Aim: To examine correlations between immunological markers, clinical parameters and MRI data in patients with early rheumatoid arthritis (RA) and undifferentiated arthritis (UDA).
Material and methods: The study was made of 211 patients with early RA (43 males, 168 females) and 47 patients with early UDA (mean age 48.6 +/- 13.4 years), duration of the symptoms 5.5 +/- 4.5 months). RF-positive were 136 (64.5%) patients. X-ray erosions were detected in 45 (21.3%) patients. RA activity was estimated by the integral DAS28 index (by 3 parameters), function--by HAO questionnaire (Russian version). The immunonephelometric analyzer (BN-100, Dade Behring, Germany) determined concentration of C-reactive protein (CRP), IgM. Anticitrulline antibodies (ACAB) were estimated by enzyme immunoassay, the upper limit of the norm was 5.0 U/ml. MR imaging (MRI) of both the wrists in RA patients was made on the 0.2 T Artoscan unit, the assessment was made with the reference atlas OMERACT-RAMRIS.
Results: IgM and ACAB levels were much higher in RA than in UDA. Among the patients positive by both tests (RF+ACAB) 95.2% had a typical clinical picture and RA diagnosis while 60% patients negative by RF and ACAB had UDA (p < 0.001); among patients positive by one of the tests the ratio UDA to RA was 1:2 (32.6 and 67.4%). In RA patients with very high ACAB (> 100 U/ml) CRP reached 38.10 +/- 48.29 mg/l while in negative ACAB--17.07 +/- 19.34 mg/l (p = 0.016). Wrist MRI detected synovitis and bone erosions in 93 and 66% cases, respectively. High ACAB level (> 100 U/ml) and CRP levels were associated with high DAS28, RF IgM and MRI erosions number.
Conclusion: RF and ACAB patients are characterized by a typical RA picture in the disease onset (specificity 93.6%). MRI detects synovitis in the wrist joints in 93 and erosions in 66% early RA patients. Combination of high ACAB and CRP levels is associated with high RA activity, RF IgM and great number of erosions according to MRI and may serve a marker of a severe disease course.