High-statin adherence over 5 years of follow-up is associated with improved cardiovascular outcomes in patients with atherosclerotic cardiovascular disease: results from the IMPRES study

Abstract Aims Despite proven benefits of LDL-C lowering among those with atherosclerotic cardiovascular disease (ASCVD), statin adherence remains low. Very little real-world data exist on the effect of long-term statin adherence on cardiovascular outcomes. Methods and results A total of 7339 patients ≥18 years first diagnosed with ASCVD with a statin prescription within 12 months of diagnosis who had 5 years of continuous Select Health insurance or died during Years 2–5, while a member was studied. The proportion of days covered (PDC) was calculated using pharmacy claims for statin use by year, and patients were stratified into pre-defined categories: fully adherent [PDC ≥ 80% for Years 1–5 or until death, n = 353 (4.8%)], short-term-adherent [PDC ≥ 80% for Years 1–3, n = 330 (4.5%)], early-adherent only [PDC ≥ 80% for Year 1, n = 890 (12.1%)], complex-adherent (PDC ≥ 80% in any of Years 2–5, but not Year 1, n = 1292 [17.6%]), and non-adherent [PDC < 80% for Years 1–5 or until death, n = 3942 (72.1%)]. Patients were followed for major adverse clinical events (MACE = death, myocardial infarction, and stroke). Patients averaged 56.4 ± 9.6 years and 76.5% were male. During Year 1, statin adherence was poor, with PDC < 20% in 4007 (54.6%) patients and PDC ≥80% in 1573 (21.4%) patients, which dropped to 16.9% by Year 5. Increased adherence was associated with significantly fewer MACE (11.6%, 17.9%, 21.9%, 21.1%, and 26.4% for those fully adherent, short-term adherent, early-adherent only, complex-adherent, and non-adherent, respectively, P-trend < 0.0001). After adjustment, fully adherent was associated with a significant decrease in MACE (hazard ratio = 0.51, 0.37–0.71). Conclusion Among ASCVD patients with at least 5 years of continuous pharmacy benefits, long-term adherence to statins was associated with decreased long-term MACE in a linear-fashion.