Statistical Evaluation of Test Accuracy Studies for Toxoplasma gondii in Food Animal Intermediate Hosts

The availability of accurate diagnostic tests is essential for the detection andcontrol of Toxoplasma gondii infections in both definitive and intermediatehosts. Sensitivity, specificity and the area under the receiver-operating characteristic(ROC) curve are commonly used measures of test accuracy for infectiousdiseases such as toxoplasmosis. These test performance characteristics areimportant considerations when selecting from among a group of tests for a specifictesting purpose. In this study, we reviewed statistical approaches to evaluationof tests for toxoplasmosis with and without a gold-standard (reference)test, including use of ROC analysis and likelihood ratios which retain the diagnosticinformation inherent in a quantitative test result. We use previously publisheddata from a comparison of the accuracy of serological tests for swinetoxoplasmosis to demonstrate suggested methods of data analysis. We make recommendationsfor statistical analysis and reporting of test evaluation studies forT. gondii in food animals based on our own experiences and those of others.