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

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.

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.

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.

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.