Responsiveness and minimal important change of the Oxford Shoulder Score, EQ-5D, and the Fear-Avoidance Belief Questionnaire Physical Activity subscale in patients undergoing arthroscopic subacromial decompression

Introduction
Adequate responsiveness and knowledge of the minimal important change (MIC) is essential when using patient-reported outcome measures to assess treatment efficacy.

Objective
The objective of this study was to evaluate the responsiveness and MIC of common outcomes in patients with subacromial impingement syndrome undergoing arthroscopic subacromial decompression.

Methods
At baseline and 6 months after surgery, patients completed the Oxford Shoulder Score (OSS), EQ-5D 5-level utility index, EQ visual analogue scale, Fear-Avoidance Belief Questionnaire Physical Activity subscale (FABQ-PA), assessed pain (pain visual analogue scale), and Subjective Shoulder Value. Furthermore, at the 6-month follow-up, patients assessed the overall change with a Global Rating of Change Scale. Responsiveness was examined by analyzing the area under the receiver operating characteristics curve and correlations between the change scores. MIC was assessed using the optimal cutoff point at the receiver operating characteristics curve.

Results
Area under the receiver operating characteristics curve estimates were 0.96 (95% confidence interval [CI] 0.91,1.00) for OSS, 0.82 (95% CI 0.66,0.99) for EQ-5D 5-level utility index, 0.73 (95% CI 0.58,0.87) for EQ visual analogue scale, and 0.74 (95% CI 0.58,0.90) for FABQ-PA. MIC were 6.0 points for OSS, 0.024 points for EQ-5D 5-level utility index, 10.0 points for EQ visual analogue scale, and -5.0 points for FABQ-PA.

Conclusion
Responsiveness of the OSS, EQ-5D, and FABQ-PA was sufficient to measure improvement after arthroscopic decompression surgery.