Drug and Medical Cost Effects of a Drug Formulary Change With Therapeutic Interchange for Statin Drugs in a Multistate Managed Medicaid Organization

Abstract

Of the 3,636 patients who met the study inclusion criteria and were converted from atorvastatin to an alternate statin drug, 129 patients (3.5%) switched back to atorvastatin following the TI. The average statin cost per claim in the 12-month post-TI period was Dollars 70.93, 9.5% less than the average cost in the 12-month pre-TI period (Dollars 78.40). The average cost per patient per year (PPPY) for statin laboratory tests (lipid panels, creatine kinase tests, and liver function tests) increased by 31.5% to Dollars 16.15 in the post-TI period compared with Dollars 12.28 PPPY in the pre-TI period, and medical office visit costs increased by 44.9% to Dollars 20.70 PPPY in the post-TI period compared with Dollars 14.29 PPPY in the preperiod. These increased costs related to the medical management of statin therapy were overwhelmed by an 11.7% reduction in statin drug costs, from Dollars 793.69 PPPY in the pre-TI period to Dollars 701.01 PPPY in the post-TI period, resulting in a net 10.0% reduction for combined statin costs and related medical costs, from Dollars 820.27 PPPY in the pre-TI period to Dollars 737.87 in the post-TI period. After limiting the analysis to patients who did not convert from atorvastatin to pravastatin (which cost more than atorvastatin before the rebate) and controlling for the influence of potential confounders, statin expenditure decreased by 33% (P < 0.001). Multivariate models indicated no statistically significant differences in the costs related to the medical management of statin therapy after the TI compared with before the TI.