Abstract
BACKGROUND: Attention-deficit/hyperactivity disorder (ADHD) is a heterogeneous condition with extensive psychiatric comorbidities. ADHD has been associated with substantial clinical and economic burden; however, little is known about the incremental burden specifically attributable to psychiatric comorbidities of ADHD in adults. OBJECTIVE: To assess the impact of psychiatric comorbidities, specifically anxiety and depression, on health care resource utilization (HRU) and costs in treated adults with ADHD in the United States. METHODS: A retrospective case-cohort study was conducted. Adults with ADHD were identified in the IQVIA PharMetrics Plus database (10/01/2015-09/30/2021). The index date was defined as the date of initiation of a randomly selected ADHD treatment. The baseline period was defined as the 6 months prior to the index date, and the study period as the 12 months following the index date. Patients with at least 1 diagnosis for anxiety and/or depression during both the baseline and study periods were classified in the ADHD+anxiety/depression cohort, whereas those without diagnoses for anxiety or depression at any time were classified in the ADHD-only cohort. Entropy balancing was used to create reweighted cohorts with similar baseline characteristics. All-cause HRU and health care costs were assessed during the study period and compared between cohorts using regression analyses. Cost analyses were also conducted in subgroups stratified by comorbid conditions. RESULTS: After reweighting, patients in the ADHD-only cohort (N = 276,906) and ADHD+anxiety/depression cohort (N = 217,944) had similar characteristics (mean age 34.1 years; 54.8% male). All-cause HRU was higher in the ADHD+anxiety/depression cohort than the ADHD-only cohort (incidence rate ratios for inpatient admissions: 4.5, emergency department visits: 1.8, outpatient visits: 2.0, and psychotherapy visits: 6.4; all P < 0.01). All-cause health care costs were more than 2 times higher in the ADHD+anxiety/depression cohort than the ADHD-only cohort (mean per-patient per-year [PPPY] costs in ADHD-only vs ADHD+anxiety/depression cohort: $5,335 vs $11,315; P < 0.01). Among the ADHD+anxiety/depression cohort, average all-cause health care costs were $9,233, $10,651, and $15,610 PPPY among subgroup of patients with ADHD and only anxiety, only depression, and both anxiety and depression, respectively. CONCLUSIONS: Comorbid anxiety and depression is associated with additional HRU and costs burden in patients with ADHD. Comanagement of these conditions is important and has the potential to alleviate the burden experienced by patients and the health care system.