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Minimally important change, measurement error, and responsiveness for the Self-Reported Foot and Ankle Score
Maria C Cöster1, Anna Nilsdotter2, Lars Brudin3,4
1a Department of Orthopedics and Clinical Sciences , SUS Malmö , Malmö.
Abstract:
Background and purpose - Patient-reported outcome measures (PROMs) are increasingly used to evaluate results in orthopedic surgery. To enhance good responsiveness with a PROM, the minimally important change (MIC) should be established. MIC reflects the smallest measured change in score that is perceived as being relevant by the patients. We assessed MIC for the Self-reported Foot and Ankle Score (SEFAS) used in Swedish national registries. Patients and methods - Patients with forefoot disorders (n = 83) or hindfoot/ankle disorders (n = 80) completed the SEFAS before surgery and 6 months after surgery. At 6 months also, a patient global assessment (PGA) scale-as external criterion-was completed. Measurement error was expressed as the standard error of a single determination. MIC was calculated by (1) median change scores in improved patients on the PGA scale, and (2) the best cutoff point (BCP) and area under the curve (AUC) using analysis of receiver operating characteristic curves (ROCs). Results - The change in mean summary score was the same, 9 (SD 9), in patients with forefoot disorders and in patients with hindfoot/ankle disorders. MIC for SEFAS in the total sample was 5 score points (IQR: 2-8) and the measurement error was 2.4. BCP was 5 and AUC was 0.8 (95% CI: 0.7-0.9). Interpretation - As previously shown, SEFAS has good responsiveness. The score change in SEFAS 6 months after surgery should exceed 5 score points in both forefoot patients and hindfoot/ankle patients to be considered as being clinically relevant.
Insights
The minimally important change (MIC) for the Self-reported Foot and Ankle Score (SEFAS) is 5 points. This score indicates the smallest change patients perceive as relevant after orthopedic foot and ankle surgery.
Area of Science:
- Orthopedic Surgery
- Patient-Reported Outcome Measures (PROMs)
Background:
- PROMs are vital for evaluating orthopedic surgery outcomes.
- Establishing minimally important change (MIC) enhances PROM responsiveness.
- MIC quantifies the smallest score change patients deem relevant.
Purpose of the Study:
- To determine the MIC for the Self-reported Foot and Ankle Score (SEFAS).
- To assess SEFAS responsiveness in Swedish national registries.
- To validate SEFAS for forefoot and hindfoot/ankle disorders.
Main Methods:
- Patients (n=163) with foot/ankle disorders completed SEFAS pre- and 6-months post-surgery.
- A patient global assessment (PGA) scale served as the external criterion.
- MIC was calculated using median change scores and receiver operating characteristic (ROC) analysis (BCP, AUC).
Main Results:
- Mean SEFAS score change was 9 points for both forefoot and hindfoot/ankle disorders.
- The minimally important change (MIC) for SEFAS was determined to be 5 score points.
- Measurement error was 2.4, with a best cutoff point (BCP) of 5 and AUC of 0.8.
Conclusions:
- SEFAS demonstrates good responsiveness in orthopedic foot and ankle surgery.
- A SEFAS score change exceeding 5 points 6 months post-surgery is clinically relevant.
- This finding applies to both forefoot and hindfoot/ankle patient groups.
