title: Validity of the French version of the Core Outcome Measures Index for low back pain patients: a prospective cohort study.
abstract: OBJECTIVE
  Among the many questionnaires available to evaluate low back pain (LBP) patients, the Core Outcome Measures Index (COMI) has the unique advantage to investigate five dimensions using seven short questions. The aim of this study was to explore additional properties of the questionnaire in a French-speaking non-surgical population.
  
  
  METHODS
  This study was conducted on 168 patients suffering from subacute or chronic LBP and followed up for 6 months in three French-speaking countries. In addition to basic psychometric properties (e.g., construct validity, floor and ceiling effect, reproducibility), internal validity was analyzed by a factor analysis using Cronbach's alpha. Responsiveness and sensitivity to change were assessed through minimal detectable change (MDC), effect size, and Minimal Clinically Important Improvement (MCII). We used an anchor-based method with receiver operating characteristic (ROC) curve analysis to assess MCII and the Patient Acceptable Symptom State.
  
  
  RESULTS
  Construct validity, reliability (Cronbach's alpha = 0.87), reproducibility and the absence of floor and ceiling effects were confirmed. Factor analysis indicated a one-dimensional construct that validates the use of a sum score. The MDC (2.1) was inferior to the MCII (2.3). The limit below which the patient claims to be in a fair condition (Patient Acceptable Symptom State) was set at 3.
  
  
  CONCLUSIONS
  The COMI is a self-report questionnaire with the capacity to easily and quickly explore several dimensions in patients with LBP that can be then summarized in a meaningful sum score. Additional knowledge provided by our study should encourage the widespread use of the COMI among the spine community.
authors.affiliation: Department of Rheumatology, University of Geneva Hospitals, 4 Rue Gabrielle Perret-Gentil, 1211, Geneva 14, Switzerland, stephane.genevay@hcuge.ch.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Genevay
authors.forename: Marc
authors.initials: M
authors.lastname: Marty
authors.forename: Delphine S
authors.initials: DS
authors.lastname: Courvoisier
authors.forename: Violaine
authors.initials: V
authors.lastname: Foltz
authors.forename: Geneviève
authors.initials: G
authors.lastname: Mahieu
authors.forename: Christophe
authors.initials: C
authors.lastname: Demoulin
authors.forename: Agnieszka Gierasimowicz
authors.initials: AG
authors.lastname: Fontana
authors.forename: Michael
authors.initials: M
authors.lastname: Norberg
authors.forename: Pierre
authors.initials: P
authors.lastname: de Goumoëns
authors.forename: Christine
authors.initials: C
authors.lastname: Cedraschi
authors.forename: Sylvie
authors.initials: S
authors.lastname: Rozenberg
mesh_terms: D000328:Adult; D004185:Disability Evaluation; D004651:Employment; D005260:Female; D006801:Humans; D007802:Language; D017116:Low Back Pain / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care / Q000592:standards*; D011446:Prospective Studies; D011594:Psychometrics / Q000379:methods / Q000592:standards*; D012372:ROC Curve; D015203:Reproducibility of Results; D057566:Self Report; D018582:Sick Leave; D011795:Surveys and Questionnaires / Q000592:standards*