Development and psychometric evaluation of a Rasch-based brief form of the work rehabilitation questionnaire for low back pain.

BACKGROUND

Low back pain (LBP) is a leading cause of work-related disability. Comprehensive instruments such as the Work Rehabilitation Questionnaire (WORQ) capture multiple domains of functioning but are lengthy and impractical for routine use.

OBJECTIVE

To develop and evaluate a LBP-specific brief form of the WORQ.

DESIGN, SETTING, AND POPULATION: A secondary psychometric analysis of clinical cohort data using the LBP-validated version of the WORQ using Rasch analysis. Data analysis was conducted at the Spine Center of Southern Denmark. The cohort comprised 425 adults with LBP, aged 18-65, employed or seeking work.

INTERVENTION: not applicable.

MAIN OUTCOME MEASURES: Work-related disability was measured using the LBP-validated WORQ (psychological, physical, and cognitive subscales), the Oswestry Disability Index, a numerical pain rating scale, and a single-item Work Ability Index. Rasch analysis was applied at the subscale level to guide item reduction and evaluate model fit, item performance, unidimensionality, category functioning, and differential item functioning.

RESULTS

The brief WORQ-LBP comprised 15 items: 6 cognitive, 4 physical, 3 psychological, and 2 additional items (fatigue and sleep disturbances). Rasch analysis confirmed good model fit for the physical and psychological subscales and acceptable fit for the cognitive subscale. All subscales demonstrated acceptable internal consistency (Cronbach's α ≥0.79) and reliability. Measurement precision was highest for individuals with moderate impairments, and minor disordered thresholds occurred mainly in lower response categories. No substantial item dependence or differential item functioning was detected. Transformed scores enable interval-level interpretation, supporting use in clinical and research contexts.

CONCLUSION

The brief WORQ-LBP is a psychometrically robust, multidimensional instrument for assessing work-related disability in individuals with LBP. Because responsiveness and predictive validity were not evaluated, further longitudinal studies are needed to confirm evaluative applications.