Approach to a hospital-based application of a medical expert system.

CADIAG-2 is a data-driven fuzzy medical expert system built for computer-based consultation in internal medicine. It has been integrated into the medical information system WAMIS of the Vienna General Hospital. Through the integration, CADIAG-2 is able to access patient data and laboratory test results already collected in the central patient database of WAMIS. CADIAG-2 operates in two subsequent phases: (1) as an automatic screening procedure for detecting pathological states in the patient, for generating diagnostic hypotheses, and for proposing further useful examinations; and (2) as an on-line consultation system for the clinician to assist him in clarifying patients' disorders completely and in great detail. At present, CADIAG-2 is subject to extended clinical trials. There are four application areas: rheumatic diseases, pancreatic diseases, gall bladder and bile duct diseases and colon diseases. First results on the performance of CADIAG-2 based on the evaluation of about 500 cases were obtained. In this paper, the principal goals, main components and concepts of CADIAG-2, and the experience gained until now are discussed.