Trends in Stimulant Pharmacotherapy and the Impact of the 2022 Shortage for Patients on Stable MedicationMaintenance Therapy in the United States

Background: Attention-deficit/hyperactivity disorder (ADHD) is a common neurodevelopmental condition affecting both children and adults, and stimulant medications are the most effective pharmacologic treatment for managing symptoms. Over the past decade, there has been substantial growth in ADHD diagnoses and stimulant prescribing in the United States, particularly among adults and females. At the same time, a national shortage of stimulant medications declared in October 2022 raised concerns about disruptions in treatment continuity for individuals who rely on consistent medication access. Limited research has quantified how these supply disruptions affected individuals receiving stable stimulant therapy. Objectives: This study aimed to examine long-term trends in stable stimulant medication use in the United States and to evaluate the population-level impact of the 2020 COVID-19 pandemic and the 2022 stimulant shortage on individuals receiving stable stimulant therapy. Specific aims were to (1) estimate trends from 2016 to 2024 in the rate of individuals with stable stimulant prescriptions, stratified by drug type (amphetamine, methylphenidate) and (2) assess whether these trends differed by patient age group and sex. Methods: This was a retrospective longitudinal analysis using the IQVIA all-payer longitudinal prescription claims database, representing more than 90% of United States retail prescription pharmacy fills from January 2016 through December 2024. The study population included individuals aged 5-64 years old with a stable stimulant prescription, defined as at least 12 months of continuous medication fills with the same drug type and medication supply on ≥80% of days (proportion of days covered ≥0.80). Monthly rates of individuals meeting the stable therapy definition were calculated per 100,000 United States population using US Census data. Trends were analyzed using joinpoint regression to identify statistically significant inflection points and estimate monthly percent changes, including Monthly Percent Change (MPC) and Average Monthly Percent Change (AMPC) estimates. Results: In 2016 the population rate of stable amphetamine prescription fills was 458 per 100,000 individuals, and in 2024 it was 791 per 100,000 individuals. For stable methylphenidate, in 2019 the rate was 201 per 100,000 individuals and concluded in December 2024 with 238 per 100,000 individuals. Overall from 2016-2024, the rate of stable amphetamine treatment (AMPC=0.51) grew at a faster pace than stable methylphenidate rates (AMPC=0.16). Increases in the rate of stable stimulant treatment were larger in females than males (amphetamine: female AMPC=0.61, male AMPC=0.39; methylphenidate: female AMPC=0.26, male AMPC=0.10). Age groups younger than 18 years had decreasing or flat rates of stable treatment between 2016-2024. Trends for the youngest groups (age 5-9 for amphetamine and 5-24 for methylphenidate) had no observed joinpoints. For amphetamine, school-aged children, 10-17 years, had significant positive rates prior to the COVID-19 pandemic (age 10-14 MPC=0.70; age 15-17 MPC=0.20), which inverted to a significant negative rate around the time of the pandemic (age 10-14 MPC=-1.31; age 15-17 MPC=-1.12), followed by a period of neither growth nor decline for several months, then proceeded to significantly decline again around the time of the stimulant shortage (age 10-14 MPC=-1.29; age 15-17 MPC=-1.40). Adult populations, driven by females, had a significant decline in stable stimulant prescriptions around the time of the Fall 2022 shortage, but have since rebounded in 2024 to pre-shortage rates. Conclusion: This study provides population-level evidence on long-term patterns in stable stimulant therapy and offers insight into whether recent health system events, such as including the COVID-19 pandemic and the national stimulant shortage, may have influenced continuity of care among individuals receiving long-term ADHD pharmacotherapy. Understanding these trends may help inform clinical practice, medication supply policies, and regulatory decisions aimed at ensuring reliable access to essential ADHD treatments in the event of future shortages.