ADHD Diagnosis and Timing of Medication Initiation Among Children Aged 3 to 5 Years.

Importance: Early identification and treatment of attention-deficit/hyperactivity disorder (ADHD) symptoms in preschool-age children is important for mitigating social, emotional, and academic problems. Clinical practice guidelines recommend first-line behavior intervention before considering medication treatment for children aged 4 to 5 years. Objective: To assess variation in rates of ADHD identification and rates and timing of medication initiation in children aged 3 to 5 years in primary care settings across 8 US pediatric health systems and to identify patient factors associated with the time from diagnosis to prescription. Design, Setting, and Participants: This retrospective cohort study used electronic health records from primary care clinics affiliated with 8 academic institutions participating in the PEDSnet Clinical Research Network. Participants were children aged 3 to 5 years seen between 2016 to 2023. Data were extracted from the PEDSnet database on April 18, 2025. Exposure: ADHD diagnosis at age 4 to 5 years. Main Outcomes and Measures: The primary outcomes were (1) rate of ADHD diagnosis, (2) rate of stimulant and nonstimulant prescription after diagnosis before age 7 years, and (3) time from first ADHD-related diagnosis (including symptom-level diagnoses) to medication prescription. Independent variables included institution, year of diagnosis, patient age, sex, race and ethnicity, medical insurance, and presence of comorbidities. Multivariable Cox proportional hazards models were used to estimate associations between clinical and demographic variables and time from diagnosis to prescription. Results: Of 712 478 children seen in primary care at age 3 to 5 years, 9708 (1.4%) received an ADHD diagnosis at age 4 to 5 years (range across institutions, 0.5%-3.1%; median [IQR] age at first ADHD-related diagnosis, 5.31 [4.86-5.66] years). Of those with ADHD, 7414 (76.4%) were male, 1762 (18.1%) were Hispanic, 122 (1.3%) were non-Hispanic Asian, 3014 (31.0%) were non-Hispanic Black, 479 (4.9%) were non-Hispanic multiracial, 3782 (39.0%) were non-Hispanic White, 148 (1.5%) were non-Hispanic other, and 401 (4.1%) were of unknown race and ethnicity. Of 9708 preschool-age children with ADHD, 6624 (68.2%) were prescribed ADHD medications before age 7 years, and 4092 (42.2%) were prescribed medications within 30 days of the first documentation of an ADHD-related diagnosis (range across institutions, 26.0%-49.0%). Asian (adjusted hazard ratio [aHR], 0.51; 95% CI, 0.38-0.68), Hispanic (aHR, 0.75; 95% CI, 0.70-0.81), and Black (aHR, 0.88; 95% CI, 0.83-0.94) children with ADHD were less likely to be prescribed medication early compared with White children. Older vs younger patients (aHR, 1.62; 95% CI, 1.55-1.69), male vs female patients (aHR, 1.17; 95% CI, 1.11-1.25), and publicly insured vs privately insured patients (aHR, 1.09; 95% CI, 1.03-1.15) were more likely to be prescribed medication early. Conclusion and Relevance: In this retrospective cohort study of preschool-age children with ADHD seen in primary care in 8 large pediatric health systems, many children were prescribed medications at or shortly after the first documented diagnosis. Analysis of clinical documentation is needed to understand early prescription patterns.