Objectives To evaluate bone erosions of MTP5 joints in early rheumatoid arthritis (RA) patients (pts) without structural radiographic changes by echosonography and to investigate clinical importance of autoantibodies against citrullinated peptides/proteins (ACPA) and rheumatoid factor (RF) in its detection.
Methods A group of 120 patients (85 female) with early RA (≤1 year duration, mean duration 5.4 month, (Eular 2010 classification criteria) were enrolled in the cross sectional study. None of the patients had erosions on radiographs of hands and feet and were not previously treated with DMARDs and/or glucocorticoid. Ultrasound (US) examination of MTP5 joints was performed by Esaote My Lab 70 machine equipped with 8-18 MHz linear probe. Finding of bone erosion was defined according to OMERACT US group definition. The following laboratory parameters in sera of pts were monitored: presence and concentration of ACPA, presence of RF, erythrocyte sedimentation rate (ESR) and level of CRP. Collected data were analyzed in SPSS 16 system.
Results A 240 MTP5 joints out of 120 pts were assesed by US.The MTP5 bone erosion was found at 74 (61.7%) pts. Among 120 pts 88 pts were ACPA positive with 257.1 IU/ml mean concentration and 83 pts were RF positive. There was no statistically significant difference between group of pts with and without US detected bone erosions regarding age of pts (56.9 yr. vs 52.5 yr, p=0.333), duration of RA (5.8 vs 4.8 months, p=0.712) and ESR (60.2 vs 50.5, p=0.825). Patients with MTP 5 US detected bone erosion had statistically significant higher concentration of ACPA than pts without US detected bone erosions, (323.8 vs 151.3, p=0.005) and higher level of CRP (39.7 g/l vs 25.3 g/l, p=0.024). Sixty-one ACPA positive pts and 13 ACPA negative had US detected MTP5 bone erosions in opposite to 27 ACPA positive and 19 ACPA negative pts without them. The difference was statistically significant (p=0.01). Fifty-five pts with MTP5 US detected bone erosion had positive RF and 19 pts had RF negative in contrast to 28 RF positive and 18 RF negative pts without them. The difference was not statistically significant (p=0.155). The 0.66 value of the area under the ROC curve was found for ACPA and 0.57 value for RF. The 66% sensitivity and 61% specificity of ACPA and 74% sensitivity and 29% specificity of RF was established in detection of US MTP5 bone erosion for value on 174 of cut off.
Conclusions Erosions of MTP 5 joints were detected by echosonography in 62% of early rheumatoid arthritis patients without erosions visible on X-ray. ACPA positivity was weakly associated with presence of MTP5 erosions. There was no significant correlation between US bone erosions and RF positivity.
Disclosure of Interest None declared