Development and Evaluation of an Activity Rating Scale for Disorders of the Knee

TLDR

Knee disorder studies need to report activity levels to enable comparison of treatment groups and generalize findings. The study aimed to develop and evaluate a new activity rating scale for knee disorder patients. The scale was tested for reliability in 40 subjects over two visits a week apart and for validity by comparing scores with established activity scales and with age. Patients completed the scale in about a minute, found it easy to use, and the instrument showed excellent reliability (ICC 0.97) and strong correlations with existing scales, while also inversely correlating with age, supporting its validity and usefulness for comparative research.

Abstract

Reports of clinical studies of patients with knee disorders should routinely include their activity levels to enable comparison of treatment groups and to allow generalizability. The goal of this study was to develop and evaluate a new rating scale to measure activity levels of patients. We assessed reliability by administering the scale to 40 subjects on 2 separate occasions, 1 week apart. Validity was evaluated by comparing the activity rating on the new scale with that from other instruments that use activity level scales (concurrent construct validity) and also by correlating the score on the new scale with age (divergent validity). Patients easily understood the scale and were able to complete it in 1 minute. The reliability was high (intraclass correlation coefficient, 0.97). The scale also correlated well with existing activity rating scales: Spearman correlation coefficient for Cincinnati score, 0.67; for Tegner scale, 0.66; for Daniel scale, 0.52. The activity score was significantly inversely correlated with age (P=0.002), indicating divergent validity. This instrument will facilitate generalizability of results and allow more accurate comparisons among patient groups in outcomes research in sports medicine.