Statin switch threatening lipid goals in over 1 million US patients
MedWire News: Switching patients from atorvastatin to generic simvastatin may compromise lipid control, study findings published in the American Journal of Therapeutics suggest.
To contain costs, healthcare payers have implemented a variety of policies to encourage the switch from branded to generic medications, explain Herbert Aronow (Michigan Heart and Vascular Institute, Ann Arbor, USA) and colleagues.
Aronow and team estimate that around 1 million US patients have switched from atorvastatin to simvastatin since generic simvastatin became available in June 2006. However, “higher milligram doses of simvastatin than atorvastatin are required to achieve a similar degree of low-density lipoprotein cholesterol (LDL-C) lowering, and therapeutically equivalent simvastatin doses are not always selected,” the researchers write.
Aronow and colleagues studied trends in LDL-C concentration over 1 year in 383 patients at high risk for cardiovascular disease. The patients had been switched from atorvastatin to simvastatin. The annual change in LDL-C levels in these patients was compared with that in 3830 patients who were also at high risk for cardiovascular disease but remained on atorvastatin.
Of the patients who switched medications, 31.9% moved to a simvastatin dose that was less than therapeutically equivalent to the dose of atorvastatin they had previously been taking. Consequently, the average LDL-C level at the end of the study was significantly higher in those switched to simvastatin (95.1 mg/dl; 5.28 mmol/l) than in those who remained on atorvastatin (87.2 mg/dl; 4.84 mmol/l) despite the fact that LDL-C levels were approximately the same in all patients before the switch took place.
Similarly, after a year of treatment with simvastatin, 62.3% of patients achieved their LDL-C goal of <100 mg/dl (5.56 mmol/l) compared with 74.0% of atorvastatin-treated patients.
The investigators conclude that their study has several limitations. Firstly, their small sample size makes it impossible to determine whether changes in LDL-C observed affected morbidity and mortality.
Secondly, the study included only patients at high risk for cardiovascular disease and cannot be extrapolated to individuals at low risk.
Finally, the authors concede that their findings are biased by the fact that LDL-C data were not available for almost 80% of the original group of patients selected for the study who were switched from atorvastatin to simvastatin.
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By Philip Ford