Background To date, due to the large variability in its clinical manifestations, early identification of rheumatoid arthritis (RA) relies on practice-based evidence. Moreover, this variation hampers the comparability and accurate stratification of the base population within and between RA trials. In 2010 the ACR/EULAR working group developed RA classification criteria that were primarily intended for research purposes. Despite its use in scientific settings, one can speculate on the effectiveness of these criteria when used in the routine clinical practice of diagnosing RA.
Objectives In this study we aimed to investigate the degree of concordance between the diagnosis of RA in routine clinical practice and the ACR/EULAR 2010 classification criteria.
Methods All patients who received a diagnosis of RA between 2010–2016 within our hospital were identified according to the financial diagnosis treatment combination (DTC) code, which corresponds to the ICD-10. Clinical and demographic data were extracted from our digital patient records of which 10% of the data were cross-checked by random selection. In retrospect we collected variables at time of RA diagnosis such as: number and type of swollen/painful joints, inflammatory markers, rheumatoid factor (RF), anti-citrullinated protein antibody (ACPA), disease duration and patients primary/secondary/tertiary diagnosis according to the rheumatologist. Additionally, all patients were classified according to the ACR/EULAR 2010 criteria for RA. The degree of concordance was determined by descriptive statistics.
Results The database included 977 patients with a DTC RA of which 673 (69%) had RA according to the rheumatologist. From the patients who were clinically diagnosed with RA, 463 (69%) fulfilled the ACR/EULAR 2010 criteria (see figure 1), this is 47% of the total DTC RA patients. The majority of the population was female (72%) and the mean age was 59. A number of 161 (24%) patients were diagnosed with RA according to the rheumatologists, but did not fulfil the ACR criteria. These patients had less inflammation, were more often RF and/or ACPA negative, and had less involved joints. About 5% of the data were missing.
Conclusions It can be concluded that the DTC codes are not the most reliable source of information in terms of the diagnosis. There is a discrepancy between the DTC code, the diagnosis according to the rheumatologist and the classification criteria. The degree of concordance between rheumatologist and the ACR criteria is comparable to the numbers described in literature. Since in our practice aspects of the ACR classification are used for diagnostic purposes, we will investigate factors that drive the specificity. Furthermore, reasons for the ICD-10/ DTC and final diagnostic mismatch is of great importance and will be studied as well. These factors will indicate opportunities on the use of the ACR/EULAR criteria in clinical practice.
Disclosure of Interest None declared
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