Lack of Association between Retrospectively Collected Pharmacy Refill Data and Electronic Drug Monitoring of Antiretroviral Adherence

Antiretroviral medication refill adherence has not been compared directly to electronic drug monitoring (EDM) in any identifiable published study. We retrospectively studied adults with undetectable HIV titers on highly active antiretroviral therapy. We used Pearson correlation coefficients and receiver operating characteristic curves to relate the two adherence measures, and we used the Wilcoxon rank-sum test to assess the relation between adherence and viral load. In sixty-five subjects, the majority of whom were African American and male with median age of 44 years, pharmacy refill adherence was difficult to collect retrospectively, was not significantly correlated with EDM adherence, and was not significantly related to viral load. Ninety-day supply pharmacy refill adherence correctly classified 95% EDM adherence maximally at 94 days between refills, and the measure was most sensitive for non-adherence at <90 days. Reassessment of the relation between pharmacy refill data and EDM would be warranted when pharmacy refill data is collected as soon as feasible from sources with complete data capture.