PCV63 TRENDS IN CONVERSION TO GENERIC ATORVASTATIN AMONG MEDICARE BENEFICIARY STATIN USERS

Abstract

Substituting brand-name medications with generic equivalents provides lower cost options for patients and can mitigate drug expenditures. Brand-name atorvastatin was the most frequently prescribed brand-name statin until generic was available in the United States on 11/30/2011. The objective of our study was to examine frequency and time to conversion to generic atorvastatin for patients who were on brand-name atorvastatin or other statins. We identified Medicare beneficiaries with any new statin prescriptions between 1/1/2007 and 11/30/2011 using the Chronic Conditions Data Warehouse 5% sample. Continuous enrollment in Medicare Parts A, B, and D for a minimum of 12 months prior to initial statin prescription and through 2012 was required. Users who switched statin type before, or did not refill after 11/30/2011, were excluded. Users were followed through 2015 or until censoring/death. We examined the proportion of statin users who switched to generic atorvastatin and the number of refills before switching. Of 43,307 statin users who met the eligibility criteria, 12,660 (29%) switched to generic atorvastatin after 11/30/2011 versus remaining on their current statin. 89% of brand-name atorvastatin users (n=5,420) switched within 1.8 refills on average, followed by 21% of both simvastatin (n=4,883) and brand-name rosuvastatin (n=863) users within 4.8 and 4.9 refills, respectively, and 15% of pravastatin users (n=1,058) within 4.5 refills. The availability of generic atorvastatin resulted in switching among the vast majority of brand-name atorvastatin users and among other statins but at a slower rate. The rapid rate of switching among Lipitor users was likely due to Medicare policy and pharmacies’ ability to substitute automatically to a generic without consulting a prescriber. Brand-name rosuvastatin’s lack of generic availability and simvastatin’s high-intensity dose restriction may have also contributed to switching. Future research should consider how these trends relate to statin expenditures and other effects such as adherence.