For all samples run, REPCAT sets a patient classification field (PatClas) to be one of: N (normal), X (unlikely PHEO-a minor abnormality such as increased urine volume, methyldopa present, etc.
After REPCAT had run and tested each record (a process that took ~40 min for the 4321 records), 384 samples were classified as Q (abnormal--conditionally requiring follow-up) and, of these, 176 were classified as "probable PHEO.
REPCAT reports on any and all abnormal data associated with a particular sample and the associated comment is graded according to the degree to which the data diverges from normal.
In the group of patients with confirmed PHEO, 20 were assessed by REPCAT to be exclusively NE-secreting, 10 were assessed as exclusively EP-secreting, and the remaining 12 were assessed as "mixed" secretors.
The maximum number of false-positive (possible PHEO) samples classified by REPCAT, calculated by subtracting the number of actual positive PHEO samples from the total number of "Q"s, was 208 (5%), and the maximum number of false positives classified probable PHEO was 86 (2%).
REPCAT has been in full-time use in our laboratory for 5 years and has proven a fast, highly functional tool, providing the performance of an experienced expert in the domain of investigation of PHEO.
In many of these cases, however, the initial interpretive report provided by REPCAT was helpful in speeding the follow-up procedure.
Aside from its accuracy and efficiency as an expert system, we believe that by its incorporation into a database application, REPCAT represents a simple approach to practical expert system development in a relatively narrow domain.