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

Abstract

Background:

Although clinically relevant thresholds such as minimal clinically important difference (MCID) and patient acceptable symptom state (PASS) have been widely described across orthopaedics, their application in hallux valgus surgery remains scarce. The purpose of this study was to determine the MCID and PASS thresholds for the visual analog scale (VAS) and Foot and Ankle Ability Measure (FAAM) scores after hallux valgus surgery.

Methods:

A retrospective review 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 preoperatively and 1 year postoperatively. The specific PROMs used were the FAAM–activities of daily living (FAAM-ADL), Single Assessment Numeric Evaluation (SANE), and VAS scale. Two methods were used to calculate MCID and PASS thresholds: a distribution-based approach for MCID and an anchor-based approach using responses to a 1-year postoperative satisfaction question for PASS. The analysis identified optimal cutoff points that maximized sensitivity and specificity based on the Youden index. Overall, 86% (136/158) completed baseline PROMs, and 73% (99/136) completed 1-year PROMs.

Results:

The distribution-based MCID for FAAM-ADL, SANE, and VAS were calculated to be 10.8, 14.1, and 1.2, respectively. The percentage of patients who achieved MCID thresholds was 54% for FAAM-ADL, 42% for SANE, and 96% for VAS. The PASS threshold for FAAM-ADL, SANE, and VAS were ≥78.5, ≥85, and ≤ 2, respectively. The percentage of patients who achieved PASS thresholds was 78% for FAAM-ADL, 72% for SANE, and 69% for VAS.

Conclusion:

This study identified useful values for the MCID and PASS thresholds of FAAM-ADL, SANE, and VAS scores at 1-year follow-up for patients undergoing hallux valgus surgery. Overall, despite not meeting the MCID thresholds, patients undergoing hallux valgus surgery were still likely to be satisfied with their surgery.