Measurement properties of Pain Catastrophizing Scale in individuals with chronic shoulder pain.

Background: Rotator cuff-related shoulder pain (RCRSP) is a common musculoskeletal disorder. Chronic symptoms, high-level pain intensity, and disability are associated with high levels of pain catastrophizing in this condition. Although the Pain Catastrophizing Scale (PCS) is widely used to assess pain catastrophizing in individuals with chronic symptoms, its measurement properties are still unknown for assessing individuals with chronic RCRSP.

Objective: To assess construct validity, reliability, and responsiveness of the PCS in individuals with chronic RCRSP.

Methods: Eighty-three adult individuals with chronic RCRSP were included in this study. The assessment of construct validity was based on hypothesis testing. Spearman's rank correlation coefficient was used to verify the correlation of the total score and rumination, magnification, and helplessness subscales of the PCS with pain intensity, disability, and fear of movement. Test-retest reliability was analyzed with Intraclass Correlation Coefficient (ICC)(3,1) and internal consistency was analyzed with Cronbach's alpha. Responsiveness was analyzed by effect sizes and the area under the receiver operating characteristic curve (AUC).

Results: The PCS showed significant moderate correlation (rho ≥ 0.40) with fear of movement (95% confidence interval [CI]: 0.23, 0.70), pain intensity (95% CI: 0.14, 0.64), and disability (95% CI: 0.17, 0.66), except the rumination and magnification subscales, which showed significant weak correlation with pain intensity (95% CI: 0.14, 0.58) and disability (95% CI: 0.12, 0.56), respectively. PCS presented good reliability (ICC > 0.7, 95% CI: 0.63, 0.88), and adequate internal consistency (Cronbach alfa > 0.7) and responsiveness based on effect sizes and AUC.

Conclusions: The PCS is a valid, reliable, and responsive instrument for assessing individuals with chronic RCRSP.