Measurement of psychiatric treatment adherence

Objective: Nonadherence to medications for mental disorders substantially limits treatment effectiveness and results in higher rates of relapse, hospitalization, and disability. Accurate measurement of medication adherence is important not only in adherence research but also in clinical trials in which medications are being evaluated and in clinical practice where failure to detect nonadherence results in premature medication changes, unnecessary polypharmacy, and greater likelihoods of functional deteriorations and hospitalizations. This is a review of psychiatric treatment adherence methods and measures arising from a meeting on "Methodological Challenges in Psychiatric Treatment Adherence Research" held on September 27-28, 2007, in Bethesda, MD, and organized by the National Institute of Mental Health (NIMH). Methods: This paper reviews the range of modalities currently available for assessing adherence behavior including pill counts, pharmacy records, technology-assisted monitoring, biological assays, and a range of self-report and interviewer-rated scales. Measures of adherence attitudes are also reviewed. Results: Each of the adherence measures described are imperfect estimates of actual medication ingestion, but each provides informative estimates of adherence or the attitudinal factors associated with adherence. Measure selection depends on a range of factors including the patient sample, the context in which the measure is being used, and the clinical outcomes expected from various levels of nonadherence. The use of multiple measures of adherence is encouraged to balance the limitations of individual measures. Conclusion: While adherence assessment has become increasingly sophisticated in recent years, there remains a need for refinement and expansion on currently available methods and measures.