COMPARATIVE-STUDY OF 4 DIAGNOSIS CRITERIA SETS FOR MIXED CONNECTIVE-TISSUE DISEASE IN PATIENTS WITH ANTI-RNP ANTIBODIES

Objective. To evaluate the performances of 4 sets of criteria proposed to define mixed connective tissue disease (MCTD): the criteria of Sha rp, Alarcon-Segovia, Kasukawa, and Kahn. As anti-UI-RNP antibodies app ear indispensable to establish the diagnosis of MCTD, we wished to ree valuate these sets of criteria in patients who all had anti-U1-RNP ant ibodies. Methods, We analyzed clinical and biological data to find whi ch diagnostic criteria were met by 45 patients with anti-U1-RNP antibo dies. We tested criteria for rheumatoid arthritis, systemic lupus eryt hematosus, systemic sclerosis, polymyositis, Sjogren's syndrome, and 4 sets of criteria for MCTD. Results. The criteria that best identified patients with MCTD were those proposed by Alarcon-Segovia, with 62.5% sensitivity and 86.2% specificity, comparable to Kahn's criteria. The overlap with other connective tissue diseases was found to be 16%. Th ese results could be improved by using the term ''myalgia'' instead of ''myositis'' in the definition. This increased sensitivity to 81.3%, with no decrease in specificity. Conclusion, Alarcon-Segovia's and Kah n's criteria are the best classification criteria to define MCTD.