The Effects of Feedback on Adherence to Treatment: A Systematic Review and Meta-analysis of RCTs

CONTEXT: The aim of this systematic review is to determine whether providing feedback, guided by subjective or objective measures of adherence, improves adherence to treatment. EVIDENCE ACQUISITION: Data sources included MEDLINE, Embase, CINAHL, and PsycINFO, and reference lists of retrieved articles. Only RCTs comparing the effect of feedback on adherence outcome were included. Three independent reviewers extracted data for all potentially eligible studies using an adaptation of the Cochrane Library data extraction sheet. The primary outcome, change in adherence, was obtained by measuring the difference between adherence at baseline visit (prior to feedback) and at the last visit (post-feedback). EVIDENCE SYNTHESIS: Twenty-four studies were included in the systematic review, and 16 found a significant improvement in adherence in the intervention group (change in adherence range, -13% to +22%), whereas adherence worsened in the control group (change in adherence range, -32% to 10.2%). Meta-analysis included six studies, and the pooled effect showed that mean percentage adherence increased by 10.02% (95% CI=3.15%, 16.89%, p=0.004) more between baseline and follow-up in the intervention groups compared with control groups. Meta-regression confirmed that study quality, form of monitoring adherence, delivery of feedback, or study duration did not influence effect size. CONCLUSIONS: Feedback guided by objective or subjective measures of adherence improves adherence and, perhaps more importantly, prevents worsening of adherence over time even when only small absolute improvements in adherence were noted. Increased use of feedback to improve treatment adherence has the potential to reduce avoidable healthcare costs caused by non-adherence.