Objectives: 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).
Method: 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.
Results: 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.
Conclusions: 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.
From the Addiction & Pharmacology Research Laboratory, California Pacific Medical Center Research Institute, San Francisco, CA.
Send correspondence and reprint requests to Gantt P. Galloway, PharmD, California Pacific Medical Center Research Institute, 3555 Cesar Chavez, 7th Floor, San Francisco, CA 94110. e-mail: GallowG@cpmcri.org.
Supported by Award Number NIH DAO18179 from the National Institute on Drug Abuse.
The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institute On Drug Abuse or the National Institutes of Health.
GPG designed the study and wrote and edited this article; JRC analyzed the data and assisted in writing and editing; JEG assisted in data analysis, writing, and editing; KF assisted in data analysis and wrote and edited the article; and JEM assisted in designing the study and in editing the article.
Received January 12, 2010
Accepted July 22, 2010