Reliability and validity of the Wheelchair User's Shoulder Pain Index (WUSPI).

Many long term wheelchair users develop shoulder pain. The purpose of this study was to examine the reliability and validity of the Wheelchair User's Shoulder Pain Index (WUSPI), an instrument which measures shoulder pain associated with the functional activities of wheelchair users. This 15-item functional index was developed to access shoulder pain during transfers, self care, wheelchair mobility and general activities. To establish test-retest reliability, the index was administered twice in the same day to 16 long term wheelchair users and their scores for the two administrations were compared by intraclass correlation. To establish concurrent validity, the index was administered to 64 long term wheelchair users and index scores were compared to shoulder range of motion measurements. Results showed that intraclass correlation for test-retest reliability of the total index score was 0.99. There were statistically significant negative correlations of total index scores to range of motion measurements of shoulder abduction (r = -0.485), flexion (r = -0.479) and shoulder extension (r = -0.304), indicating that there is a significant relationship of total index score to loss of shoulder range of motion in this sample. The Wheelchair User's Shoulder Pain Index shows high levels of reliability and internal consistency, as well as concurrent validity with loss of shoulder range of motion. As a valid and reliable instrument, this tool may be useful to both clinicians and researchers in documenting baseline shoulder dysfunction and for periodic measurement in longitudinal studies of musculoskeletal complications in wheelchair users.