Risk factors can classify individuals who develop accelerated knee osteoarthritis: Data from the osteoarthritis initiative

Abstract

We assessed which combinations of risk factors can classify adults who develop accelerated knee osteoarthritis (KOA) or not and which factors are most important. 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 three groups (matched on sex): (i) accelerated KOA: >1 knee developed advance-stage KOA (KL = 3 or 4) within 48 months; (ii) typical KOA: >1 knee increased in radiographic scoring (excluding those with accelerated KOA); and (iii) No KOA: no change in KL grade by 48 months. We selected eight predictors: Serum concentrations for C-reactive protein, glycated serum protein (GSP), and glucose; age; sex; body mass index; coronal tibial slope, and femorotibial alignment. We performed a classification and regression tree (CART) analysis to determine rules for classifying individuals as accelerated KOA or not (no KOA and typical KOA). The most important baseline variables for classifying individuals with incident accelerated KOA (in order of importance) were age, glucose concentrations, BMI, and static alignment. Individuals <63.5 years were likely not to develop accelerated KOA, except when overweight. Individuals >63.5 years were more likely to develop accelerated KOA except when their glucose levels were >81.98 mg/dl and they did not have varus malalignment. The unexplained variance of the CART = 69%. These analyses highlight the complex interactions among four risk factors that may classify individuals who will develop accelerated KOA but more research is needed to uncover novel risk factors. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:876-880, 2018.

Role of Magnetic Resonance Imaging in Classifying Individuals Who Will Develop Accelerated Radiographic Knee Osteoarthritis

“…Fifty‐four cases (AKOA) and 108 participants in the control group (54 adults with typical radiographic KOA and 54 adults with no radiographic KOA) met the inclusion criteria at baseline. This cohort has been described previously . In brief, the sample was predominantly female (63%), with mean age 59 years (SD = 8), and body mass index 28 kg/m 2 (SD = 5; Table ).…”

“…We selected this definition instead of five other radiographic criteria for AKOA based on a previous analysis that determined this was an optimal definition of AKOA . This definition is consistent with our original attempt to classify adults at risk for AKOA . Eligible participants had Kellgren–Lawrence (KL) grade <2 at baseline in both knees.…”

“…We performed classification and regression tree (CART) analyses to determine classification rules and important variables for: Model 1: a model with MR features only; Model 2: a previously published base model with clinically accessible variables (i.e., serological, radiographic, and demographic) that now also includes self‐reported symptoms, clinical exam findings, and physical function; and Model 3: a combined model comprised of the clinically accessible variables and MR features.…”

“…3 This definition is consistent with our original attempt to classify adults at risk for AKOA. 5 Eligible participants had Kellgren-Lawrence (KL) grade <2 at baseline in both knees. Cases were participants with AKOA, defined as the development of advanced-stage radiographic KOA (KL grade 3 or 4) by the 48-month visit.…”

“…Since the rate of disease onset offers only a short opportunity to intervene it would be helpful to classify people at‐risk for AKOA to create an opportunity to develop and deliver prevention strategies. We previously classified individuals using serum, radiographic, and demographic/anthropometric (age and body mass index [BMI]) participant characteristics and explained 31% of the variability with high specificity but low sensitivity . These results suggest that further analyses are needed with additional baseline characteristics to better discriminate between individuals that will and will not develop AKOA.…”