Comorbidities and costs of adult patients diagnosed with attention-deficit hyperactivity disorder

Introduction: The purpose of this retrospective study was to examine the prevalence of comorbidities, resource use, direct medical costs, and the costs associated with missed work for adults diagnosed with attention-deficit hyperactivity disorder (ADHD). Study design: From a large claims database that captures inpatient, outpatient and prescription drug services, individuals diagnosed with ADHD between the years 1999 and 2001 were retrospectively identified. The ADHD cohort (n = 2252) were matched with a non-ADHD cohort (n = 2252) on a 1___1 ratio, based upon age, gender, metropolitan statistical area and type of insurance coverage. The ADHD cohort was compared with the non-ADHD cohort for differences in comorbidities and direct medical costs (inpatient, outpatient and prescription drug costs) using year 2001 prices. Using data from six Fortune 200 employers, time missed from work and costs associated with absenteeism, short-term disability and worker's compensation was examined for a subsample (n = 354) of the employees diagnosed with ADHD. Chi-square and t-statistics were used to compare the ADHD population with the control group with regards to comorbidites and service use. Analysis of covariance and multivariate regressions were used to examine differences in days missed from work, direct medical costs and costs associated with missed work. Results: Adults diagnosed with ADHD were significantly more likely to have a comorbid diagnosis of asthma (p = 0.0014), anxiety (p