A systematic review of measures of medication adherence in consumers with unipolar depression.

OBJECTIVE: To identify and evaluate the range of adherence measures used to assess different phases of medication adherence (initiation, implementation, and discontinuation) to antidepressants, including the psychometric properties of the measures.

METHODS: This systematic review followed the PRISMA statement. Medline, Embase, International Pharmaceutical Abstracts, CINAHL and PsychINFO were searched (1994-2015) for articles which reviewed or reported the psychometric properties of adherence measures in adults with unipolar depression without co-morbidity. Included articles were reviewed for the reliability and validity of their adherence measures.

RESULTS: 26 studies met the inclusion criteria. Most assessed medication adherence at implementation and/or discontinuation phases. Self-report measures were the most frequently used, followed by electronic lid devices and pharmacy records. Standardized self-report measures such as Morisky, Green, and Levine Self-Reported Medication Taking Scale (MGLS) and Antidepressant Adherence Scale (AAS) demonstrated acceptable reliability and validity, while medication claims data showed good reliability as a long-term measure.

CONCLUSIONS: Although the psychometric properties of various measures have been evaluated across the three phases of adherence, a standout measure with strong reliability and validity was not apparent. No single measure demonstrated reliability and validity throughout the adherence process. A range of different subjective and objective adherence measures is recommended to assess medication adherence across the different phases.