Defining Region and Duration-Specific Substantial Clinical Benefit Values for the Simplified Chinese Lower Extremity Functional Scale

Abstract

Background A single substantial clinical benefit (SCB) value for the Simplified Chinese Lower Extremity Functional Scale (SC-LEFS) that can be applied to those with lower extremity musculoskeletal injuries is available. However, unique SCB values defined by specific body region and symptom duration may enhance the precision of the SC-LEFS in clinical assessments. Methods This study aim to determine unique SCB values for the SC-LEFS based on symptom duration and body region. Patients 18–50 years of age referred to physical therapy with a non-arthritic musculoskeletal injury to the knee or ankle/foot completed the SC-LEFS at initial assessment and 4-weeks follow-up. Demographic information, including duration of symptoms was also obtained. Patients were classified into “improved” and “not improved” groups based on self-report after 4-weeks of physical therapy. SCB values were determined to best distinguish between the two groups. Receiver operator characteristic (ROC) curve analysis defined the sensitivity and specificity for these SCB values. Results Three hundred and thirteen patients with a mean age of 33.7 (SD 9.3) years were included in the knee region analysis and 354 patients with a mean age of 32.9 (SD 9.4) years in the ankle/foot region analysis. For those with knee injuries, SCB values of 9.5 and 5.5 were found for patients with symptom duration ≤ 3 months and symptom duration > 3 months, respectively. For those with ankle/foot injuries, SCB values 12.5 and 8.5 were found for patients with symptom duration ≤ 3 months and symptom duration > 3 months, respectively. The sensitivity and specificity for these SCB values ranged from 0.67 to 0.72 and from 0.66 to 0.68, respectively, with area under the cures (AUC) being between 0.67 to 0.72. All 95% confidence intervals for AUC were greater than 0.50, indicating adequate accuracy. Conclusion This study determined specific SCB values for the SC-LEFS after four weeks of physical therapy based on region of injury and symptom duration. These unique values may better allow clinicians to distinguish those “improved” from “not improved” in Chinese-speaking patients with non-arthritic musculoskeletal knee, ankle, or foot injuries. Trial registration: This project was registered with the Chinese Clinical Trial Registry (ChiCTR2100052104) on 2021-10-17.