title: Latent class regression models for simultaneously estimating test accuracy, true prevalence and risk factors for Brucella abortus.
abstract: In 2003/2004 a field trial was conducted in Northern Ireland to assess the diagnostic accuracy of six serological tests for bovine brucellosis caused by Brucella abortus. Whereas between-test comparisons have been used to calculate test performances so far, the present study used a latent class approach to estimate diagnostic test accuracy parameters in the absence of a gold standard for these six tests simultaneously and to estimate the true prevalence, while accounting for clustering in the study population and risk factors for true prevalence. Results obtained in this study with regard to prevalence, sensitivity and specificity were largely in accordance with previous findings. Screening tests (SAT and EDTA) appeared to be the most sensitive; however, at low prevalences the EDTA and CFT showed the highest positive predictive values of all investigated tests. The specificities and negative predictive values of all diagnostic tests were found to be very high. Differences of prevalence between three groups of the study population with different risk of exposure could be attributed to the mode of sampling indicating that a more risk-based sampling will result in a higher prevalence than a cross-sectional sampling mode. Age, dairy status and history of abortion were shown to influence the prediction of the latent true infection status.
authors.affiliation: Department of Biometry, Epidemiology and Information Processing,University of Veterinary Medicine Hannover and WHO Centre for Research and Training in Veterinary Public Health,Hannover,Germany.
authors.forename: A
authors.initials: A
authors.lastname: Campe
authors.affiliation: Department of Veterinary Tropical Diseases,Faculty of Veterinary Science,University of Pretoria,South Africa.
authors.forename: D
authors.initials: D
authors.lastname: Abernethy
authors.affiliation: Veterinary Epidemiology Unit,Department of Agriculture and Rural Development,Belfast,Northern Ireland.
authors.forename: F
authors.initials: F
authors.lastname: Menzies
authors.affiliation: Federal Institute for Risk Assessment,Dept. Exposure, Germany, and University of Veterinary Medicine,Hannover,Germany.
authors.forename: M
authors.initials: M
authors.lastname: Greiner
mesh_terms: D000818:Animals; D002003:Brucella abortus / Q000302:isolation & purification*; D002007:Brucellosis, Bovine / Q000453:epidemiology*; D002417:Cattle; D003430:Cross-Sectional Studies; D003955:Diagnostic Tests, Routine / Q000379:methods*; D005260:Female; D008297:Male; D009660:Northern Ireland / Q000453:epidemiology; D011237:Predictive Value of Tests; D015995:Prevalence; D012307:Risk Factors; D012680:Sensitivity and Specificity; D012698:Serologic Tests / Q000379:methods*
keywords: Bovine brucellosis; covariates; diagnostic tests; prevalence; test accuracy