3C-10 - Impact of National Patient Safety Alert after Attention Deficit Hyperactivity Disorder Medication Supply Shortage in England: a Repeated Cross-Sectional Study

Background: Patients with Attention Deficit Hyperactivity Disorder (ADHD) need regular treatment. The United Kingdom faced a supply shortage of ADHD-related medications, including lisdexamfetamine, guanfacine, and products of long-acting methylphenidate, starting from early 2023 and issued a national patient safety alert in September 2023.

Objectives: This study aims to summarize and investigate the change in ADHD medication dispensing in primary care in England after the announcement of a national patient safety alert due to medication supply shortage.

Methods: We leveraged English prescribing data, an official database covering monthly dispensing from general practitioner prescriptions in England, with a study period from September 2019 to August 2024. Practices prescribing any ADHD medication were included and ADHD medications were identified based on British National Formulary codes. The monthly number of Defined Daily Doses (DDDs) of each substance was quantified and analyzed using interrupted time series analysis to identify changes in levels and trends in September 2023, represented by coefficients β2 and β3, respectively. Joinpoint trend analysis software was used to identify the breaks, where trends of monthly number DDDs shifted significantly.

Results: The level of monthly DDDs of methylphenidate still increased (β2= 285,991.3, p= 0.003) in September 2023, but exhibited a downward trend (β3= -68,835.9, p< 0.001) after the launch of a national patient safety alert. The level of monthly DDDs of lisdexamfetamine decreased (β2= -622,381.0, p< 0.001) while showing an upward trend (β3= 17,984.9, p< 0.001) after September 2023. Similarly, the level of monthly DDDs of guanfacine decreased (β2= -24,684.9, p< 0.001), with no long-term effect on the trend change. As an alternative first-line treatment, the level of monthly DDDs of dexamfetamine increased (β2= 22,999.7, p= 0.018) immediately in September 2023. However, there’s no significant increase in the trend of monthly DDDs of short-acting methylphenidate (β3= 1,972.3, p= 0.091) while the trend of long-acting methylphenidate declined (β3= -71,283.2, p< 0.001). Joinpoint analysis revealed that, apart from methylphenidate, downward trends of monthly DDDs of lisdexamfetamine and guanfacine occurred prior to the national patient safety alert in September 2023.

Conclusions: The medication supply shortage had immediate and long-term impacts on the prescription of ADHD medications with potential substitutional effects, and changes in prescription could occur before the launch of the national patient safety alert. Further research is needed to investigate the clinical implications of medication shortages on disease control in ADHD patients.