The sensitivity, specificity and predictive value of total plasma protein in the diagnosis of traumatic reticuloperitonitis.

We analyzed the value of total plasma protein in the diagnosis of traumatic reticuloperitonitis in dairy cattle using the concept of sensitivity, specificity and predictive value of a test. Cows with traumatic reticuloperitonitis surgically confirmed at the New York State College of Veterinary Medicine served as cases, while cows surgically explored for other abdominal diseases that might be confused with traumatic reticuloperitonitis during differential diagnosis were controls. The sensitivity of the total plasma protein in diagnosis of traumatic reticuloperitonitis decreased from 97% to 6.3% as the cutoff value for a positive test rose from 65 g/L to 110 g/L, while specificity increased from 11.3% to 99.1% over the same range of cutoff values. Application of these figures to predictive values positive and negative at various prevalence levels of disease is discussed. For example at the measured prevalence level of 37%, 76% of cattle with plasma protein concentrations in excess of 100 g/L had traumatic reticuloperitonitis.