Design: A prospective cohort study with 2 groups.
Patients: The questionnaire was tested in 123 patients with acute low back pain and 50 patients with chronic low back pain.
Methods: A translation and cross-cultural adaptation was performed. Test-retest reliability was assessed in 28 patients with chronic low back pain. Responsiveness was assessed in acute low back pain.
Results: Two factors for the FABQ were confirmed; fear-avoidance beliefs about work (FABQ–Work) and physical activity (FABQ–PA), accounting for 60% and 54% of the total variance in acute and chronic low back pain, respectively. For FABQ–Work and FABQ–PA internal consistency was 0.90 and 0.79, intra-class correlation coefficients 0.82 and 0.66, minimal detectable changes 12 and 9 points, and coefficients of variation were 16% and 23%. The FABQ correlated weakly to moderately with pain, disability, distress, and clinical variables. Standardized response means were low for FABQ–Work (0.32) and moderate (0.56) for FABQ–PA. Both FABQ subscales showed initially floor and/or ceiling effects.
Conclusion: The Norwegian FABQ version had acceptable factor structure, internal consistency, test-retest reliability and construct validity. The responsiveness of the FABQ–Work was low, and for the FABQ–PA moderate, in the acute sample.