Adherence to escitalopram treatment in depression: a study of electronically compiled dosing histories in the 'Depression: the search for phenotypes' study

Poor adherence to depression treatment is common. Understanding determinants of poor adherence to therapy is crucial to ensure optimal clinical outcomes. The aim of this study was to describe characteristics of dosing history in participants with depression receiving once daily escitalopram. Participants were randomly assigned to interpersonal psychotherapy (IPT) or pharmacotherapy. Participants assigned to IPT who did not evidence a response or remission had escitalopram added to their treatment. Adherence to pharmacotherapy was assessed using an electronically monitored pill cap (MEMS). Fifty-four participants on escitalopram alone and 32 on escitalopram+IPT were monitored. After 200 days, 71.7% of the participants in the escitalopram group and 54.8% of those in the escitalopram+IPT group were still engaged with the dosing regimen. Of those engaged in the dosing regimen, 17.9% (average over 210 days) of the participants did not take their medication (nonexecution). In 69% of the days participants took the correct dosage required. On average, participants had three drug holidays and the mean length of a holiday was 7 days per patient. No difference in adherence patterns was observed between patients receiving escitalopram alone vs. IPT+escitalopram. Early discontinuation of treatment and suboptimal daily execution of the prescribed regimen are the most common facets of poor adherence in this study population.