Knee symptoms among adults at risk for accelerated knee osteoarthritis: data from the Osteoarthritis Initiative.

The purpose of this study was to examine if adults who develop accelerated knee osteoarthritis (KOA) have greater knee symptoms with certain activities than those with or without incident common KOA. We conducted a case-control study using data from baseline and the first four annual visits of the Osteoarthritis Initiative. Participants had no radiographic KOA at baseline (Kellgren-Lawrence (KL) <2). We classified 3 groups as follows: (1) accelerated KOA: > = 1 knee developed advance-stage KOA (KL = 3 or 4) within 48 months, (2) common KOA: > = 1 knee increased in radiographic severity (excluding those with accelerated KOA), and (3) no KOA: no change in radiographic severity by 48 months. We focused on individual items from the WOMAC pain/function subscales and KOOS pain/symptoms subscales. The index visit was a year before a person met the definition for accelerated, common, or no KOA. To examine group difference in knee symptoms, we used ordinal logistic regression models for each symptom. Results are reported as odds ratios (OR) and 95% confidence intervals (CI). Individuals who developed accelerated KOA were more likely to report greater difficulty with lying down (OR = 2.10, 95% CI = 1.04 to 4.25), pain with straightening the knee fully (OR = 2.04, 95% CI = 1.08, 3.85), and pain walking (OR = 2.49, 95% CI = 1.38, 4.84) than adults who developed common KOA. Individuals who develop accelerated KOA report greater symptoms with certain activities than those with common KOA. Our results may help identify individuals at risk for accelerated KOA or with early-stage accelerated KOA.