title: Validation of expert opinion in identifying comorbidities associated with atopic dermatitis/eczema.
abstract: BACKGROUND
  The use of expert opinion is widespread in economic studies of healthcare utilisation; however, few studies have attempted to assess the validity of assumptions derived from such sources.
  
  
  OBJECTIVE
  To examine the use of such expert opinion in determining comorbidities associated with atopic dermatitis/eczema (AD/E), which were assessed as part of a recent third-party payer cost-of-illness study.
  
  
  METHODS
  To identify the disease-related comorbidities that would represent costs associated with AD/E, physicians on an expert panel were asked individually and then collectively to group all International Classification of Diseases, 9(th) Edition-Clinical Modification (ICD-9-CM) diagnosis codes as 'most likely', 'possibly' or 'definitely not' related to the costs of identifying and treating patients with AD/E. Claims representing $US464 million in payer reimbursements from nearly 125 000 patients with AD/E were identified within two separate claims databases (1997 values). Over 850 ICD-9-CM diagnosis codes were identified in the first-listed position from these claims. For each group of 'most likely', 'possibly' and 'definitely not' related diagnosis codes, prevalence rates were compared within AD/E and non-AD/E populations from the two historical payer claims databases. Adjusted and non-adjusted odds ratios were calculated by comparing prevalence rates between AD/E and non-AD/E patients in the same payer population.
  
  
  RESULTS
  The mean prevalence rate of any diagnosis code in the AD/E population was 0.65 +/- 1.82% (SD) with a mean odds ratio of 1.81 +/- 0.96. Comorbidities considered by the expert panel 'most likely' to be associated with AD/E had higher prevalence rates (3.28 +/- 3.63%) and odds ratios (2.14 +/- 1.14). Comorbidities considered to be 'possibly' related to AD/E had prevalence rates and odds ratios of 3.01 +/- 5.06% and 1.84 +/- 0.82, respectively. Comorbidities considered to be 'definitely not' related to AD/E had the lowest prevalence rates (0.45 +/- 1.09%) and odds ratios (1.80 +/- 0.97).
  
  
  CONCLUSIONS
  Comparing the result of consensus panels with actual claims histories validated the use of expert opinion in determining comorbidities associated with AD/E. Expert opinion yielded valid results in terms of identifying comorbidities that manifested frequently and disproportionately in the AD/E population. Limited statistical measurements of comorbidities would have been less specific than expert opinion. Future cost-of-illness studies should consider alternative data sources and methodologies to enhance the validity and importance of expert opinion and to corroborate their findings.
authors.affiliation: Department of Dermatology, University of Michigan Medical School and Veterans Administration Medical Center, Ann Arbor, Michigan, USA.
authors.forename: Charles N
authors.initials: CN
authors.lastname: Ellis
authors.forename: Lynn A
authors.initials: LA
authors.lastname: Drake
authors.forename: Mary M
authors.initials: MM
authors.lastname: Prendergast
authors.forename: William
authors.initials: W
authors.lastname: Abramovits
authors.forename: Mark
authors.initials: M
authors.lastname: Boguniewicz
authors.forename: C Ralph
authors.initials: CR
authors.lastname: Daniel
authors.forename: Mark
authors.initials: M
authors.lastname: Lebwohl
authors.forename: Seth R
authors.initials: SR
authors.lastname: Stevens
authors.forename: Diane L
authors.initials: DL
authors.lastname: Whitaker-Worth
authors.forename: Kuo B
authors.initials: KB
authors.lastname: Tong
mesh_terms: D015897:Comorbidity; D017281:Cost of Illness; D003876:Dermatitis, Atopic / Q000175:diagnosis / Q000191:economics* / Q000453:epidemiology; D004485:Eczema / Q000175:diagnosis / Q000191:economics* / Q000453:epidemiology; D017048:Health Care Costs; D006296:Health Services / Q000191:economics / Q000706:statistics & numerical data; D006801:Humans; D007349:Insurance, Health, Reimbursement / Q000191:economics; D016017:Odds Ratio; D014481:United States