Comparing improvement ratings and minimal clinically important difference values between patients and physical therapists

Background The minimal clinically important difference (MCID) is most commonly defined using patient-reported assessments of meaningful change. However, MCID values may also be derived from clinician judgments. Patient and physical therapist (PT) ratings of meaningful change may differ due to differences in clinical priorities and observational focus. It remains unclear whether MCID values defined by PTs align with those defined by patients themselves. Methods This study aim to determine the agreement in perceived improvement between patients and PTs and compare MCID values for the Simplified Chinese Lower Extremity Functional Scale (SC-LEFS) based on these improvement ratings. Patients aged 18–50 years with non-osteoarthritic lower extremity injuries completed the SC-LEFS at initial assessment and 4-weeks follow-up. After 4-weeks of physical therapy, patients were classified into “improved” and “not improved” groups by using a 7-point global rating of change (GROC) scale. Based on both the patient’s and physical therapist’s independent ratings, patients were separately categorized as “improved” (those reporting being improved or much improved) or “not improved” (those reporting slightly improved, no change, slightly worse, worse, or greatly worse). Separate SC-LEFS MCID values were determined that best distinguished between the two groups for the patient and PT rating. Receiver operator characteristic (ROC) curve analyses were done to define the sensitivity and specificity for these MCID values. Results A total of 763 patients with lower extremity injuries were included. Agreement between patients’ and PTs’ rating was substantial (quadratic weighted kappa = 0.8: 95% CI [0.77–0.84]). MCID values of 9.5 were found for both patient report and PT rating, with sensitivity and specificity ranging between of 0.66 and 0.72. The area under the cures (AUC) were 0.74 (95% CI [0.71–0.78]) for both patient report and PT rating. Conclusion After 4 weeks of physical therapy, patients and PTs demonstrated agreement in their improvement ratings, and the SC-LEFS MCID thresholds for defining improvement were same for both groups.