Magnetic resonance imaging (MRI) is more reliable than anticyclic citrullinated peptide (anti-CCP) antibody testing for diagnosing patients in the early stages of rheumatoid arthritis (RA), study findings indicate.
Javier Narváez and colleagues, at the University of Barcelona in Spain, compared the two diagnostic approaches for RA in patients with early inflammatory arthritis and a strong clinical suspicion of RA, but equivocal findings on initial testing.
They recruited 40 patients without rheumatoid factor or erosions on radiography and performed both anti-CCP testing and contrast-enhanced MRI of the most affected hand.
The criterion for a positive diagnosis of RA was either the presence of anti-CCP antibodies, or MRI results showing synovitis with bone erosions or bone marrow edema. Seven and 33 patients met these criteria, respectively.
At 1-year follow-up, patients were reviewed and assigned a diagnosis according to the American College of Rheumatology criteria. The final diagnoses were RA in 31 patients, undifferentiated arthritis in seven patients (five self-limiting), and psoriatic arthropathy and antisynthetase syndrome in one patient each.
Writing in the journal Seminars in Arthritis and Rheumatism, Narváez et al reveal that anti-CCP testing had a specificity of 100% and a sensitivity of 23% for the identification of seronegative RA, whereas MRI had a specificity of 78% and a sensitivity of 100%.
The study authors remark that the early diagnosis and treatment of RA is critical to allow early treatment and thereby prevent permanent disability.
“The challenge in early RA is to distinguish this disease from other disorders that mimic it or are transient or are not expected to lead to destructive arthritis,” they write.
“Our results suggest that both [anti-CCP antibody determination and MRI] are helpful but that the diagnostic effectiveness of MRI for identifying seronegative RA is greater.”