2010 RA Criteria Misclassify 45% of Patients In Routine Practice

Oct 05, 2012

Be vigilant in testing for other conditions when applying the latest screening rules for RA. Nearly half of people classified as having rheumatoid arthritis by new criteria actually had other conditions, in a study of consecutive patients referred to a university clinic by their primary rheumatologists.

The 2010 ACR/EULAR criteria for the detection of rheumatoid arthritis (RA) were created to improve early detection of the condition. But they may have gone too far in that direction, say the authors of a new study that tests the 2010 standards against the earlier 1987 ACR version, apparently for the first time in routine clinical practice.

Applied to 126 patients referred to the NYU Hospital for Joint Diseases by primary rheumatologists in the eight months ending in April 2011, the newer criteria were slightly more sensitive than the 1987 set (97% versus 93%), but far less specific (55% compared to 76%). The study included patients referred for to the clinic after being initially diagnosed by the primary rheumatologist (the "gold standard" in this study) for a wide variety of rheumatologic conditions.

After referral, a single NYU rheumatologist applied both sets of criteria, followed by 10 laboratory tests accepted for RA assessment as well as the appropriate radiological studies. Patients were followed for an average of six months afterwards.

The new criteria state that RA should be considered in the presence of a swollen joint after "‘…all other possible diagnoses have been eliminated," a somewhat meaningless directive (the authors observe) in that, if it were straightforward to eliminate all other reasonable possibilities, the RA criteria themselves would not be necessary.

This is not the first study to suggest that the 2010 criteria are too nonspecific to be completely useful. They may be beneficial in speeding the path from primary care to referral to a rheumatologist, the authors say. But "(w)hile a patient may benefit from early DMARD therapy no matter what type of inflammatory arthritis they may have, their true underlying disease might then be masked which could lead to harmful consequences" such as unknown prognosis, comorbidities, and inappropriate treatment.

The bottom line? Upon referral for suspected RA, say the NYU team, use special care in testing a patient for alternative diagnoses before concluding firmly, based on the 2010 criteria, that he or she truly has rheumatoid arthritis.

The article "Utility of the new rheumatoid arthritis 2010 ACR/EULAR classification criteria in routine clinical care" appears in BMJ Open Access.