Knee Osteoarthritis Worsening Across the Disease Spectrum and Future Knee Pain, Symptoms, and Functioning: A Multisite Prospective Cohort Study

Objective Prognostic estimates for knee osteoarthritis worsening over the full disease spectrum have not been reported. Osteoarthritis Initiative data were used to determine the association between knee radiographic osteoarthritis worsening and future knee pain and function. Methods Yearly data over a 5-year period were analyzed. Outcome measures were the Western Ontario and McMaster Universities Osteoarthritis Index and the Knee Injury and Osteoarthritis Outcome Score pain and symptoms scales. Knees were grouped based on whether yearly Kellgren/Lawrence (K/L) grades worsened. Associations of yearly K/L worsening with knee pain, symptoms, or function scores at the end of the year and with lagged outcomes observed at least 1 year after worsening were assessed using linear models with generalized estimating equations. Results A total of 25,932 knee-years of observations were examined in the primary analysis. For knees with yearly K/L worsening, all outcome scores were significantly worse (P values from 0.02 to