Minimal clinically important difference (MCID) for patient-reported shoulder outcomes

Background: The minimal clinically important difference (MCID) is used when interpreting the importance of outcome data. However, a consensus regarding the MCID for commonly used patient-reported outcomes in shoulder surgery has not been established. The purpose of this systematic review was to evaluate the available literature on shoulder MCID to improve clinical interpretation of shoulder outcome data.

Methods: A systematic review of the literature was conducted to identify studies reporting anchor-based MCID values for the patient-reported outcomes recommended by the American Shoulder and Elbow Surgeons (ASES): Veterans Rand 12 score, ASES score, Single Assessment Numeric Evaluation (SANE) score, Western Ontario Rotator Cuff (WORC) score, Western Ontario Osteoarthritis Score (WOOS), Western Ontario Shoulder Instability Index (WOSI), Pennsylvania Shoulder Score, and Oxford Shoulder Score (OSS).

Results: A total of 14 articles reporting anchor-based MCID values were included in the final analysis. No studies reporting the Western Ontario Osteoarthritis Score (WOOS) were identified. The ASES score (6 studies), OSS (4 studies), and WORC score (2 studies) were the only instruments investigated in more than 1 study. The average reported MCID values for the ASES, OSS, and WORC scores were 15.5 (15% total difference), 275.7 (13% total difference), and 6 (13% total difference), respectively. The vast majority of studies failed to report information necessary to validate the credibility of these MCID values.

Discussion and conclusion: The current utility of the MCID for patient-report shoulder outcome instruments is limited by poor study methodology, inadequate reporting, and a lack of data. Further research is needed to more clearly define the MCID values for commonly used patient-reported outcomes in shoulder surgery.