CONCURRENT VALIDITY OF PATIENT RATING SCALES IN ASSESSMENT OF OUTCOME AFTER ROTATOR CUFF REPAIR

The purpose of this study was to compare the concurrent validity of four questionnaires in the assessment of outcome after rotator cuff repair. Sixty-two patients, who were at least two years post-rotator-cuff repair, completed three upper extremity scales: the Western Ontario Rotator Cuff (WORC) index, the Disabilities of the Arm, Shoulder and Hand (DASH) and the Simple Shoulder Test (SST), and a measure of general health status (SF-36). Internal and external rotation ranges of motion and isometric strength were measured. Pearson correlations were used to evaluate the construct whereby scores should be related to the severity of measured impairments. One-way ANOVA was used to determine the ability of the questionnaires to discriminate between groups expected to have different outcomes based on measured impairment or worker's compensation status. The upper extremity questionnaires demonstrated similar response distributions and were highly correlated (0.88 < r < 0.91). The response distribution of the SF-36 was different from the other scales and its correlation with them was moderate (0.58 < r < 0.75). The upper extremity measures demonstrated better correlations with measured impairments (0.18 < r < 0.56) than the SF-36 (0 < r < 0.40). All the questionnaires were able to discriminate between levels of impairment and worker's compensation status. This study supported the validity of upper extremity scales to measure cuff-related disability and suggests that the use of both specific and general health measures provides a more comprehensive evaluation of patient outcome.