Background: The Western Ontario Rotator Cuff Index (WORC) is a joint specific outcome tool that assesses the quality of life in patients with various rotator cuff problems. Our purpose was to evaluate selected psychometric characteristics (internal consistency, validity, reliability and agreement) of the Polish version of WORC in patients undergoing rotator cuff repair.
Methods: Sixty-nine subjects took part in the study with a mean age 55.5 (range 40-65). All had undergone arthroscopic rotator cuff repair in 2015-2016. Data from 57 patients in whom symptoms in the shoulder joint had not changed within 10-14 days were analyzed in a WORC test-retest using the Intraclass Correlation Coefficient (ICC), Standard Error of Measurement (SEM) and Minimal Detectable Change (MDC). WORC was compared to the short version of the Disabilities of Arm, Shoulder and Hand Questionnaire (QuickDash) and the Short Form-36 v. 2.0 (SF-36).
Results: High internal consistency of 0.94 was found using Cronbach's alpha coefficient. Reliability of the WORC resulted in ICC = 0.99, agreement assessed with SEM and MDC amounted to 1.62 and 4.48 respectively. The validity analysis of WORC showed strong correlations with QuickDash and SF-36 PCS (Physical Component Summary), while moderate with SF-36 MCS (Mental Component Summary). WORC had no floor or ceiling effect.
Conclusions: The Polish version of the WORC is a reliable and valid tool with high internal consistency for assessing the quality of life in patients undergoing arthroscopic rotator cuff repair.
Keywords: Quality of life questionnaires; Reliability; Rotator cuff tear; Validity; WORC.