DEVELOPMENT AND EVALUATION OF FUZZY CRITERIA FOR THE DIAGNOSIS OF RHEUMATOID-ARTHRITIS

In 1987, the American Rheumatism Association issued a set of criteria for the classification of rheumatoid arthritis (RA) to provide a unifo rm definition of RA patients. Fuzzy set theory and fuzzy logic were us ed to transform this set of criteria into a diagnostic tool that offer s diagnoses at different levels of confidence: a definitive level, whi ch was consistent with the original criteria definition, as well as se veral possible and superdefinite levels. Two fuzzy models and a refere nce model which provided results at a definite level only were applied to 292 clinical cases from a hospital for rheumatic diseases. At the definite level, all models yielded a sensitivity rate of 72.6% and a s pecificity rate from 73.3% to 85.6% and from 83.6% to 87.0%. At the su perdefinite levels, sensitivity rates ranged from 39.0% to 63.7% and s pecificity rates from 90.4% to 95.2%. Fuzzy techniques were helpful to add flexibility to preexisting diagnostic criteria in order to obtain diagnoses at the desired level of confidence.