Purpose

The purpose of this study was to evaluate the psychometric properties of the PROMIS-Physical Function (PF) and Worst Stiffness Numeric Rating Scale (NRS) among patients with tenosynovial giant cell tumors (TGCT).

Methods

Measurement properties of the customized lower extremity (LE) and upper extremity (UE) PROMIS-PF scales and Worst Stiffness NRS were assessed using data from the Phase 3 ENLIVEN trial (n = 120). Anchor- and distribution-based analyses were utilized to derive a responder threshold for meaningful change over time. The Patient Global Rating of Concept (PGRC)-Physical Functioning and Patient Global Impression of Change (PGIC)-Stiffness served as anchors. Responsiveness and responder threshold analyses were from baseline to week 25.

Results

Cronbach's alpha values for internal consistency reliability were 0.93 and 0.91 for the PROMIS-PF LE and UE, respectively. Test-retest reliability intra-class correlation coefficients were > 0.75 for both instruments. Convergent validity for both instruments was supported by moderate to strong correlations (≥0.30) with the Brief Pain Inventory and EQ-5D. Known-groups validity was established between subgroups stratified by pain level (p < 0.05). Responsiveness was supported by evaluating change scores among different levels of change in PGRC-Physical Functioning and PGIC-Stiffness (overall F values < 0.001). Triangulation of responder definition analyses resulted in a threshold of ≥3 for the PROMIS-PF and ≥ 1 for the Worst Stiffness NRS.

Conclusion

This study is the first to establish the psychometric properties of patient-reported outcome measures in TGCT. The evidence demonstrates that the PROMIS-PF and Worst Stiffness NRS have good reliability, validity, and responsiveness, and provides guidance for the interpretation of meaningful change.