Uncommon Misdiagnosis of Rheumatoid Arthritis Save

Using long-term patient data from the BARFOT study of early rheumatoid arthritis (RA) patients, researchers at the Karolinska Institute have shown that use of the ACR-1987 classification criteria was highly precise.

The BARFOT (Better Anti-Rheumatic PharmacOTherapy) study enrolled early RA patients. This analysis included 2543 patients with at least 4 follow-up visits after initial enrollment and assessment by rheumatologists.  Patients were assessed for diagnosis vs. misdiagnosis using the ACR-1987 classification criteria.

The groups were analyzed with respect to the individual classification criteria, antibodies to citrullinated proteins (ACPA), disease activity (DAS28) and radiographic changes from inclusion up to 2 years.

Ultimately, only 45 patients (1.8%) were misdiagnosed (RA-change group). When compared to the misdiagnosed patients, true RA patients (by ACR criteria) were:

• More often RF positive (64% vs 21%, p< 0.001)
• More often ACPA positive (59% vs 8%, p< 0.001)
• Fulfill more than four ACR-1987 criteria (64% vs 33%, p< 0.001)
• Had radiographic changes at baseline (RA-keep 27% vs RA-change 12%, p=0.04).

Both groups had similar degrees of disease activity (DAS28) and evidence of X-ray joint destruction.

The ACR-1987 criteria performed well in this long-term cohort.

Misdiagnosis of RA should be considered in patients not having four or more ACR-1987 criteria, especially in those who are seronegative.