To evaluate the validity, responsiveness, and predictive value of power Doppler ultrasonography (PDUS) monitoring of response to tumor necrosis factor (TNF) blocking agents in rheumatoid arthritis (RA).
Three hundred sixty-seven RA patients were prospectively recruited at 25 Spanish centers; complete clinical, laboratory, and PDUS data were obtained on 278 patients. The patients underwent clinical, laboratory, and PDUS assessment at baseline and after 1, 3, 6, and 12 months of anti-TNF treatment, and radiographic assessment of the hands and feet at baseline and 12 months. The Disease Activity Score in 28 joints (DAS28) was recorded at each visit. PDUS examination included 86 intraarticular and periarticular sites in 28 joints. US synovial fluid (SF), synovial hypertrophy (SH), and PD signal were scored in all synovial sites. US count and index for SF, SH, and PD signal were obtained. Sensitivity to change of the PDUS variables was assessed by estimating the smallest detectable difference (SDD) from the intraobserver variability.
A significant parallel improvement in DAS28 and PDUS parameters was found at followup assessment (P < 0.0005 for within-subject between-visit changes). The SDD for PDUS parameters was lower than the mean changes throughout followup. Time-integrated values of US joint count for PD signal and rheumatoid factor (RF) showed predictive value in relation to progression of radiographic erosion (R = 0.64), and time-integrated values of US joint count for PD signal, RF, and erythrocyte sedimentation rate were predictors of progression of the total radiographic score (R = 0.59).
These findings indicate that PDUS is a valid method for monitoring response to anti-TNF therapy in RA; results obtained by PDUS are reproducible and sensitive to change. PDUS findings may have predictive value in relation to radiologic outcome.