Evidence-appraisal glossary
Diagnostic odds ratio
The diagnostic odds ratio (DOR) is a single number summarizing how well a test separates people with a disease from those without it. It equals the odds of a positive result in diseased people divided by those odds in non-diseased people. Higher means better; 1 means useless.
Also called: DOR, diagnostic OR.
What it is
The DOR bundles a test's sensitivity and specificity into one figure. From a 2x2 table it is (true positives x true negatives) / (false positives x false negatives), equivalently the positive likelihood ratio divided by the negative likelihood ratio. It ranges from 0 to infinity: a value of 1 means the test tells you nothing, higher values mean stronger discrimination, and a value below 1 signals the result is running backwards.
How to use it when reading a study
Treat the DOR as a quick single-number comparison of overall discrimination, and note it does not shift with disease prevalence. But do not stop there. Because one number cannot tell you whether a test is better at ruling in or ruling out disease, always look for the separate sensitivity, specificity, and likelihood ratios. Check whether authors added 0.5 to empty cells, which biases the estimate, and be wary of a DOR quoted without a confidence interval. It is most useful for summarizing accuracy across studies, less useful for a bedside decision.
Read the full Reading the Evidence blog.
This is a plain-language methodology definition for reading research. It is general education, not medical advice.