Using the ID3 Algorithm to find Discrepant Diagnoses from laboratory Databases of Thyroid Patients

Abstract

Rare cases are a central problem when an expert system is constructed from example cases with machine learning techniques. It is difficult to make a decision support system (DSS) to cover all possible clinical cases. An inductive learning program can be used to construct an expert system for detecting cases that differ from routine cases. The ID3 algorithm and the pessimistic pruning algorithm were tested in this study: a DSS was built directly from the data of patient records. A decision tree was generated, and the cases misclassified by the decision tree as compared with the classifications of a clinician were listed on a checklist, which formed the feedback to the clinician. In clinical situations about 5-10% of functional thyroid disorders may be misclassified. At this error level, the method found over 90% of the errors with a specificity of 95%. In simple medical classification tasks this dynamic self- learning system can be used to create a DSS that can assist in the quality control of clinical decision making. Key words: expert systems; automated data processing; computer-assisted diagnosis; medical decision making; thyroid disorders. (Med Decis Making 1991;11:171- 175)