Objective: Medication nonadherence is a serious issue in clinical trials, especially in studies of substance abuse disorders. Measuring and confirming adherence is critical to ensuring that collected data is accurate and interpretable. This study evaluated the feasibility and success of a smartphone-based approach (Cellphone Assisted Remote Observation of Medication Adherence [CAROMA]) to visually confirm medication adherence in a clinical trial.

Method: Medication adherence was confirmed visually via smartphones provided to participants in a double-blind, randomized, placebo-controlled trial for cannabis dependence. Every morning, subjects (n=20) were video-called by staff who observed consumption of study medication. Adherence was also assessed with weekly face-to-face visits, pill counts and plasma drug levels. Subjects were paid for completing daily CAROMA visits, and for returning the smartphone at study completion.

Results: CAROMA confirmed 96.04% adherence to medication. Concordance between expected and actual remaining study medication counted at weekly study visits was 87.69%. Subjects assigned to active study medication had detectable plasma drug levels, while those assigned to placebo did not. CAROMA was estimated to cost approximately $100 per subject per week - a total of $300.24 per subject for the 3-week outpatient portion of the trial.

Conclusion: This pilot study demonstrates the feasibility, success and cost-effectiveness of CAROMA to facilitate and confirm medication adherence in a clinical trial. Preliminary findings support larger and longer studies, and possibly applying this approach to clinical care - especially in other populations with high rates of medication nonadherence.