Background Various definitions of remission in Rheumatoid Arthritis (RA) have been proposed. The Disease Activity Index 28 joints (DAS28) is the routinely used score. Newer tools for evaluation of RA activity include the Simplified Disease Activity Index (SDAI) and Clinical Disease Activity Index (CDAI) are available and have proved to be more stringent.
Objectives The purpose of this study was to compare the accuracy of composite scores of remission in RA patients using the absence of inflammatory activity detected by ultrasound (US) as a gold standard.
Methods Sixty seven patients followed-up for RA were recruited. B-mode and a Power Doppler (PD) US exam were assessed by a single rheumatologist who was experienced in US and blinded to the clinical and laboratory data. Twenty two joints were scanned (wrists, 10 metacarpophalangeal (MCP) and proximal interphalangeal (PIP)). SDAI and CDAI were calculated for each patient. Sensitivity, specificity and Positive Predictive value (PPV) for each score was calculated with as reference absence of Doppler signal in US. Then ROC curve were analyzed.
Results Among all patients, 30 were in remission according to the DAS28, 19 according to SDAI and 26 according to CDAI. For 19 patients there was no Doppler signal in US. The sensitivity and specificity of different remission scores considering as reference absence of joints with PD signal is showed in table 1.
The ROC curves showed that the best threshold of DAS28 was 3.2. It was 6.5 for SDAI and 8 for CDAI.
Conclusions Ours results suggest that when considering remission as an absence of Doppler signal, the DAS28 was the most sensitive and the CDAI was the most specific. The ROC curves showed threshold exceeding definition of remission.
Balsa A, De Miguel E and col. Superiority of SDAI over DAS-28 in assessing remission in rheumatoid arthritis patients using power Doppler ultrasonography as a gold standard. Rheumatology 2010.
Disclosure of Interest None declared