A change in the trend in dosulepin usage following the introduction of a prescribing indicator but not after two national safety warnings

Summary What is known and objective The tricyclic antidepressant dosulepin has been associated with an increased risk of toxicity in overdose compared with other antidepressants. In the UK, the MHRA and NICE have issued advice on the prescribing of dosulepin, and a National Prescribing Indicator (NPI) to monitor usage was introduced in Wales in 2011. The aim of this study was to assess whether trends in dosulepin usage in Wales and NE England changed following the two pieces of safety guidance and the introduction of the National Prescribing Indicator in Wales. Methods Primary care dosulepin usage in the 12 months prior to and following MHRA safety advice (in 2007), NICE guideline CG90 (in 2009) and the introduction of the NPI (in 2011) was obtained. Usage was measured using defined daily doses (DDDs) per 1000 prescribing units (PUs). The trends in the 12 months prior to and following the introduction of prescribing advice and the NPI were compared using an autoregressive integrated moving average (ARIMA) model. Results and discussion In Wales, the trend in dosulepin usage did not change significantly prior to and following the MHRA advice: −0·18 and −0·43 DDDs/1000PUs per month, respectively (P = 0·07), or prior to and following NICE CG90: −0·30 and −0·49 DDDs/1000PUs per month, respectively (P = 0·35). In the 12 months prior to and following the introduction of the NPI, the trend was −0·45 and −0·98 DDDs/1000PUs per month, respectively (P = 0·001). In NE England, the trend did not alter significantly following the NICE advice or the introduction of the NPI in Wales. What is new and conclusion The trend in dosulepin usage in Wales altered significantly following the introduction of the NPI, but not after the other prescribing advice. This association, coupled with the absence of a significant change in NE England over the same period, provided some evidence of the effectiveness of the NPI in prompting a change in prescribing behaviour in Wales. The tricyclic antidepressant dosulepin has been associated with an increased risk of toxicity in overdose compared with other antidepressants. In the 12‐month period following the introduction of a National Prescribing Indicator, the trend in dosulepin usage in Wales decreased significantly compared with the previous year. This association, coupled with the absence of a significant change in NE England over the same period, provided some evidence of the effectiveness of the NPI in prompting a change in prescribing