Association of State-Imposed Restrictions on Gabapentin with Changes in Prescribing in Medicare

Between August 2016 and July 2018, three states classified gabapentin as a Schedule V drug and nine states implemented prescription drug monitoring program (PDMP) regulation for gabapentin. It is highly unusual for states to take drug regulation into their own hands. The impact of these changes on gabapentin prescribing is unclear.

To determine the effect of state-imposed regulation on gabapentin prescribing for Medicare Part D enrollees from 2013 to 2018.

Population-based difference-in-difference(DID) analysis study utilizing the Medicare Part D Prescriber Public Use File.

All eligible Medicare Part D prescribers excluding those outside of the fifty states and the District of Columbia were included in our analysis. Prescriber data and key sociodemographic variables were organized by state and year. States with a gabapentin schedule change or PDMP regulation enacted before 2019 were included in the intervention group. For the Schedule V DID analysis, a control group of the ten highest opioid-prescribing states was used.

States with gabapentin schedule changes or PDMP regulation before January 1, 2019, were included and compared to control states that did not implement these policies.

Total days' supply of gabapentin per enrollee per year was the primary outcome variable.

The mean total days' supply of gabapentin per enrollee increased 41% from 19.71 to 27.81 total days' supply per enrollee per year between 2013 and 2018. After adjustment, Schedule V gabapentin regulation resulted in a reduction of 8.37 total days of gabapentin prescribed per enrollee (95% confidence interval of - 10.34 to - 6.39). In contrast, PDMP regulation resulted in a reduction of 1.01 total days of gabapentin prescribed per enrollee (95% confidence interval of - 1.74 to - 0.29).

Classifying gabapentin as a Schedule V drug results in substantial reduction in total days prescribed whereas PDMP regulation results in modest reduction.