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Recently, a joint working group of the American College of Rheumatology (ACR) and the European League Against Rheumatism (EULAR) was formed to develop new classification criteria for rheumatoid arthritis (RA),1 2 and announced the 2010 ACR/EULAR classification criteria for identifying patients with early RA.3 The present study was performed in order to determine whether the newly developed 2010 ACR/EULAR criteria would include patients who were previously diagnosed with early RA according to the 1987 ACR criteria.4
We studied 170 patients with early RA patients, who had been classified as having RA according to the 1987 ACR criteria. Early RA was defined by less than 12 months of symptoms. The 2010 ACR/EULAR criteria were applied to patients at the exact time point when they were identified as fulfilling the 1987 ACR criteria. The clinical characteristics and laboratory findings were assessed. Our study protocol was approved by the Institutional Review Board of Severance Hospital, Yonsei University Health System, Seoul, Korea.
The mean age of the patients was 49.4±14.0 years, and 129 patients (76.0%) were women. The mean symptom duration was 5.4±3.6 months. Mean numbers of tender and swollen joints were 9.0±6.7 and 6.2±4.6, respectively. Rheumatoid factor (RF) was positive in 146 (85.9%) patients and 139 (81.8%) patients were anti-cyclic citrullinated peptide (anti-CCP) positive. In total, 152 (89.4%) patients were seropositive for RA, that is, positive for either RF or anti-CCP.
According to the 2010 ACR/EULAR criteria, 156 (91.8%) patients were classified as having RA and 14 (8.2%) patients did not have RA. Table 1 shows the results of the application of the new criteria on patients. Patients with RA, according to the new criteria, most frequently demonstrated a score of 7, followed by 8. Among 152 seropositive patients, only 1 (0.6%) patient was not classified as having RA by the 2010 ACR/EULAR criteria. However, among 18 seronegative patients, who did not have either RF or anti-CCP, 13 (72.2%) patients were not classified as having RA. Table 2 shows the characteristics of the patients who were not classified as having RA by the 2010 ACR/EULAR criteria. There were no differences in clinical characteristics, including age, sex, symptom duration, morning stiffness, number of tender/swollen joints, number of small/large joints, erythrocyte sedimentation rate and C reactive protein, between seropositive and seronegative groups.
The new criteria require more than 10 affected joints including at least one small joint to diagnose RA in seronegative RA patients. In our study, all seronegative RA patients, who satisfied the 1987 ACR criteria but not the 2010 ACR/EULAR criteria, had ≤10 affected joints. Therefore, seronegative RA patients with ≤10 involved joints might be excluded based on the 2010 ACR/EULAR criteria.
The clinical picture of patients with early RA may be different in Korea in comparison with that of the predominantly white populations of Europe and North America. However, our data are similar to those of the Leiden Early Arthritis Clinic cohort5 where 11.3% of patients who fulfilled the 1987 ACR criteria at baseline did not fulfil the 2010 ACR/EULAR criteria; 97.6% of these ‘1987 only’ patients were seronegative for RF and anti-CCP. Our results are also similar to those of Cader et al6 who found that 12.8% of early arthritis patients who fulfilled the 1987 ACR criteria at baseline did not fulfil the 2010 ACR/EULAR criteria and all of the ‘1987 only’ patients were seronegative for RF and anti-CCP.
In conclusion, the 2010 ACR/EULAR criteria did not identify more than half of the seronegative early RA patients classified by the 1987 ACR criteria. Therefore, careful attention is needed when applying the new criteria to patients with early arthritis who are negative for RF or anti-CCP.
Funding This study was supported by a grant from the Korea Healthcare Technology R&D project, Ministry of Health and Welfare, Republic of Korea (A102065).
Competing interests None.
Ethics approval This study was approved by the Institutional Review Board of Severance Hospital, Yonsei University Health System, Seoul, Korea.
Provenance and peer review Not commissioned; externally peer reviewed.
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