Validation of the Super Simple Hip score combined with the University of California, Los Angeles activity scale for younger patients

Introduction: Patient-reported outcome measures (PROMs) are used increasingly, but for young patients with hip complaints, traditional scoring systems have a ceiling effect that limits their usability. We developed and validated the Super Simple Hip (SUSHI) score, a PROM specifically targeted at younger patients with hip complaints. Although the SUSHI measured hip problems adequately, the responsiveness of its activity rating component was considered inadequate. Consequently, we replaced the activity rating component by the University of California, Los Angeles (UCLA) activity scale. The aim of this study was to validate the resulting new 10-item SUSHI-UCLA score. Methods: A prospective multicentre observational cohort study was performed. Patients between 18 and 59 years, who visited the Orthopaedic Department with hip complaints, completed the SUSHI-UCLA and hip osteoarthritis outcome score (HOOS) twice before their 1st appointment, and once 16 months after. Results: 142 patients were included (mean age 49 years; SD 8.8). The SUSHI-UCLA score correlated well with the HOOS, both before and after treatment (Spearman’s rho = 0.739 and 0.847, respectively, both p < 0.001). The responsiveness of both the SUSHI-UCLA score and the UCLA activity scale was high (standardised response mean = 2.51 and 1.35 respectively). The reproducibility was good (interclass correlation coefficient for agreement = 0.962). The minimal important change was 21.2. No significant floor or ceiling effect was observed. Conclusion: The SUSHI-UCLA score is an adequate PROM to measure hip complaints in younger patients and includes a validated activity rating.