What does a Negative Likelihood Ratio (NLR) less than 0.1 signify?

A Negative Likelihood Ratio (NLR) less than 0.1 indicates strong evidence that a negative test result is effective in ruling out a disease. The NLR is calculated as the probability of a negative test result in patients with the disease divided by the probability of a negative test result in patients without the disease.

When the NLR is significantly low, it suggests that negative test results are much more common in individuals who do not have the disease compared to those who do. This strong association enhances the reliability of the test in excluding the disease when the result is negative, allowing healthcare providers to confidently rule out the condition based on a negative test result.

A high NLR signifies a greater likelihood of false negatives, but a value below 0.1 indicates a high specificity, enhancing the diagnostic utility of the test. Inadequate test sensitivity would manifest as a higher NLR rather than a very low one, thus supporting the notion that the test is performing well in ruling out the disease. Additionally, a low NLR does not imply any need for immediate intervention; rather, it provides assurance about the safety of monitoring or discharging a patient based on a negative result.