Objective: To evaluate the performance of Power Doppler Ultrasonography (PDUS) compared with biological markers, in the assessment of disease activity in children with Juvenile Idiopathic Arthritis (JIA).
Methods: Forty hospital visits were studied comprising 32 patients with JIA, during one year of follow-up. Each patient underwent clinical, laboratory and ultrasound (PDUS) evaluation. The physician global assessment score on the visual analog scale (PhGA) was used as a standard for assessing disease activity, based on previous studies. The PDUS signal was scored according to a semiquantitative four grade scale (0-3).
Results: PDUS assessment of synovial vascularisation was more sensitive than erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP) in identification of the active disease: 90.4% vs. 57% and 28.5% respectively. CRP had a higher specificity (94%) in comparison with PDUS (89.5%). A significant association between clinical examination (PhGA) and PDUS score or ESR was found. Kappa statistics revealed a high level of agreement between PhGA and PDUS score (k=0.799) and a low level of agreement between PhGA and biological markers (k=0.356 and k=0.225 respectively). Patients with higher PDUS score (>or=2), ESR>or=30 mm/h or CRP>or=2 mg/dl were more likely to have active disease.
Conclusion: Laboratory tests used today are not sufficiently sensitive for the prediction of active disease. PDUS assessment of synovial vascularisation is a technique with good sensitivity and specificity, thus it may be a beneficial criteria for evaluating disease activity in JIA, completing conventional clinical examination.