Are self-reported and self-monitored adherence good proxies for reaching relevant plasma concentrations?: Experiences from a study of anti-depressants in healthy volunteers.

ABSTRACT

BACKGROUND: The use of electronic-based devices to measure and to improve adherence of subjects in clinical trials is increasing. AiCure has developed a mobile technology that is claimed to provide visual confirmation of drug ingestion. While there is evidence suggesting that including such self-monitoring device in a study increases adherence, the quality of the data produced by the device may be questionable. Can the mobile technology reliably distinguish whether a subject takes the study drug or not? METHODS: Adherence was calculated based on exposure, self-reporting and self-monitoring for subjects randomized to an anti-depressant. Levels of adherence and agreement between the three approaches were investigated based on calculation of proportions, two-way tables and receiver operating curves. RESULTS: A total of 214 subjects had measured concentrations of study drug at all three time points (end of weeks 3, 4 and 5), along with adherence data to define proportion of days adherent based on self-reporting and the self-monitoring instrument developed by AiCure. Self-reported adherence proportions were higher than self-monitored adherence proportions, although both were high (>90%). Neither self-reported and self-monitored adherence agreed with exposure-based adherence. CONCLUSION: Both self-reported and self-monitored adherence overestimated adherence. Neither the self-reported nor the self-monitored adherence measure reflected subjects' actual adherence. This prompts for cautiousness when interpreting either of them, and it underlines the need for thorough validation of electronic devices and software that claims to measure adherence. The AiCure instrument may not be able to reliably determine whether the subjects swallow the study medication.