Cardiovascular events in statin recipients: a 3-year record-linkage study on prescription and hospital discharge databases

Background: In the general population, lack of adherence to statins remains a widespread phenomenon and an important matter of concern both in terms of cost-effectiveness and risk-benefit profile. Objectives: To evaluate the occurrence of cardiovascular (CV) events in patients treated with statins in Italy, focusing on the role of adherence to therapy. Methods: We selected Emilia Romagna inhabitants who received statins in Jan-Feb 2005. Drug prescriptions and hospital admissions were analysed for the following 36 months, focusing on CV events, adherence to therapy and patient risk profile. Cox regression was used to assess how the hazard associated with patient risk and to adherence changed over time. Results: Among 137,217 selected patients, 29% experienced CV events over the 3-year period. These events were more frequent in older than 80 yrs (HR 2.70; 95% CI 2.51– 2.89), treated also for hypertension, angina or heart failure (2.44; 2.35-2.53) or using statins for secondary prevention (2.22; 2.17–2.26). Only 24% of statin recipients adhered to therapy over the 3-year period. No matter what risk factors, adherence significantly reduced the occurrence of CVevents (average:—30%). Non-adherent patients showed an increased risk as follows: strongly non-adherent (adjOR 1.19; 95% CI 1.15–1.23), slightly non-adherent (1.25;1.21– 1.30), highly variable over years in the amount of statins received (1.69;1.62–1.77). Conclusions: The present study shows the key role of adherence to statin therapy at any level of patients’ CV risk. The lower odd of CV events in strongly non-adherent patients suggests that this group may include subjects who did not require pharmacological treatment. Whenever statins are appropriately started, cooperation between physician and patient to ensure uninterrupted treatment is the mainstay of appropriateness.