Epidemiologic issues in the validation of veterinary diagnostic tests

In this review, we critically discuss the objectives, methods and limitatio ns of different approaches for the validation of diagnostic tests, We show (based on published data and our own experiences) that estimates for the di agnostic sensitivity and specificity may vary among populations and/or subp opulations of animals, conditional on the distribution of influential covar iates. Additional variability in those parameter estimates may be attributa ble to the sampling strategy. The uncertainty about diagnostic parameters i s of concern for the decision-maker in the context of clinical diagnosis or quantitative risk assessment as well as for the epidemiologist who uses te st data for prevalence estimation or risk-factor studies. Examples for the calculation of diagnostic parameters are presented together with bias-avoid ance strategies. We suggest guidelines for an epidemiologic approach to tes t validation of veterinary diagnostic tests. (C) 2000 Elsevier Science B.V. All rights reserved.