Impact of schedule V controlled substance classification of gabapentin on adult gabapentin-involved overdose rates, West Virginia, 2016-2019: A controlled time series analysis.

OBJECTIVE

Assess the association between West Virginia's classification of gabapentin as a schedule V controlled substance and fatal overdoses involving gabapentin, relative to a control state.

METHODS

Using a controlled interrupted time series design, we modeled a segmented linear regression using Newey-West standard errors to estimate the immediate and trend changes in gabapentin-involved fatal overdoses among adults in West Virginia associated with gabapentin's scheduling in June 2018. Data from North Carolina (no gabapentin scheduling) was used as a control to account for potential secular changes. Quarterly rates were computed from 2016 to 2019.

RESULTS

The introduction of West Virginia's policy was associated with an immediate decrease in the rate of gabapentin-involved fatal overdoses (drop of 0.39 overdoses per 100,000 adults) in West Virginia relative to North Carolina (95% CI: -0.75, -0.03). There was no evidence to suggest a change in trend relative to North Carolina (0.02 overdoses per 100,000 adults per quarter; 95% CI: -0.06, 0.10).

CONCLUSIONS

Classifying gabapentin as a schedule V controlled substance was associated with an immediate decrease in the rate of gabapentin-involved fatal overdoses in West Virginia, relative to North Carolina.

POLICY IMPLICATIONS: Combined with broader efforts to address overdose deaths, scheduling gabapentin is a potential supply-side intervention that may contribute to reductions in gabapentin involvement in fatal overdoses.