Rescheduling gabapentinoids had negligible effects on prescribing behaviour by general practitioners in England

Abstract

Purpose: To determine whether the rescheduling of gabapentinoids in England as Schedule 3 Controlled Substances in April 2019, changed prescribing behaviour for gabapentinoids by general practitioners. Methods: Data on the monthly number of prescription items and the monthly average dose per prescription item were analysed for the period April 2017 to April 2021 under three models: (i) a simple linear regression, (ii) a linear spline with a knot at April 2019, and (iii) a parallel slopes model with time before and after the rescheduling as a covariate. Best fit models were selected based on them having the lowest corrected Akaike's information criterion. Auto-regressive integrated moving average (ARIMA) models were also generated. Results: For gabapentin, the best fit model for the number of prescription items was the simple linear model, and for the dose per prescription item it was the parallel slopes model. For pregabalin, the best fit model was the linear spline for the number of prescription items and the dose per prescription item. For all models, the interval estimates for the slopes were consistent with no change or no meaningful change in prescribing behaviour after April 2019. Forecasts from ARIMA models for gabapentin and pregabalin were consistent with no change in the number of prescription items per month. However, forecasts for the dose per prescription item for gabapentin or pregabalin did not fully capture the post-April 2019 trajectories. Conclusion: The reclassification of gabapentinoids did not materially change the prescribing behaviour of these drugs by general practitioners in England.