Kunihiro Nishimura, MD, MPH, PhD; Akio Morinobu, MD, PhD; Shunichi Kumagai, MD, PhD
Potential Financial Conflicts of Interest: None disclosed.
Nishimura K, Morinobu A, Kumagai S. Biological Significance of Anti–Cyclic Citrullinated Peptide Antibody in Rheumatoid Arthritis. Ann Intern Med. 2008;148:403-404. doi: 10.7326/0003-4819-148-5-200803040-00015
Download citation file:
Published: Ann Intern Med. 2008;148(5):403-404.
Dr. Roubenoff and colleagues and Dr. Arkfeld raise interesting points in their letters. We admit that early diagnosis of RA requires a combination of anti-CCP testing and other new biological markers or diagnostic imaging tests. However, currently available studies for these are too limited to conduct meta-analysis quantitatively. The aim of our study was to clarify the diagnostic value of anti-CCP testing from studies conducted so far.
We appreciate the opinion expressed by Dr. Roubenoff and colleagues and agree that anti-CCP–positive and –negative RA may be different subsets of RA and that levels of other biological markers, such as shared epitopes, play important roles in diagnosis. However, from the currently available evidence, we believe that the sensitivity and specificity of anti-CCP testing is still crucial for diagnosing RA. First, whereas anti-CCP is widely used for diagnosing RA, tests for new genetic markers, such as shared epitopes, are still not used routinely in daily practice. Second, the number of studies evaluating shared epitopes and anti-CCP is still low, and the clinical importance of this combination needs further evaluation. As far as we know, only Berglin and colleagues (1) have reported the sensitivity and specificity for the combination of shared epitope and anti-CCP testing. They reported that the sensitivity of the combination of anti-CCP and shared epitope testing was only 28% and the specificity was only 64%. We admit that the presence of anti-CCP antibodies interacts with genetic risk factors, such as shared epitopes in the human leukocyte antigen locus (2). However, data in the same study showed that anti-CCP was 50.9% positive for shared epitope–negative patients in the North American Rheumatoid Arthritis Consortium cohort, and that study has no information for specificity. To conduct a systemic review for the diagnostic value of anti-CCP and other new biological marker levels, we need more studies.
Learn more about subscription options.
Register Now for a free account.
Copyright © 2016 American College of Physicians. All Rights Reserved.
Print ISSN: 0003-4819 | Online ISSN: 1539-3704
Conditions of Use
This PDF is available to Subscribers Only