Measurement of vaginal microbicide adherence using visual inspection as compared to ultra violet light assessment of returned empty gel applicators.
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Introduction Finding a safe, effective and acceptable HIV prevention method is key to preventing new infections in women. Vaginal microbicide trials aim to do so, but adherence to study product remains a challenge in interpretation of study product effectiveness. Accurate and objective measures of adherence are critical in microbicide trials. Methods We compared two applicator tests, visual inspection of returned empty applicators (VIREA) and ultraviolet (UV) light assessment of empty applicators returned as used within a tenofovir (TFV) gel implementation trial. Sensitivity and specificity in a small pilot sample was assessed at two time points, approximately three months apart. Reliability and concordance of the techniques was also assessed. Results Sensitivity and specificity analysis of 24 sample applicators at time point 1 was 75.0% and 66.7% for VIREA and 83.3% and 91.7% for UV light assessment, respectively; Sensitivity and specificity at time point 2 was 100% and 58.3% for VIREA and 100% and 66.7% for UV light assessment, respectively. Participants (n=115, median age 28 years) enrolled in the implementation trial at the Vulindlela Research Clinic, returned 1316 empty TFV applicators as used in January 2015. Assessment outcomes showed 78.8% agreement between VIREA and UV light techniques. Methods concurred that 22% of the returned empty applicators did not appear to be used. UV light assessment identified about 28% less product used, as compared to that returned as used by women. Conclusion UV light assessment appears to be a more accurate and less subjective measure of adherence as compared to VIREA. Further studies are needed to verify accuracy of UV light inspection against available DNA/protein biomarkers. UV light assessment can be used in combination with other biomarkers to identify potential challenges to adherence and inform targeted adherence interventions with the intention of optimizing adherence during microbicide clinical trials.