Establishment of Minimum Clinically Important Difference and Patient Acceptable Symptom State Thresholds in Foot and Ankle Ability Measure and Visual Analogue Scale Scores After Hallux Valgus Surgery

Category: Bunion Introduction/Purpose: The purpose of this study was to determine the minimal clinically important difference (MCID) and the patient acceptable symptom state (PASS) threshold for the Visual Analogue Scale (VAS) and Foot and Ankle Ability Measure (FAAM) Scores after Hallux Valgus surgery. Methods: A retrospective review of prospective collected data was performed in patients undergoing hallux valgus surgery at a single institution from January 2021 through December 2022. Patient-reported outcome measures (PROMs) were collected pre-operatively and 1 year post-operatively. The specific PROMs utilized were the FAAM- Activities of Daily Living (FAAM-ADL), Single Assessment Numeric Evaluation (SANE), and VAS scale. The study measured change in PROMs from before surgery to one year after surgery to determine delta. Two methods were used to calculate MCID and PASS thresholds: A distribution-based approach and an anchor-based approach using responses to a one-year postoperative satisfaction question. The analysis identified optimal cut-off points that maximized sensitivity and specificity based on the Youden index. The percentage of patients reaching these optimal MCID and PASS thresholds was also determined. Results: Overall, 86% (136/158) completed baseline PROMs, and 72.7% (99/136) completed 1-year PROMs. The distribution-based MCID for FAAM-ADL, FAAM-ADL-SANE, , and VAS were calculated to be 10.8, 14.1, and 1.2 respectively. The rate of patients who achieved MCID thresholds was 54% for FAAM-ADL, 42% for FAAM-ADL-SANE, and 95.8% for VAS. The PASS threshold for FAAM-ADL, FAAM-ADL-SANE, and VAS were ≥78.5, ≥85, and ≤ 2, respectively. The rate of patients who achieved PASS thresholds was 77.5% for FAAM-ADL, 71.4% for FAAM-ADL-SANE, and 68.7% for VAS. Conclusion: This study identified useful values for the MCID and PASS thresholds at 1-year follow-up for patient undergoing hallux valgus surgery of FAAM-ADL, FAAM-ADL-SANE, and VAS scores.