title: Psychiatric comorbidity as predictor of costs in back pain patients undergoing disc surgery: a longitudinal observational study.
abstract: BACKGROUND
  Psychiatric comorbidity is common in back pain patients undergoing disc surgery and increases economic costs in many areas of health. The objective of this study was to analyse psychiatric comorbidity as predictor of direct and indirect costs in back pain patients undergoing disc surgery in a longitudinal study design.
  
  
  METHODS
  A sample of 531 back pain patients was interviewed after an initial disc surgery (T0), 3 months (T1) and 15 months (T2) using the Composite International Diagnostic Interview to assess psychiatric comorbidity and a modified version of the Client Sociodemographic and Service Receipt Inventory to assess resource utilization and lost productivity for a 3-month period prior interview. Health care utilization was monetarily valued by unit costs and productivity by labour costs. Costs were analysed using random coefficient models and bootstrap techniques.
  
  
  RESULTS
  Psychiatric comorbidity was associated with significantly (p < 0.05) increased direct (+664 Euro) and indirect costs (+808 Euro) at T0. The direct cost difference predominantly resulted from medical health care utilization and was nearly unchanged at T2. Further important cost predictors were clinical variables like the presence of chronic medical disease, the number of previous disc surgeries, and time and gender.
  
  
  CONCLUSIONS
  Psychiatric comorbidity presents an important predictor of direct and indirect costs in back pain patients undergoing disc surgery, even if patients do not utilize mental health care. This effect seems to be stable over time. More attention should be given to psychiatric comorbidity and cost-effective treatments should be applied to treat psychiatric comorbidity in back pain patients undergoing disc surgery to reduce health care utilization and costs associated with psychiatric comorbidity.
authors.affiliation: Department of Medical Sociology and Health Economics, University Medical Centre Hamburg-Eppendorf, Hamburg, Germany. a.konnopka@uke.de
authors.forename: Alexander
authors.initials: A
authors.lastname: Konnopka
authors.forename: Margrit
authors.initials: M
authors.lastname: Löbner
authors.forename: Melanie
authors.initials: M
authors.lastname: Luppa
authors.forename: Dirk
authors.initials: D
authors.lastname: Heider
authors.forename: Sven
authors.initials: S
authors.lastname: Heinrich
authors.forename: Steffi
authors.initials: S
authors.lastname: Riedel-Heller
authors.forename: Hans Jörg
authors.initials: HJ
authors.lastname: Meisel
authors.forename: Lutz
authors.initials: L
authors.lastname: Günther
authors.forename: Jürgen
authors.initials: J
authors.lastname: Meixensberger
authors.forename: Hans-Helmut
authors.initials: HH
authors.lastname: König
mesh_terms: D000328:Adult; D001416:Back Pain / Q000175:diagnosis / Q000191:economics* / Q000453:epidemiology; D016009:Chi-Square Distribution; D015897:Comorbidity; D017046:Cost Savings; D003362:Cost-Benefit Analysis; D005260:Female; D017048:Health Care Costs; D006801:Humans; D007405:Intervertebral Disc Displacement / Q000175:diagnosis / Q000191:economics / Q000453:epidemiology / Q000601:surgery*; D008137:Longitudinal Studies; D008297:Male; D001523:Mental Disorders / Q000175:diagnosis / Q000191:economics* / Q000453:epidemiology; D018803:Models, Economic; D019637:Orthopedic Procedures / Q000009:adverse effects / Q000191:economics*; D010149:Postoperative Pain / Q000175:diagnosis / Q000191:economics* / Q000453:epidemiology; D015995:Prevalence; D018570:Risk Assessment; D012307:Risk Factors; D011795:Surveys and Questionnaires; D013997:Time Factors; D016896:Treatment Outcome