DEVELOPMENT AND VALIDATION OF RESPONSE CRITERIA IN RHEUMATOID-ARTHRITIS - STEPS TOWARDS AN INTERNATIONAL CONSENSUS ON PROGNOSTIC MARKERS

The course of rheumatoid arthritis (RA) is highly variable, ranging fr om a mild self-limiting to a very aggressive form. To follow and predi ct the course of the disease in an individual patient, several recogni zed and proposed prognostic markers, including markers for disease act ivity, have been considered. However, no individual marker for disease activity has shown satisfactory specificity and sensitivity. Thus an index of disease activity combining several variables is needed. Respo nse criteria based on the Disease Activity Score (DAS) were developed in an open study of 227 patients with RA of recent onset. Response was defined as a combination of a significant change from baseline and th e level of disease activity attained. Good response was defined as a s ignificant decrease in DAS (>1.2) and a low level of disease activity (less than or equal to 2.4), Non-response was defined as a decrease le ss than or equal to 0.6, or a decrease >0.6 and less than or equal to 1.2 with an attained DAS >3.7. Any other scores were regarded as moder ate responses. These response criteria were adopted as the EULAR respo nse criteria and were validated, together with the WHO/ILAR and ACR re sponse criteria, in a 48 week, double-blind trial comparing hydroxychl oroquine and sulphasalazine in 60 patients. Response was evaluated aga inst radiographic damage (construct validity) and functional disabilit y (criterion validity); discriminating capacity was also assessed. EUL AR response criteria showed significant association with X-ray progres sion and functional disability, and differentiated between sulphasalaz ine and hydroxychloroquine. ACR and WHO/ILAR response criteria perform ed less well, only showing good criterion validity. Several groups are working on the prognosis of early RA and have agreed to collaborate t o test DAS and other prognostic markers to better recognize severe, pr ogressive RA, before joint damage takes place.