CRP and infection: Often, the diagnostic performance of the test is expressed using as summary statistics the sensitivity (proportion of infections correctly identified by the CRP test, TP/(TP+FN)=67/83=81%) and the specificity (proportion of non-infections correctly identified by the CRP test, TN/(FP+TN)=143/149=96%).9 Although widely used, these statistics do not by themselves enable the user to judge the probability that a patient who receives a particular CRP test result has infection.