A psychometric investigation of fear-avoidance model measures in patients with chronic low back pain

Abstract

Study design: Validity and test-retest reliability of questionnaires related to the fear-avoidance model (FAM).

Objective: To investigate test-retest reliability, construct redundancy, and criterion validity for 4 commonly used FAM measures.

Background: Few studies have reported psychometric properties for more than 2 FAM measures within the same cohort, making it difficult to determine which specific measures should be implemented in outpatient physical therapy settings.

Methods: Fifty-three consecutive patients (mean age, 44.3 + or - 18.5 years) with chronic low back pain participated in this study. Data were collected with validated measures for FAM constructs, including the Fear-Avoidance Beliefs Questionnaire (FABQ), Fear of Pain Questionnaire (FPQ), Tampa Scale for Kinesiophobia, and Pain Catastrophizing Scale. Validated measures were used to investigate criterion validity of the FAM measures, including the Patient Health Questionnaire for depression, the numerical rating scale for pain intensity, the Physical Impairment Scale for physical impairment, and the Oswestry Disability Questionnaire for self-report of disability. Test-retest reliability of the FAM measures was determined with intraclass correlation coefficients (ICC2,1) for total questionnaire scores at baseline and 48 hours later. Construct redundancy was determined with Pearson correlation coefficients for FAM measures. Criterion validity was assessed by 4 separate multiple regression models that included age, sex, and employment status as covariates. Depression, pain intensity, physical impairment, and disability were the dependent variables for these analyses.

Results: Test-retest ICC coefficients ranged from 0.90 to 0.96 for all FAM questionnaires. The FAM measures were significantly correlated with each other, with the only exception being that the FPQ was not correlated with the FABQ work scale. In the multiple regression models, the Pain Catastrophizing Scale contributed additional variance to depression. The FABQ physical activity scale contributed additional variance to pain intensity and disability. The FABQ work scale contributed additional variance to physical impairment and disability. No other FAM measures contributed to these regression models.

Conclusion: These data suggest that 4 commonly used FAM measures have similar test-retest reliability, with varying amounts of construct redundancy. The criterion validity analyses suggest that measurement of fear-avoidance constructs for patients seeking outpatient physical therapy with chronic low back pain should include the Pain Catastrophizing Scale and the FABQ.