Physicians at a tertiary care center are evaluating a novel immunoassay for diagnosing acute mesenteric ischemia. To determine the test's clinical utility, they apply it to a cohort of patients presenting with acute abdominal pain.
Among patients who are ultimately diagnosed with acute mesenteric ischemia via angiography, the immunoassay returns a positive result in cases. In another group of patients whose abdominal pain is confirmed to be non-ischemic in origin, the immunoassay is positive in cases.
Based on these findings, what is the positive likelihood ratio of this novel immunoassay?
Answer: 8.5
Answer
8.5
The positive likelihood ratio () is calculated by dividing a test's sensitivity by its false positive rate (). The sensitivity is the proportion of true positives among all those with the disease (). The false positive rate is the proportion of false positives among all those without the disease (). Dividing by yields . This indicates that a positive test result is 8.5 times more likely to be observed in a patient with acute mesenteric ischemia than in a patient without it.
Step-by-Step Solution
Key Concept
The positive likelihood ratio () indicates how much more likely a positive test result is to occur in a patient with the disease compared to a patient without the disease, calculated as Sensitivity / ().