Factors associated with antidepressant medication adherence and adherence-enhancement programmes: a systematic literature review.

Medication adherence is critical to the efficacy of available treatment for depression in primary care settings. This review identifies factors associated with adherence and what is known about the effectiveness of adherence-enhancement programmes. A comprehensive systematic review of English language publications from January 2002 to October 2011 was conducted using the following databases: PUBMED/MEDLINE, PsycINFO and the Cochrane database. Twenty-one studies met the inclusion criteria for adherence-enhancement evaluations. Eleven of the studies evaluated demonstrated significantly positive effects on adherence; the remaining 10 reported mixed or no effects. Similar to previous literature reviews, factors shown to be associated with adherence were multifactorial and in this analysis were grouped as patient, condition and comorbidities, therapy or treatment, patient–provider relationship and healthcare system level. Adherence improved most notably in studies that included sustainable system and patient-targeted changes. Evaluating adherence-enhancement interventions is key to promoting successful approaches; however, a number of gaps exist between intervention and implementation: (1) the cost in resources and time to implement and sustain these programmes is unknown, (2) specific details about which subgroups of patients are best helped with such programmes is not clear, and (3) what specific processes or content are critical to programme success is still to be identified. There are sufficient data supporting the substantial need for planning and implementing adherence interventions despite reported mixed results. Primary care providers are often positioned to impact patients' adherence; however, practice constraints can limit their implementation.