OBJECTIVES: Since the FDA approval of the proprotein subtilisin/kexin type 9 inhibitor (PCSK9i) class in 2015, utilization has been low. The purpose of this study was to examine prior authorization (PA) decisions (approved or denied) and subsequent PCSK9i possession based on a filled pharmacy claim for alirocumab among Medicare Advantage Prescription Drug (MAPD) patients.

METHODS: A retrospective, claims-based analysis of MAPD patients aged 18-89 years with evidence of an initial PA (index date) for alirocumab between March 1, 2016 and February 28, 2017 was conducted. PA status was further stratified based on prescription claim evidence within 30 days post-index as filled (paid claim) or unfilled (no claim or reversed claim). Demographic and clinical characteristics were identified during the pre-index period and index date. A logistic regression model on possession of alirocumab was fitted using the least absolute shrinkage and selection operator method for variable selection.

RESULTS: A total of 2,098 MAPD members met the inclusion criteria. The mean (SD) number of days between the PA and a pharmacy claim status was 20.9 (34.7) days. Overall, 90.8% of the PAs for alirocumab were approved; however only 22.7% were subsequently filled. Predictors of a filled pharmacy claim for alirocumab were PA approval, low income subsidy support and/or dual eligibility for Medicaid and Medicare status, a lower Deyo-Charlson Comorbidity Index Score, use of a non-statin lipid lowering therapy within 30 days of index, and higher pre-index medical and pharmacy costs.

CONCLUSIONS: While there were a high percentage of MAPD patients with an approved PA for alirocumab, the percentage of patients with evidence of possession of alirocumab was low. This suggests that PA approval status alone is insufficient to ensure patient utilization of alirocumab. Further research is needed to better understand why fill rates among MAPD members are low.