RESUMEN
We performed a prospective clinical study to select cut-off points for total plasma protein (TPP) and plasma fibrinogen (PF) to differentiate between traumatic reticuloperitonitis (TRP) and other gastrointestinal diseases with similar clinical signs, and to estimate the dependence and accuracy of TPP and PF when used in series or in parallel. TPP and PF were estimated preoperatively by refractometry in 93 cattle with TRP and 65 cattle with gastrointestinal diseases such as vagus indigestion (n = 16), liver abscesses (n = 17), omasal impaction (n = 19) and Johne's disease (n = 13). Three different cut-off points were selected by two-graph receiver-operating characteristic (TG-ROC) analysis for TPP and PF. Conditional covariances were calculated as a measure of dependence between sensitivities and specificities of TPP and PF. The cut-off points of 7.22, 7.78 and 8.82g/dl for TPP and 622, 691 and 766mg/dl for PF were suggested by TG-ROC based on different requirements of test performances. There was moderate negative dependence between sensitivities of TPP and PF at the 8.82g/dl and 766mg/dl cut-off points, and mild negative dependence between their specificities at the 7.78g/dl and 691mg/dl cut-off points, respectively. Acceptable accuracy (98 or 86% specificity with 62 or 88% sensitivity, respectively) was obtained with serial interpretation of the tests.
