title: Cross-cultural adaptation and assessment of the reliability and validity of the Core Outcome Measures Index (COMI) for the Brazilian-Portuguese language.
abstract: OBJECTIVE
  The use of patient-orientated questionnaires is of utmost importance in assessing the outcome of spine surgery. Standardisation, using a common set of outcome measures, is essential to aid comparisons across studies/in registries. The Core Outcome Measures Index (COMI) is a short, multidimensional outcome instrument validated for patients with spinal disorders. This study aimed to produce a Brazilian-Portuguese version of the COMI.
  
  
  METHODS
  A cross-cultural adaptation of the COMI into Brazilian-Portuguese was carried out using established guidelines. 104 outpatients with chronic LBP (>3 months) were recruited from a Public Health Spine Medical Care Centre. They completed a questionnaire booklet containing the newly translated COMI, and other validated symptom-specific questionnaires: Oswestry Disability Index (ODI) and Roland Morris disability scale (RM), and a pain visual analogue scale. All patients completed a second questionnaire within 7-10 days to assess reproducibility.
  
  
  RESULTS
  The COMI summary score displayed minimal floor and ceiling effects. On re-test, the responses for each individual domain of the COMI were within 1 category in 98% patients for the domain 'function', 96% for 'symptom-specific well-being', 97% for 'general quality of life', 99% for 'social disability' and 100% for 'work disability'. The intraclass correlation coefficients (ICC(2,1)) for COMI pain and COMI summary scores were 0.91-0.96, which compared favourably with the corresponding values for the RM (ICC, 0.99) and ODI (ICC, 0.98). The standard error of measurement for the COMI was 0.6, giving a "minimum detectable change" (MDC95%) of approximately 1.7 points i.e., the minimum change to be considered "real change" beyond measurement error. The COMI scores correlated as hypothesised (Rho, 0.4-0.8) with the other symptom-specific questionnaires.
  
  
  CONCLUSIONS
  The reproducibility of the Brazilian-Portuguese version of the COMI was comparable to that of other language versions. The COMI scores correlated in the expected manner with existing but longer symptom-specific questionnaires suggesting good convergent validity for the COMI. The Brazilian-Portuguese COMI represents a valuable tool for Brazilian study-centres in future multicentre clinical studies and surgical registries.
authors.affiliation: Santa Casa e Asilo dos Pobres, Batatais, Brazil.
authors.forename: L H F
authors.initials: LH
authors.lastname: Damasceno
authors.forename: P A G
authors.initials: PA
authors.lastname: Rocha
authors.forename: E S
authors.initials: ES
authors.lastname: Barbosa
authors.forename: C A M
authors.initials: CA
authors.lastname: Barros
authors.forename: F T
authors.initials: FT
authors.lastname: Canto
authors.forename: H L A
authors.initials: HL
authors.lastname: Defino
authors.forename: A F
authors.initials: AF
authors.lastname: Mannion
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001938:Brazil; D003431:Cross-Cultural Comparison; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D007802:Language; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care / Q000379:methods*; D010147:Pain Measurement; D011594:Psychometrics; D015203:Reproducibility of Results; D013131:Spine / Q000601:surgery*; D011795:Surveys and Questionnaires; D014177:Translations