title: Content validation of two SF-36 subscales for use in type 2 diabetes and non-dialysis chronic kidney disease-related anemia.
abstract: OBJECTIVE
  This study aimed to evaluate the relevance and importance of two SF-36 subscales, Vitality (VT) and Physical Function (PF), to assess concepts of energy and physical function in patients with type 2 diabetes mellitus (DM) and non-dialysis CKD-related anemia.
  
  
  METHODS
  Patients with clinical history of DM and non-dialysis CKD-related anemia (n = 68) were identified as follows: 40 participated in concept elicitation (CE) interviews; 20 in cognitive interviews (CI), and 8 in pilot interviews. Relevance and importance ratings for SF-36 VT and PF items were obtained. Interviews were recorded, transcribed, and patient expressions of concepts coded. Inter-rater agreement was used to evaluate coding consistency. Concepts elicited were mapped to SF-36 VT and PF items.
  
  
  RESULTS
  Patients (n = 64) were 65.6% women, 42.2% Caucasian, with mean age of 66.1 ± 11.6 years. Of 830 coded concepts, 388 (47%) were "Energy" expressions and 287 (35%) were "PF limitations" expressions. Low energy was reported by 85% patients and rated as an important limitation by 88%. Limitations in PF were reported by 56-82% patients and rated important by 44-96%. CE and CI quotes correspond well to SF-36 VT and PF items.
  
  
  CONCLUSIONS
  SF-36 VT and PF contents were suitable for assessing energy and physical function limitations, respectively, in this patient population.
authors.affiliation: Health Research Associates, Seattle, WA 98043, USA. martin@hrainc.net
authors.forename: Mona L
authors.initials: ML
authors.lastname: Martin
authors.forename: Donald L
authors.initials: DL
authors.lastname: Patrick
authors.forename: Shravanthi R
authors.initials: SR
authors.lastname: Gandra
authors.forename: Antonia V
authors.initials: AV
authors.lastname: Bennett
authors.forename: Nancy K
authors.initials: NK
authors.lastname: Leidy
authors.forename: Allen R
authors.initials: AR
authors.lastname: Nissenson
authors.forename: Fredric O
authors.initials: FO
authors.lastname: Finkelstein
authors.forename: Eldrin F
authors.initials: EF
authors.lastname: Lewis
authors.forename: Albert W
authors.initials: AW
authors.lastname: Wu
authors.forename: John E
authors.initials: JE
authors.lastname: Ware
mesh_terms: D000203:Activities of Daily Living; D000368:Aged; D000740:Anemia / Q000209:etiology; D015897:Comorbidity; D003430:Cross-Sectional Studies; D003924:Diabetes Mellitus, Type 2 / Q000453:epidemiology; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D008297:Male; D008875:Middle Aged; D011788:Quality of Life; D051436:Renal Insufficiency, Chronic / Q000150:complications / Q000453:epidemiology; D015203:Reproducibility of Results