Defining Erosive Disease in Rheumatoid Arthritis
Defining Erosive Disease in Rheumatoid Arthritis
Hello. I am Dr. Jonathan Kay, Professor of Medicine and Director of Clinical Research in the Division of Rheumatology at UMass Memorial Medical Center and the University of Massachusetts Medical School, both in Worcester, Massachusetts.
Today, I am going to talk about erosions in rheumatoid arthritis. The 2010 American College of Rheumatology (ACR)/European League Against Rheumatism (EULAR) criteria for the classification of rheumatoid arthritis purposely left out erosions as a criterion. This set of classification criteria was supposed to detect rheumatoid arthritis at an early stage when erosions were not necessarily expected to occur. Thus, erosions were not a criterion for defining rheumatoid arthritis.
However, the authors of these criteria indicated that evidence of erosions on plain radiographs would be prima facie evidence of rheumatoid arthritis. The criteria did not define specifically how erosions would be considered. To define erosions for the purpose of classifying rheumatoid arthritis, a task force of EULAR recently published their findings in the Annals of the Rheumatic Diseases.
This group looked at 2 cohorts of patients with early rheumatoid arthritis or early inflammatory arthritis, one from The Netherlands and the other from France. They looked at plain radiographs, which were scored by 1 of 2 readers for the number of joints with erosions. They looked at 28 joints and found that a cut-off of 3 or more joints with erosions had high specificity for the diagnosis of rheumatoid arthritis.
Why specificity? The group intended to apply this definition of erosion after a patient failed to meet the score-based algorithm cut-off of 6. They wanted a definition that would be very specific, but not necessarily sensitive. This application of the definition is somewhat in contradistinction to what the original group proposed when the classification criteria were designed.
Using plain radiographs to define erosions is less sensitive than other modalities, but also less expensive. Musculoskeletal ultrasonography and MRI can detect more erosions than plain radiographs, but are more difficult to obtain. Ultrasonography is operator-dependent and may be less readily available for clinical use.
The definition of erosions proposed by this EULAR task force will be interesting and should be applied to cohorts of patients with early inflammatory arthritis prospectively to determine its validity. As the Bard of Avon said (or as I paraphrase), "An erosion by any other name would be as deep."
Hello. I am Dr. Jonathan Kay, Professor of Medicine and Director of Clinical Research in the Division of Rheumatology at UMass Memorial Medical Center and the University of Massachusetts Medical School, both in Worcester, Massachusetts.
Today, I am going to talk about erosions in rheumatoid arthritis. The 2010 American College of Rheumatology (ACR)/European League Against Rheumatism (EULAR) criteria for the classification of rheumatoid arthritis purposely left out erosions as a criterion. This set of classification criteria was supposed to detect rheumatoid arthritis at an early stage when erosions were not necessarily expected to occur. Thus, erosions were not a criterion for defining rheumatoid arthritis.
However, the authors of these criteria indicated that evidence of erosions on plain radiographs would be prima facie evidence of rheumatoid arthritis. The criteria did not define specifically how erosions would be considered. To define erosions for the purpose of classifying rheumatoid arthritis, a task force of EULAR recently published their findings in the Annals of the Rheumatic Diseases.
This group looked at 2 cohorts of patients with early rheumatoid arthritis or early inflammatory arthritis, one from The Netherlands and the other from France. They looked at plain radiographs, which were scored by 1 of 2 readers for the number of joints with erosions. They looked at 28 joints and found that a cut-off of 3 or more joints with erosions had high specificity for the diagnosis of rheumatoid arthritis.
Why specificity? The group intended to apply this definition of erosion after a patient failed to meet the score-based algorithm cut-off of 6. They wanted a definition that would be very specific, but not necessarily sensitive. This application of the definition is somewhat in contradistinction to what the original group proposed when the classification criteria were designed.
Using plain radiographs to define erosions is less sensitive than other modalities, but also less expensive. Musculoskeletal ultrasonography and MRI can detect more erosions than plain radiographs, but are more difficult to obtain. Ultrasonography is operator-dependent and may be less readily available for clinical use.
The definition of erosions proposed by this EULAR task force will be interesting and should be applied to cohorts of patients with early inflammatory arthritis prospectively to determine its validity. As the Bard of Avon said (or as I paraphrase), "An erosion by any other name would be as deep."
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