Agreement between the American Shoulder and Elbow Surgeons Society Standardized Shoulder Assessment score (ASES) and the Oxford Shoulder Score (OSS) in patients presenting with shoulder pathology: A cohort analysis of the Clinical Quality Registry for Outcomes in Shoulder and Elbow Pathology (CROSEP) registry.

Background: The choice of patient-reported outcome measure (PROM) used in shoulder studies varies based on clinician's preference and location. This creates difficulties when attempting to compare studies which have used different PROMs as their outcome measure. This study aims to assess the agreement between the American Shoulder and Elbow Surgeons score (ASES) and the Oxford Shoulder Score (OSS), and identify factors associated with agreement.

Methods: Patients with shoulder pathology were identified from a multi-cohort observational practice registry. 1050 paired ASES and OSS pre-treatment scores were prospectively collected. Linear regression was performed to assess the agreement between the PROMs. Mixed-effects analysis of variance was performed to assess the influence of factors associated with agreement.

Results: Regression for mean total and mean function ASES and OSS demonstrated good fit (adjusted R 57.7%, P < 0.001; and 63.9%, P < 0.001). Mean pain subscore demonstrated a poorer fit (adjusted R 39.4%, P < 0.001). Crosswalks to convert between mean scores were produced with reasonable precision. Veterans RAND 12-Item Health Survey score, age and diagnosis cohort influenced agreement.

Conclusion: Mean total and mean function ASES and OSS scores agree well with each other. This allows for a more informed comparison of studies using either PROMs as their outcome measure.