A simple, novel method for assessing medication adherence: capsule photographs taken with cellular telephones

Medication nonadherence is an important factor in clinical practice and research methodology. Although many methods of measuring adherence have been investigated, there is as yet no "gold standard." We compared the usefulness and accuracy of a novel measure of adherence, photographs taken by cellular telephones with 2 incumbents: capsule count and the Medication Event Monitoring System (MEMS).

Twenty subjects participated in a clinical trial of the efficacy of modafinil for the treatment of methamphetamine dependence. Subjects were issued cell phones and medication in MEMS Cap equipped bottles and were instructed to take 1 capsule a day for 8 weeks, recording adherence with both systems. Pill counts were recorded at weekly inpatient visits. Subjects were paid for participation and for each capsule photograph and the returned medication bottle with MEMS Cap.

Capsule count-indicated adherence (proportion of prescribed medication taken) was 94.9%. When compared with capsule count, the novel method was found to underestimate adherence, whereas MEMS overestimated adherence. By using the dosing time data collected, we determined that subjects who dosed at a consistent time daily were more likely to adhere to the prescribed regimen. We also detected discrepancies in the timestamps recorded by MEMS.

Capsule photographs are a useful measure of adherence, allowing more accurate time measures and more frequent adherence assessment than MEMS or capsule count. Given the ubiquity of cellular telephone use, and the relative ease of this adherence measurement method, we believe it is a useful and cost-effective approach.