Development and Validation of a Pain Behavior Assessment in Patients with Chronic Low Back Pain

High levels of pain behavior adversely affect the success of multidisciplinary rehabilitation of patients with chronic nonspecific low back pain (CNSLBP). Functional capacity evaluation (FCE) assessment should detect high levels of pain behavior to prevent the inclusion of unsuitable patients to functional rehabilitation programs. The aim of this study was to develop a Pain Behavior Assessment (PBA) and to evaluate its construct validity.

The PBA was developed by experts in the field and is literature-based. Inclusion criteria for participants of the validation study were: CNSLBP, age 20-60 years, referral for fitness-for-work evaluation. The PBA was applied by physiotherapists during FCE. Rasch analysis was performed to evaluate the construct validity of the PBA. Internal consistency was indicated by the person separation index (PSI), which corresponds to Cronbach's alpha.

145 male (72.5%) and 55 female patients were included. Rasch analysis removed 11 items due to misfit and redundancy, resulting in a final PBA of 41 items. Item mean fit residual was -0.33 (SD 1.06) and total item Chi square 100.39 (df = 82, p = 0.08). The PSI value was 0.83. DIF analysis for age and gender revealed no bias.

The PBA is a valid assessment tool to describe pain behavior in CNSLBP patients. The high PSI-value justifies the use of the PBA in individuals. The PBA may help to screen patients for high levels of pain behavior.