title: Validation of the Norwegian version ofHannover Functional Ability Questionnaire.
abstract: METHODS
  Cross-sectional and longitudinal designs within a prospective cohort study.
  
  
  OBJECTIVE
  Translation of Hannover Functional Ability Questionnaire (FFbH-R) into Norwegian and examination of its factor structure, internal consistency, reproducibility, construct validity, and responsiveness in patients with long-lasting back pain.
  
  
  BACKGROUND
  Several condition-specific instruments have been developed to evaluate functional status in low back pain, but FFbH-R was the only instrument found to solely measure perceived capability of performing daily activities.
  
  
  METHODS
  Recommended guidelines for translation of questionnaires and quality criteria for validation were followed. A total of 111 patients (aged 18-65 years) with long-lasting back pain were consecutively recruited from an outpatient spine clinic. Two additional samples of patients with long-lasting back pain were added into the exploratory factor analysis, giving a total number of 224 patients. Predefined hypotheses regarding construct and longitudinal validity (responsiveness) were examined.
  
  
  RESULTS
  Factor analysis indicated that 2 items should be removed, resulting in a 3-factor solution as the best fit. The factors were related to flexibility, dynamic strength, and posture endurance. Satisfactory internal consistency and reproducibility were demonstrated for the total and subscales of the Norwegian version of FFbH-R. Most of the predefined hypothesis regarding construct and longitudinal validity were confirmed, and discriminate ability was shown. Minor floor and ceiling effects were demonstrated.
  
  
  CONCLUSIONS
  Psychometric properties of the Norwegian version of FFbH-R were satisfactory in patients with long-lasting back pain, but the dynamic strength and posture endurance subscales might be complemented with additional items.
authors.affiliation: Uni Health, Bergen, Norway. liv.magnussen@uni.no
authors.forename: Liv Heide
authors.initials: LH
authors.lastname: Magnussen
authors.forename: Hildegunn
authors.initials: H
authors.lastname: Lygren
authors.forename: Bodil
authors.initials: B
authors.lastname: Anderson
authors.forename: Kyrre
authors.initials: K
authors.lastname: Breivik
authors.forename: Liv Inger
authors.initials: LI
authors.lastname: Strand
mesh_terms: D000203:Activities of Daily Living; D000293:Adolescent; D000328:Adult; D000368:Aged; D003431:Cross-Cultural Comparison; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D017116:Low Back Pain / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D009664:Norway; D011446:Prospective Studies; D011594:Psychometrics / Q000379:methods; D011788:Quality of Life; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires / Q000592:standards*; D055815:Young Adult