Psychometric properties and validation of the Polish version of the wheelchair user’s shoulder pain index

Moving in a manual wheelchair places significant strain on the upper extremities. The shoulder is particularly prone to overload owing to the joint's high mobility and a relatively small muscle mass, which is not suited to repeatedly support and move the body's weight. The purpose of our study was to evaluate the psychometric properties of the Wheelchair User's Shoulder Pain Index (WUSPI‑Pol) in wheelchair athletes. This study was a cross‑sectional survey. To assess psychometric properties, we have examined 74 individuals participating in team wheelchair sports who were experiencing shoulder pain. We have assessed the reliability, internal structure, test-retest repeatability, and validity of the Polish version of the WUSPI. Scale reliability for the study sample was very good. Cronbach's alpha for the total scale was 0.972. Test-retest reliability, assessed with the intraclass correlation coefficient (ICC), was very high (0.995), indicating near‑perfect agreement between the first and second administrations. Confirmatory factor analysis indicated a good model fit (CFI and TLI > 0.95; SRMR < 0.08), with RMSEA slightly higher than expected (0.076). External validity was evaluated by correlating WUSPI‑Pol scores with the QuickDASH and the Simple Shoulder Test; as expected, the correlations were positive. The Polish version (WUSPI‑Pol) is a reliable and valid instrument for assessing shoulder pain in wheelchair users.