Diagnostic research is the goal of a diagnostic test is to provide information on the probability of disease. In this article, we review the principles of diagnostic test characteristics, including sensitivity, specificity, positive and negative predictive value, receiver operating characteristics curves, likelihood ratios, and interval likelihood ratios. We illustrate how interval likelihood ratios optimize the information that can be obtained from test results that can take on >2 values, how they are reflected in the slope of the receiver operating characteristics curve, and how they can be easily calculated from published data.
Diagnostic research on Pediatric hospitalists uses diagnostic tests and clinical prediction rules to decrease diagnostic uncertainty and inform a child’s management. Nevertheless, health care providers often recommend tests without considering each test’s diagnostic characteristics,1 and over testing can lead to false-positives and -negatives, incorrect diagnoses, and overtreatment.2 Understanding test characteristics can enhance pediatric hospitalists’ ability to practice evidence-based medicine.
Some diagnostic tests have naturally dichotomous results, whereas other tests can be made into dichotomous tests by selecting a cutoff value. Dichotomous tests provide a binary answer to the question of whether a patient has the disease.
Diagnostic research is among individuals without the disease, specificity is the probability that a test will be negative. Specificity is calculated as TN/(TN + FP). If the nitrite test has a 98% specificity, this means that, among 100 children who do not have UTIs, 98 will have a negative nitrite test and be correctly identified as not having a UTI and 2 will have a falsely positive result. A false-positive result may worry the individual, waste limited resources, and lead to unnecessary additional tests or treatments. Tests that have perfect specificity will not have any false positives. Specificity can only be calculated among people who do not have the disease. Sensitivity and specificity are generally assumed unaffected by the pretest probability (the probability of disease before learning the test result), although this is not always the case. Use APA referencing style.