title: Domain-specific transition questions demonstrated higher validity than global transition questions as anchors for clinically important improvement.
abstract: OBJECTIVE
  Estimates of minimal clinically important differences in health measures may be affected by the anchor used. We examined if domain-specific transition questions had higher construct validity than global health transition questions as anchors for measures in a given domain.
  
  
  METHODS
  In a prospective study of 249 patients with rheumatoid arthritis, we examined changes in pain, physical function, joint swelling, stiffness, fatigue, and depression with treatment. We related these changes to a domain-specific transition question, global arthritis transition question, and the Short Form-36 (SF-36) health transition item.
  
  
  RESULTS
  Changes in all six clinical measures were more highly correlated with the domain-specific transition questions than with the global arthritis question and SF-36 transition question. Discrimination between patients who improved or not was also better using domain-specific questions. Estimates of minimal clinically important improvement (MCII) differed with the anchor when these were based on mean changes. MCII estimates from receiver operating characteristic curve analysis were not influenced by the choice of anchor when anchors had high agreement.
  
  
  CONCLUSIONS
  Domain-specific transition questions had higher construct validity as anchors for determining clinically important differences in health measures focused on a single domain than either global disease or general health transition questions.
authors.affiliation: Intramural Research Program, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, 10 Center Drive, Bethesda, MD 20819, USA. Electronic address: wardm1@mail.nih.gov.
authors.forename: Michael M
authors.initials: MM
authors.lastname: Ward
authors.affiliation: Intramural Research Program, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, 10 Center Drive, Bethesda, MD 20819, USA.
authors.forename: Lori C
authors.initials: LC
authors.lastname: Guthrie
authors.affiliation: Intramural Research Program, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, 10 Center Drive, Bethesda, MD 20819, USA.
authors.forename: Maria
authors.initials: M
authors.lastname: Alba
mesh_terms: D018771:Arthralgia / Q000453:epidemiology*; D001172:Arthritis, Rheumatoid / Q000453:epidemiology*; D015897:Comorbidity; D016001:Confidence Intervals; D003863:Depression / Q000453:epidemiology; D005221:Fatigue / Q000453:epidemiology; D005260:Female; D019456:Health Transition; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care / Q000379:methods*; D010147:Pain Measurement; D011446:Prospective Studies; D058996:Quality Improvement / Q000458:organization & administration / Q000706:statistics & numerical data*; D011788:Quality of Life; D012372:ROC Curve; D011795:Surveys and Questionnaires / Q000592:standards*
keywords: Anchor-based methods; Clinically important difference; Outcome measures; Pain; Physical function; Rheumatoid arthritis; Transition questions