Assessment of adherence to oral antipsychotic medications: What has changed over the past decade?

Abstract Introduction In a previous review, spanning 3 decades, we found that self-report and other non-objective measures were the primary means of assessing adherence to oral antipsychotic medications for individuals with schizophrenia. Moreover, consensus regarding the definition of adherence was completely lacking. Here, we examined the next decade of studies to determine what may have changed. Method We searched the peer reviewed literature published between January 1, 2007 and December 31, 2017 using Google scholar, Science Direct, CINAHL, PsychINFO, PsychARTICLES and Medline. Search terms were medication adherence or medication compliance or medication acceptance or medication follow-through or medication concordance or medication persistence AND schizophrenia. We included articles that assessed adherence behavior. Results The search yielded 663 articles, 363 of these were eliminated. Included studies represent over 560,000 individuals. Definitions of adherence remain variable with cutoffs from 67% to 95%. Subjective measures of adherence remain the most commonly used. However, the use of objective measures has significantly increased, as has the use of electronic claims data. However, the absolute number of studies using objective measures remains low and very few approaches identify the amount of medication actually taken. Conclusions Some movement toward more standardization and the use of more objective measures of adherence has been made over the past decade. However, objective measures continue to be underutilized and definitions remain variable. Assessing adherence in less than optimal ways calls into question the results of studies purporting to identify reasons for problem adherence and to elucidate the relationships among adherence and other variables.