title: Differential impact of mental health multimorbidity on healthcare costs in diabetes.
abstract: OBJECTIVE
  This study assessed the prevalence and specific costs associated with discrete multimorbid mental health disease clusters in adults with diabetes mellitus (DM).
  
  
  METHODS
  Longitudinal analysis of a retrospective cohort.
  
  
  METHODS
  We performed a 5-year longitudinal analysis of a retrospective cohort of 733,071 patients with DM from the US Veterans Health Administration (VHA) between 2002 and 2006. The mental health comorbidities (MHCs) examined included depression, substance abuse, and psychosis. Our primary outcomes of interest were total inpatient, outpatient, and pharmacy costs measured in 2012 US$ from the perspective of the VHA.
  
  
  RESULTS
  DM was present with comorbid depression, substance abuse, and psychosis in 12.1%, 3.7%, and 4.2% of patients, respectively. Overall, 13.5% of patients had 1 MHC, 2.5% had 2 MHCs, and 0.5% had all MHCs. Total inpatient ($1,435,651,415), outpatient ($366,137,435), and pharmacy ($90,064,725) costs were highest for patients with DM and comorbid depression alone. At the per-patient level, DM plus psychosis and substance abuse had the highest inpatient costs ($35,518), DM plus all MHCs had the highest outpatient costs ($6962), and DM plus depression and psychosis had the highest pharmacy costs ($1753).
  
  
  CONCLUSIONS
  DM with comorbid depression is the most prevalent MHC combination and is associated with the highest total VHA healthcare costs. However, other comorbidity clusters are associated with higher mean per patient costs, and may therefore benefit from more intensive intervention. Analysis of healthcare expenditures by multimorbid disease clusters can be a useful tool for healthcare policy planning.
authors: Center for Health Disparities Research, Medical University of South Carolina-135 Rutledge Ave, Rm 280H, PO Box 250593 Charleston, SC 29425-0593. E-mail: egedel@musc.edu.
authors: Leonard E
authors: LE
authors: Egede
authors: Mulugeta
authors: M
authors: Gebregziabher
authors: Yumin
authors: Y
authors: Zhao
authors: Clara E
authors: CE
authors: Dismuke
authors: Rebekah J
authors: RJ
authors: Walker
authors: Kelly J
authors: KJ
authors: Hunt
authors: R Neal
authors: RN
authors: Axon
mesh_terms: D000368:Aged; D015331:Cohort Studies; D015897:Comorbidity; D003920:Diabetes Mellitus / Q000191:economics* / Q000453:epidemiology*; D005260:Female; D017048:Health Care Costs / Q000706:statistics & numerical data*; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D001523:Mental Disorders / Q000453:epidemiology*; D008875:Middle Aged; D012189:Retrospective Studies; D014481:United States / Q000453:epidemiology; D014493:United States Department of Veterans Affairs