Buprenorphine utilization following removal of prior authorization requirements in the Kentucky Medicaid population

To evaluate changes in buprenorphine dispensing for treatment of opioid use disorder (OUD) among Kentucky Medicaid enrollees following the removal of prior authorization (PA) requirements for the transmucosal buprenorphine combination product.

We analyzed Kentucky Medicaid claims from 1/1/2016 through 6/30/2023 to identify enrollees with OUD during each quarter (Q1/2017-Q2/2023), using a 12-month lookback window. Segmented regression analysis was used for statistical modeling of an interrupted time series (ITS) design to assess changes in the quarterly proportion of enrollees with OUD receiving buprenorphine for OUD treatment, focusing on the effect of PA removal. The effective date of the PA removal was February 22, 2019 and thus Q1/2019 was treated as a roll-in period for policy implementation.

The quarterly proportion of enrollees with OUD receiving buprenorphine ranged from 0.29 to 0.44 across the study period. Prior to removal of PA requirements for transmucosal buprenorphine, this proportion was increasing at a modest rate (ITS pre-policy slope +0.009; 95% CI 0.008-0.011). The immediate estimated effect of the full PA removal implementation (Q4/2018 to Q2/2019) was a 4-percentage-point increase (level change +0.04; 95% CI 0.03-0.05) followed by a deceleration in growth (slope change -0.006; 95% CI -0.008- -0.005).

Removal of transmucosal buprenorphine PA requirements for Kentucky Medicaid enrollees was associated with a significant immediate increase in buprenorphine dispensing for OUD treatment. Future research should evaluate how post-PA removal trends interact with the Kentucky Medicaid's coverage of methadone for OUD beginning in Q3/2019.