An evaluation of the clinical and economic outcomes associated with switching hyperlipidemic patients to preferred statin therapy in the United States Department of Defense
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To contain costs associated with lipid-lowering therapy, the U.S. Department of Defense awarded a contract for the statin drugs to the manufacturers of cerivastatin and simvastatin. Hyperlipidemic patients were supposed to be converted to the preferred statin on or after October 1, 1999. The primary goal of this study was to evaluate the clinical and economic outcomes associated with switching statin therapy of patients from a non-preferred statin (atorvastatin, fluvastatin, lovastatin or pravastatin) to a preferred statin (cerivastatin or simvastatin). The study was conducted using data from two groups of patients: those for whom statin prescription records were available (called “Pharmacy Group”); and those for whom pre- and post-conversion lipid profiles were available (called “Clinical Group”). There were a total of 181,787 patients in the Pharmacy Group who were converted from a non- preferred to a preferred statin. 58 percent of these patients were converted to simvastatin and 42 percent to cerivastatin. Observation of guidelines provided for equivalent conversion of patients averaged 29.2 percent. The median decrease in preand post-conversion cost per patient per month was $5.35. This translates into a cost avoidance for switched patients of approximately $11.7 million per year. Medication compliance of patients in the Pharmacy Group, estimated by calculation of the Medication Possession Ratio, remained essentially unchanged from pre-conversion period (0.95) to post-conversion period (0.97). Out of the 1,552 primary and secondary prevention patients in the Clinical Group for whom information of NCEP goal status was available, 56.8 percent were at goal before the switch and 59.1 percent were at goal after the switch. When primary and secondary prevention patients were examined separately, the results showed that percent of primary prevention patients at goal decreased from 75.2 percent to 67.0 percent, and the percent of secondary prevention patients at goal increased from 36.4 percent to 50.3 percent. For all patients combined, LDL cholesterol decreased by 5.1 percent, HDL cholesterol increased by 5.8 percent, triglycerides increased by 2.1 percent, and total cholesterol decreased by 0.8 percent. In conclusion, the statin therapy interchange program resulted in considerable cost savings without clinically important changes in clinical outcomes.