Comparing the Responsiveness of the Global Rating Scale With Legacy Knee Outcome Scores: A Delaware-Oslo Cohort Study

Abstract

Background: The selection of patient-reported outcome measures (PROMs) is essential for obtaining meaningful information to treat a patient, determine a plan of care, and make clinical decisions; however, the process of selecting PROMs for clinical care is difficult, with the need to balance these multiple factors. Variation makes it difficult to compare data across providers and studies. Hypothesis/Purpose: The purpose was to determine the responsiveness of 4 PROMs via effect size and the presence of a ceiling effect in the 5 years after anterior cruciate ligament reconstruction (ACLR). We hypothesized that the single-item Global Rating Scale (GRS) would have an effect size and ceiling effect similar to the commonly used legacy PROMs. Study Design: Cohort study (diagnosis); Level of evidence, 2. Methods: Of the 300 participants, 218 had ACLR, completed postoperative progressive criterion-based rehabilitation early after surgery, and were followed for 5 years. We collected data based on the GRS, the Knee Outcome Survey–Activities of Daily Living Scale (KOS-ADLS), the International Knee Documentation Committee–Subjective Knee Form (IKDC-SKF), and the KOOS (Knee injury and Osteoarthritis Outcome Score) before and after training and at 6, 12, 24, and 60 months after ACLR. Results: The IKDC-SKF had the largest effect sizes and lowest ceiling effects. The GRS had a similar size and change in both effect size and ceiling effect when compared with the longer PROMs. The GRS and IKDC-SKF had a correlation of 0.72, and the GRS had a minimal detectable change of 2.9 or 4.8, depending on methodology. Conclusion: The GRS responded similarly to the IKDC-SKF, KOS-ADLS, and KOOS and was responsive to patient change. The ease of use and patient-specific nature of the question means that it may be appropriate to use the GRS in clinical care as a consistent measure throughout the course of rehabilitation.