Citation: van der Straten A et al. Journal of the International AIDS Society 2016, 19 :20642 http://www.jiasociety.org/index.php/jias/article/view/20642 | http://dx.doi.org/10.7448/IAS.19.1.20642