Aims: While suboptimal adherence to statin medication has been quantified in real-world patient settings, a better understanding of its impact is needed, particularly with respect to distinct problems of medication taking. Our aim was to synthesize current evidence on the impacts of statin adherence, discontinuation and persistence on cardiovascular disease and mortality outcomes.
Methods: We conducted a systematic review of peer-reviewed studies using a mapped search of Medline, Embase and International Pharmaceutical Abstracts databases. Observational studies that met the following criteria were included: defined patient population;statin adherence exposure; defined study outcome [i.e. cardiovascular disease (CVD), mortality]; and reporting of statin-specific results.
Results: Overall, 28 studies were included, with 19 studies evaluating outcomes associated with statin adherence, six with statin discontinuation and three with statin persistence. Among adherence studies, the proportion of days covered was the most widely used measure, with the majority of studies reporting increased risk of CVD (statistically significant risk estimates ranging from 1.22 to 5.26)and mortality (statistically significant risk estimates ranging from 1.25 to 2.54) among non-adherent individuals. There was greater methodological variability in discontinuation and persistence studies. However, findings of increased CVD (statistically significant risk estimates ranging from 1.22 to 1.67) and mortality (statistically significant risk estimates ranging from 1.79 to 5.00) among nonpersistent individuals were also consistently reported.
Conclusions: Observational studies consistently report an increased risk of adverse outcomes associated with poor statin adherence. These findings have important implications for patients and physicians and emphasize the importance of monitoring and encouraging adherence to statin therapy.