title: Impact of mental health comorbidities on health care utilization and expenditure in a large US managed care adult population with ADHD.
abstract: OBJECTIVE
  To estimate the health resource use (HRU) and expenditure of adult patients with attention deficit/hyperactivity disorder (ADHD) subsequently diagnosed with one or more mental health (MH) comorbidities.
  
  
  METHODS
  Using Kaiser Permanente Southern California electronic medical records (January 1, 2006, to December 31, 2009), we identified adults with at least one ADHD diagnosis and at least two subsequent prescriptions fills for ADHD medication. The date of first MH comorbidity diagnosis after the index ADHD diagnosis was defined as the index transition date. Continuous eligibility 12 months before and after the index transition date was required. For patients with multiple transitions (≥2), the post-transition period reflected the 12 months after the second transition. HRU for all-cause inpatient, outpatient, emergency department, behavioral therapy, overall prescription fill counts, and ADHD-specific prescription fill counts and mean patient expenditure (2010 US $) were estimated. Generalized estimating equations were used to evaluate differences in HRU and expenditure between the pre- and post-transition periods, respectively.
  
  
  RESULTS
  Of the 3809 patients with ADHD identified, 989 (26%) had at least one transition (n = 357 single and n = 632 multiple). From the pre- to the post-transition period, for single transition cohort, all HRU increased significantly except for behavioral therapy. In the multiple transition cohort, all HRU increased significantly. Total expenditure increased by mean ± SE of $1822 ± $306 and $4432 ± $301 (both P < 0.0001) in the single and multiple transition cohorts, respectively.
  
  
  CONCLUSIONS
  Twenty-six percent of patients with ADHD transitioned to MH comorbid diagnoses. Increased HRU and expenditure were associated with MH transitions. Identifying of patients with ADHD at risk for MH comorbidities may help to improve their outcomes.
authors.affiliation: Kaiser Permanente Southern California, Pasadena, CA, USA. Electronic address: aniket.a.kawatkar@kp.org.
authors.forename: Aniket A
authors.initials: AA
authors.lastname: Kawatkar
authors.affiliation: Leonard D. Schaeffer Center for Health Policy and Economics, University of Southern California, Los Angeles, CA, USA.
authors.forename: Tara K
authors.initials: TK
authors.lastname: Knight
authors.affiliation: Southern California Permanente Medical Group, Woodland Hills, CA.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Moss
authors.affiliation: Shire, Development LLC Wayne, PA, USA.
authors.forename: Vanja
authors.initials: V
authors.lastname: Sikirica
authors.affiliation: Kaiser Permanente Southern California, Pasadena, CA, USA.
authors.forename: Li-Hao
authors.initials: LH
authors.lastname: Chu
authors.affiliation: Shire, Development LLC Wayne, PA, USA.
authors.forename: Paul
authors.initials: P
authors.lastname: Hodgkins
authors.affiliation: Shire, Development LLC Wayne, PA, USA.
authors.forename: M
authors.initials: M
authors.lastname: Haim Erder
authors.affiliation: Leonard D. Schaeffer Center for Health Policy and Economics, University of Southern California, Los Angeles, CA, USA.
authors.forename: Michael B
authors.initials: MB
authors.lastname: Nichol
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001289:Attention Deficit Disorder with Hyperactivity / Q000191:economics* / Q000453:epidemiology* / Q000523:psychology; D002140:California / Q000453:epidemiology; D015331:Cohort Studies; D015897:Comorbidity; D005260:Female; D005102:Health Expenditures / Q000639:trends; D006801:Humans; D008297:Male; D008329:Managed Care Programs / Q000191:economics* / Q000639:trends; D008603:Mental Health / Q000191:economics* / Q000639:trends; D008875:Middle Aged; D010342:Patient Acceptance of Health Care / Q000523:psychology; D011159:Population Surveillance / Q000379:methods; D012189:Retrospective Studies; D014481:United States / Q000453:epidemiology; D055815:Young Adult
keywords: ADHD; comorbidity; expenditure; mental health; utilization