Effectiveness of interventions by community pharmacists to improve patient adherence to chronic medication: A systematic review

OBJECTIVE: To systematically review the impact of interventions by community pharmacists on patients' adherence with chronic medication. DATA SOURCES: A MEDLINE search (1966-November 30, 2003) and a review of reference sections were done to identify all pertinent English- and German-language journal articles. Search terms included compliance, adherence, persistence, discontinuation, pharmacist, and intervention. STUDY SELECTION AND DATA EXTRACTION: From each relevant study, the following data were extracted: study design, country, disease, number of patients, patients' age and gender, type of intervention, duration of follow-up, method of measurement of adherence and adherence rate, and data concerning the quality of the included studies. DATA SYNTHESIS: A total of 162 studies were identified, of which 18 matched our inclusion criteria. Twelve were randomized controlled trials and 6 were non-crossover single-group trials. Eight studies showed significant improvement of adherence at one or more time points. Eight studies did not show any effect, 7 of which were randomized controlled trials. In most studies, adherence rates at baseline were high compared with rates reported in the general population. Counseling, monitoring, and education during weekly or monthly appointments showed some effect. However, these same types of interventions showed no effect in other studies. The overall quality of the included studies was low. CONCLUSIONS: Currently, it is impossible to identify an overall successful adherence-improving strategy performed by pharmacists. More well-designed and well-conducted studies on the effectiveness of interventions by a community pharmacist to improve patient adherence to chronic medication need to be performed.