A whole-joint, unidimensional, irreversible, and fine-grained MRI knee osteoarthritis severity score, based on cartilage, osteophytes and meniscus (OA-COM).

Eric C Sayre,Anona Thorne,Joel Singer,Hubert Wong,Ali Guermazi,John M Esdaile,Savvas Nicolaou,Jacek A Kopec,Jolanda Cibere,Sinan Kardeş

doi:10.1371/journal.pone.0258451

Eric C Sayre, Anona Thorne + Show 8 more

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https://doi.org/10.1371/journal.pone.0258451

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Abstract

ObjectiveTo develop a whole-joint, unidimensional, irreversible, and fine-grained MRI knee osteoarthritis (OA) severity score, based on cartilage, osteophytes and meniscus (OA-COM), and to predict progression across different severity states using OA-COM as outcome and clinical variables as predictors.MethodsPopulation-based knee pain cohort aged 40–79 was assessed at baseline and 7-year follow-up. OA-COM score was defined as the sum of MRI scores for cartilage, osteophytes and menisci, measured at 6, 8 and 6 sites, total score 0–54. To anchor severity levels, we fit cross-sectional logistic models using OA-COM to predict Kellgren-Lawrence (KL) grades in subsets at or one point below each grade. OA-COM threshold scores were selected on sensitivity, specificity, positive and negative predictive value. We developed longitudinal logistic models for OA-COM progression over each threshold over 7 years. Potential predictors included age, sex, BMI, malalignment, physical exam effusion, quadriceps weakness, and crepitus, selected on area under the receiver operating characteristic curve (AUC) and Akaike’s Information Criterion (AIC).ResultsOptimal OA-COM thresholds were 12, 18, 24 and 30, for KL grades 1 to 4. Significant predictors of progression (depending on threshold) included physical exam effusion, malalignment and female sex, with other selected predictors age, BMI and crepitus.ConclusionOA-COM (0–54 range) is a whole-joint, unidimensional, irreversible, and fine-grained MRI OA severity score reflecting cartilage, osteophytes and menisci. OA-COM scores 12, 18, 24 and 30 are equivalent to KL grades 1 to 4, while offering fine-grained differentiation of states between KL grades, and within pre-radiographic disease (KL = 0) or late-stage disease (KL = 4). In modeling, several clinical variables predicted progression across different states over 7 years.

Highlights

Osteoarthritis (OA) is a highly prevalent, disabling and costly condition
We have previously reported in this cohort that, based on Magnetic resonance imaging (MRI) cartilage damage and xray findings, 13% had no OA, 49% had pre-radiographic OA, and 38% had radiographic OA [10]
We have developed a whole-joint, unidimensional, irreversible, and fine-grained MRI knee OA severity score, the OA-COM score (0–54 range), which sums over multiple compartmentspecific scores involving cartilage, osteophytes and menisci

Summary

Introduction

Osteoarthritis (OA) is a highly prevalent, disabling and costly condition. In the U.S, clinical OA (defined on the basis of symptoms and physical examination findings) was seen in 27 million adults in 2008 [1]. Symptomatic radiographic knee OA affects 9.5% of elderly adults aged 63 years and older [2]. OA is more prevalent with older age and in obese people and OA constitutes an increasing public health burden. Kellgren-Lawrence (KL) grade is the de facto radiographic scale for structural osteoarthritis [4]. While for many decades the dominant scoring system for structural OA, the KL grading system has limitations. Chief amongst these is the coarse-grained property of the grading scale, accommodating 5 levels in total, with only 3 levels considered “osteoarthritis” (grades 2, 3 and 4). Magnetic resonance imaging (MRI) allows for much finer discrimination of structures (including soft tissue), and as such, theoretically can provide a finer-grained scale for “OA severity”

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