A systematic review of interventions to improve adherence to statin medication: What do we know about what works?

Suboptimal adherence to statin medication is common and leads to serious negative health consequences but may respond to intervention. This review evaluated the effectiveness of interventions intended to improve adherence to statin medication. Data sources included peer-reviewed publications from Cochrane Register of Randomized Controlled Trials (RCTs), PubMed, CINAHL, and EMBase indexed between 01 October 2008 and 18 October 2015 and studies from reference lists and technical experts. RCTs that evaluated an intervention targeting adherence to self-administered statin medication for primary or secondary prevention were eligible. Two investigators independently reviewed trials, extracted data, and evaluated risk of bias. Twenty-nine RCTs reporting on 39,769 patients met inclusion. Identified RCTs exhibited methodological weaknesses: all but one failed to set inclusion parameters for medication adherence; nearly half lacked sufficient power to detect meaningful effects; and the majority had a risk of bias. Interventions were categorized into five classes (simplification of regimen, prescription cost coverage, reminders, education and information, and multi-faceted) and effects were pooled within each class. Prescription cost coverage, Hedges' g=0.15, 95%CI [0.11:0.21], simplification of drug regimen, Hedges' g=0.38, 95%CI [0.22:0.55], the provision of education, Hedges' g=0.19, 95%CI [0.01:0.37], and the use of multi-faceted interventions, Hedges' g=0.16, 95%CI [0.05:0.27], had small positive effects on statin adherence relative to usual care and reminders were promising, Hedges' g=0.0.27, 95%CI [-0.05:0.60]. In conclusion, there are some successful interventions to improve adherence to statin medication but the effects are small and additional methodologically rigorous trials are needed.