Evaluation of the valab expert system for validation of routine hematological data

Dieter De Smet, N. Nanos, L. Smet, Serge Damiaens, Guy Van Moer, Aline De Pauw, Kristin Jochmans, Marc De Waele

Research output: Contribution to journalEditorial


Background: VALAB is a commercially available, rulebased automated validation system which submits test results and other data stored in each laboratory report to an algoritmic reasoning based on biological, demographic and clinical considerations. We evaluated the performance of VALAB for validation of routine hematological data.
Methods: 591 laboratory reports were submitted for validation to VALAB. A consensus made by a group of laboratory experts (n=7) served as the reference standard to which the dicisions of VALAB were compared in terms of sensitivity, specificity, and predictive values.
Results: VALAB automatically validated 334 (56.5%) of 591 reports. By consensus 82 reports (13.9%) should not have been validated because they needed some kind of additional revision. VALAB incorrectly validated 24 reports that needed revision (false negatives), yielding a sensitivity for VALAB of 70.7%. Specificity was 60.9%, since VALAB did not validate 199 correct reports (false positives). The positive predictive value - defined as the probability that not validated report needs revision - was 22.6% for VALAB, while the negative predictive value - defined as the probability that a validated report doesn't need revision - 92.8% for VALAB.
Conclusions: VALAB automatically validates a substantial number of laboratory reports which require additional revision (reflected in a sensitivity of ~70%), while on the other hand a lot of correct laboratory reports are held back for revision (reflected in a specificity of ~60%). Since the results of VALAB are not available for the user, there should be looked with the manufacturer for modifications according to the experts' consensus.
Original languageEnglish
Pages (from-to)85-86
Number of pages2
JournalAnnales de Biologie Clinique
Issue number2009
Publication statusPublished - 2009


  • valab


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