Correlating the Patient Reported Outcomes Measurement Information System (PROMIS) to the Foot and Ankle Outcome Score and Patient Functional Testing in Total Ankle Arthroplasty Patients
Authors: Mizher Rami , Rajan Lavan , Kim Jaeyoung , Cychosz Chris , Demetracopoulos Constantine , Ellis Scott J. 
Published: February 2023

Category: Ankle Arthritis; Other Introduction/ Purpose: The orthopaedic field, including foot and ankle surgery, continues to rely on patient reported outcome measures (PROMs) as the cornerstone of research studies. Various questionnaires exist, each with their advantages and disadvantages. The Patient-Reported Outcomes Measurement Information System (PROMIS) has become increasingly popular due to its reliability, validity, and efficiency. This system has been tested against the Foot and Ankle Outcome Score (FAOS) for foot and ankle conditions, however little is known about its validity for patients with ankle arthritis undergoing total ankle arthroplasty (TAA). Additionally, its relationship to functional tests is unknown, which could reveal whether it could be used in lieu of these resource-intensive assessments. Therefore, we aimed to validate PROMIS against the FAOS and functional tests in TAA patients. Methods: This prospective cohort study included 102 patients (mean age: 63.5 years) who were diagnosed with ankle arthritis and underwent subsequent TAA. Preoperative PROMIS scores, FAOS, and functional tests including the 4 square test (4SST), timed up and go (TUG), and sit-to-stand (STS) were gathered and analyzed preoperatively. PROMIS physical function and pain interference domains were tested for reliability using Rasch partial credit models. Convergent validity between PROMIS physical function and pain interference, and FAOS function, daily living was evaluated using Spearman’s correlation coefficient. In addition, the relationship between the functional tests and all 6 PROMIS domains were evaluated using Spearman’s correlation coefficient. Results: Infit and outfit mean squares (MSQs) for PROMIS physical function ranged from 0.61 – 0.78, indicating a good fit in the Rasch model. Similarly, infit and outfit MSQs for PROMIS pain interference ranged from 0.77 – 0.8, also indicating a good fit. Separation reliability was 0.89 for physical function and 0.85 for pain interference, indicating good reliability to actual patient function and pain levels. PROMIS physical function demonstrated a moderate positive correlation with FAOS function, daily living (r=0.52) while pain interference demonstrated a moderate negative correlation (r=-0.52). PROMIS physical function demonstrated statistically significant weak negative correlations for all 3 functional tests (r=-0.19 for 4SST, r=-0.27 for TUG, r=-0.2 for STS) [Figure 1]. Conclusion: Our study revealed good reliability of PROMIS physical function and pain interference domains, with a moderate correlation to FAOS function, daily living. Additionally, we found weak correlations between PROMIS physical function and functional tests and no significant correlations between pain interference and functional tests. This indicates acceptable convergent validity to the FAOS but not to functional tests. Therefore, while PROMIS provides reliable and valid measures, it does not replace the need for functional tests, which should be pursued in conjunction to deliver a complete assessment of TAA patients.