The performance of the knowledge-based system VALAB revisited: an evaluation after five years.

In 1988, inundated by the tedious work of validation of laboratory reports in a large hospital biochemistry laboratory, we designed VALAB, a knowledge-based system specially dedicated to this iterative function. Coping at first with a few biochemical tests, the program has been progressively expanded to forty-five common chemical tests. Simultaneously some new rules have been introduced to "weight" the conclusion in different circumstances and rules taking into consideration some clinical data have also been written. Moreover the program moved to other disciplines, pH and blood gases, haematology and coagulation. Accordingly the evaluation protocol has been modified, incorporating a new step, the consensus decision of the pathologists, operating within the initial protocol and based upon the various criteria of epidemiology. These major changes and improvements have led us to check and describe again the performance of this updated VALAB knowledge-based system.

[Computer-assisted validation system applied to hematology: Valab-hemato]. / Système de validation assistée par ordinateur appliqué à l'hématologie: Valab-hémato.

Validation of laboratory reports is the ultimate step before transmission of results to the clinician. The biologist checks the intrinsic consistency of the data as well as their possible medical value that is liable to lead to other investigations. Such a policy, when performed on all the data, is time-consuming, boring and uncertain. This step may be simplified by the use of a computerized expert system. The computer assisted validation system presented here concerns routine haematology data (Valab-haemato). Like its predecessor devoted to clinical chemistry (Valab-Biochem) it is based on the performance of a powerful inference engine which generates a decision-making tree for each report according to the data. This adaptability gives the system a capacity very close to human reasoning. In its haematology version the system deals with many variables including sex, age, origin of the patient (hospital ward), and the haematological data (blood cell count, differential, reticulocyte count, various information drawn from microscope examination of the blood smear as well as any report concerning the blood sample, erythrocyte sedimentation rate). Previous data are also taken into account, as well as the normal ranges, the values beyond which no result can be automatically validated and the delta-check. Some information definitely prevents validation of the results, others can be validated if they have been previously approved. Whereas the method of reasoning is fixed, all items are changeable in order to adapt the system to the type of activity of the laboratory.(ABSTRACT TRUNCATED AT 250 WORDS)

VALAB: expert system for validation of biochemical data.

In large laboratories that use "high-throughput" equipment, it is now possible to use artificial intelligence techniques to aid decision making and validation of data. This paper describes an artificial intelligence project, VALAB, that has been carried out in our laboratory. VALAB, an expert system that permits real-time validation of data, is designed to be equivalent to validation by the laboratory director. The decision produced by the expert system is based on several factors, including correlation between repeated laboratory results, physiological association between different variables, the hospital department from which the test was ordered, and the patient's age and sex. In 200 abnormal chemistry profiles randomly selected, VALAB's ability to detect abnormal cases (i.e., sensitivity = 0.75) was exceeded by only one of seven laboratory experts. However, all seven experts outperformed VALAB's measured specificity of 0.63. The VALAB system incorporates greater than 4000 rules. Operational since November 1988, it has validated greater than 50,000 medical patients' reports in real time.