Objective: to investigate select psychometric properties of fear-avoidance model measures commonly used to assess pain-related fear and catastrophizing in clinical studies of low back pain.
Methods: a convenience sample was recruited from patients (n=80) seeking outpatient physical therapy for low back pain. All patients completed self-report questionnaires for pain-related fear [Fear-avoidance Beliefs Questionnaire-physical activity (FABQ-PA), FABQ-work scale (W), and Tampa Scale for Kinesiophobia -11] and pain catastrophizing (PCS) at initial evaluation session. Patients also completed clinical measures for pain intensity (numerical rating scale) and self-report of disability (Oswestry Disability Index) at the initial evaluation session. Construct redundancy of the fear-avoidance questionnaires was assessed by factor analysis for individual items and Pearson correlation for total questionnaire scores. Concurrent validity was investigated with multiple regression models for pain intensity and disability.
Results: item analysis indicated all PCS and FABQ-W items loaded on 2 separate factors. The FABQ-PA and Tampa Scale for Kinesiophobia-11 loaded together on a third factor. As expected, all of the fear-avoidance questionnaires were significantly correlated with each other to varying degrees (rs ranged from 0.28 to 0.55, P<0.05 for all). In the multiple regression models only the FABQ-PA and PCS contributed unique variance to pain intensity and disability measures. Further analysis indicated the PCS mediated the relationship of the FABQ-PA by weakening its association with pain intensity and disability.
Discussion: these analyses suggest clinical assessment of the Fear-Avoidance Model of Musculoskeletal Pain likely captures 3 factors including PCS, beliefs about work, and beliefs about physical activity. The FABQ-PA and PCS can be recommended for clinical use because of their unique associations with pain intensity and disability. The FABQ-W may only be appropriate for those interested in assessing work specific beliefs.