A Clinical Prediction Rule for Predicting the Health-related Quality of Life after 5 Months in Patients with Knee Osteoarthritis Undergoing Conservative Treatment.

Objective: This study aimed to derive a clinical prediction rule (CPR) that can predict changes in health-related quality of life at 5 months for patients with knee osteoarthritis (KOA) undergoing conservative treatment.

Methods: Patients with KOA receiving physical therapy and exercise therapy at an outpatient clinic were included in this study. The basic characteristics, medical information, and motor function test results were recorded at baseline. The primary outcome measure was the change in the Japan Knee Osteoarthritis Measure (JKOM) 5 months after the baseline measurement. A decision tree analysis was performed with the basic characteristics, medical information, and the motor function test results as the independent variables and the changes in the JKOM after 5 months (≥8 in the improved groups) as the dependent variable.

Results: Analyzed data from 87 patients. The variables included the visual analog scale score, bilateral KOA, 5-m walk test, JKOM, and body mass index. Six CPRs were obtained from the terminal nodes. Accuracy validation of the model for the entire decision tree revealed an area under the receiver operating characteristic curve of 0.87 (validation data: 0.83), a positive likelihood ratio of 2.6, and a negative likelihood ratio of 0.1.

Conclusion: This CPR is an inspection characteristic that can exclude the possibility of the occurrence of an event based on a negative result. However, since the results of this study represent the first process of utilizing the CPR in actual clinical practice, its application should be kept in mind.