Abstract P100: The Cardiovascular Consequences of Switching From Atorvastatin to Generic Simvastatin in the Netherlands

Abstract

OBJECTIVES In January 2009, an authorisation form was implemented which required Dutch clinicians to justify the prescription of branded statins. The effect was significant switching of patients from atorvastatin to generic simvastatin. However, current prescription data indicates that much of this switching is occurring at less than equipotent doses. We sought to assess the potential consequences in terms of cardiovascular disease (CVD). METHODS Data from a pharmacy database covering the majority of drug dispenses in the Netherlands informed dose-specific patterns of switching from atorvastatin to generic simvastatin among 39,031 Dutch patients in Q1 2009. Dose-specific, lipid-modifying potencies of the two statins were derived from a recently-published meta-analysis. The relationship between reduction in LDL-C achieved by statin therapy and relative reduction in risk of CVD was derived from a recently-published meta-regression. This showed that for every 25mg/dL (0.65mmol/L) reduction in LDL-C, the relative risk (RR) (95% confidence interval [CI]) for any CVD event, a coronary event, stroke and cardiovascular death were 0.86 (95%CI 0.84-0.88), 0.84 (95%CI 0.82-0.86), 0.90 (95%CI 0.86-0.94) and 0.89 (95%CI 0.87-0.92), respectively. RESULTS In Q1 2009, 33.7%, 47.2% and 19.1% of Dutch patients initially on atorvastatin were switched to less potent, equipotent and more potent doses of simvastatin, respectively. The net (weighted-average) effect would have been a 5.6% increase in LDL-C. The predicted relative increases (95%CI) in risk of various cardiovascular events are dependent on baseline LDL-C, and are summarized in the Table . CONCLUSIONS In the Netherlands, many patients are being switched from atorvastatin to generic simvastatin at inferior doses, which might lead to a significant increase in future cardiovascular events. Baseline LDL-C Any cardiovascular event Coronary event Stroke Cardiovascular death 2.0 mmol/L 2.4% (2.1-2.7) 2.7% (2.4-3.1) 1.7% (1.0-2.4) 1.9% (1.4-2.2) 2.5 mmol/L 3.0% (2.6-3.4) 3.4% (3.0-3.9) 2.1% (1.3-3.0) 2.4% (1.7-2.8) 3.0 mmol/L 3.6% (3.1-4.1) 4.1% (3.6-4.6) 2.6% (1.5-3.6) 2.8% (2.1-3.3) 3.5 mmol/L 4.2% (3.6-4.8) 4.8% (4.2-5.4) 3.0% (1.8-4.2) 3.3% (2.4-3.9) 4.0 mmol/L 4.8% (5.5-4.1) 5.5% (4.8-6.2) 3.4% (2.1-4.8) 3.8% (2.7-4.5)