Health system utilization before age 1 among children later diagnosed with autism or ADHD.

Children with autism spectrum disorder (ASD) or attention deficit hyperactivity disorder (ADHD) have 2-3 times increased healthcare utilization and annual costs once diagnosed, but little is known about their utilization patterns early in life. Quantifying their early health system utilization could uncover condition-specific health trajectories to facilitate earlier detection and intervention. Patients born 10/1/2006-10/1/2016 with ≥ 2 well-child visits within the Duke University Health System before age 1 were grouped as ASD, ADHD, ASD + ADHD, or No Diagnosis using retrospective billing codes. An additional comparison group was defined by later upper respiratory infection diagnosis. Adjusted odds ratios (AOR) for hospital admissions, procedures, emergency department (ED) visits, and outpatient clinic encounters before age 1 were compared between groups via logistic regression models. Length of hospital encounters were compared between groups via Mann-Whitney U test. In total, 29,929 patients met study criteria (ASD N = 343; ADHD N = 1175; ASD + ADHD N = 140). ASD was associated with increased procedures (AOR = 1.5, p < 0.001), including intubation and ventilation (AOR = 2.4, p < 0.001); and outpatient specialty care, including physical therapy (AOR = 3.5, p < 0.001) and ophthalmology (AOR = 3.1, p < 0.001). ADHD was associated with increased procedures (AOR = 1.41, p < 0.001), including blood transfusion (AOR = 4.7, p < 0.001); hospital admission (AOR = 1.60, p < 0.001); and ED visits (AOR = 1.58, p < 0.001). Median length of stay was increased after birth in ASD (+ 6.5 h, p < 0.001) and ADHD (+ 3.8 h, p < 0.001), and after non-birth admission in ADHD (+ 1.1 d, p < 0.001) and ASD + ADHD (+ 2.4 d, p = 0.003). Each condition was associated with increased health system utilization and distinctive patterns of utilization before age 1. Recognizing these patterns may contribute to earlier detection and intervention.