Validity Assessment of the Swiss Orthopaedics Minimal Data Set compared to the subjective shoulder value for rotator cuff repair in relation to Constant score

Abstract

Background: Despite numerous Patient Reported Outcome Measures (PROMs) in shoulder surgery, no standard has been established for subjective measurement of shoulder outcomes. Purpose: This study examines the validity of the Swiss Orthopaedics Minimal Data Set (SOMDS) compared to the subjective shoulder value (SSV) for shoulder pathology in relation to Constant score in patients undergoing arthroscopic rotator cuff reconstruction. Methods: As part of the ARCR_Pred Cohort Study, 973 patients undergoing arthroscopic rotator cuff reconstruction were included from June 2020 to November 2021 across 19 centers. Follow-up examinations at 12 months postoperatively assessed the Constant score, the SOMDS, the subjective shoulder value (SSV), and the EQ-5D-5L index. The validity of both the SOMDS and the SSV was evaluated in comparison to the Constant score, using Cronbach’s alpha for consistency and correlation analyses for validity. Results were visualized with boxplots to assess ceiling effect. Results: The SOMDS has a Cronbach’s alpha of α = 0.56. Excluding the level of education sub-item improves internal consistency to α = 0.64. A linear regression model shows a strong correlation between the SOMDS and Constant score (r = 0.657, p < 0.001), superior to the EQ-5D-5L index (r = 0.657 vs. 0.562, p = 0.002) and comparable to the SSV (r = 0.657 vs. 0.644, p = 0.644). Sub-item correlations were also highly significant (p < 0.001). Boxplot analysis reveals a more pronounced ceiling effect for the SOMDS compared to the Constant score and the SSV, particularly affecting the joint-specific satisfaction sub-item. Conclusion: The SOMDS is a time-saving alternative to the Constant score, with a comparable validity to but higher ceiling effect than the SSV. SOMDS and SSV are useful depending on the parameters required to be recorded in everyday clinical practice or for study needs: SSV for patient-perceived functionality and SOMDS for broader assessment of health dimensions. The SOMDS without the level of education sub-item has improved internal consistency. What this study adds: The SOMDS is a valid tool for shoulder outcome assessment. How this study might affect research, practice or policy: Standardizing shoulder outcome measures using the SSV for patient-perceived functionality and the SOMDS for a broader evaluation of health dimensions.