Prevalence and Determinants of Adherence to Statin Therapy: A Systematic Review and Meta-Analysis.

AIM: To estimate the prevalence of good adherence to statin therapy and identify demographic and clinical factors associated with adherence among adults prescribed lipid-lowering therapy (LLT) for atherosclerotic cardiovascular disease (ASCVD) prevention.

METHODS

We conducted a systematic search of PubMed and Scopus through May 2025 to identify randomized controlled trials, cohort, nested case-control, and cross-sectional studies evaluating adherence to statin monotherapy. Data were extracted on study design, participant demographics, comorbidities, adherence assessment method and duration, and statin type. A random-effects meta-analysis was performed. Study quality was assessed using the Newcastle-Ottawa Scale, and risk of bias in randomized trials was evaluated with the Cochrane RoB 2 tool. Subgroup and sensitivity analyses examined adherence variations by follow-up duration (<1, 1, >1 year), alternative adherence thresholds, and study quality. "Primary" non-adherence (failure to initiate prescribed therapy) was not reported in any of the included studies.

RESULTS

Seventy-six studies encompassing 5,898,141 participants (median follow-up 24 months) were included. The pooled prevalence of good adherence (≥80% medication use) was 62.4% (95% CI: 58.3-66.5%), lower in primary (57.5%) than secondary (64.4%) prevention settings. Factors associated with lower adherence included female sex (RR=0.92), Black race (RR=0.66), smoking (RR=0.94), depression (RR=0.89), and heart failure (RR=0.96). Higher adherence was observed among older adults (RR=1.34), individuals with myocardial infarction (RR=1.28) or hypertension (RR=1.12), those with ≥2 comorbidities (RR=1.25), and patients with polypharmacy (RR=1.32). Subgroup and sensitivity analyses yielded consistent results.

CONCLUSIONS

Adherence to statin therapy remains suboptimal and is significantly influenced by demographic and clinical factors. Targeted strategies are needed to improve adherence, particularly in high-risk groups.