Is a sensitivity of <=32 better than <=8 for diagnostic purposes?

Higher Sensitivity is Better for Diagnostic Testing

For diagnostic purposes, a sensitivity of <=32 is better than <=8 because higher sensitivity values improve the ability to detect disease and reduce false negatives. 1

Understanding Diagnostic Test Sensitivity

• Sensitivity refers to a test's ability to correctly identify patients who have the condition being tested for (true positives) 1
• Higher sensitivity values (such as <=32 compared to <=8) allow for detection of more cases of disease, reducing the chance of missing diagnoses 1
• In the context of genetic panel testing for Primary Ciliary Dyskinesia (PCD), studies showed that sensitivity increased from 71.9% with a 12-gene panel to 93.9% with a 32-gene panel 1

Impact of Sensitivity on Clinical Decision Making

• Tests with very high sensitivity are valuable for ruling out disease and can be used as triage tests before further harmful or costly testing 1
• When evaluating for large vessel occlusion (LVO) in stroke, using a higher sensitivity threshold (NIHSS ≥6 vs ≥10) increased sensitivity from 73% to 87%, though at the cost of lower specificity 1
• The balance between sensitivity and specificity depends on the clinical context and the relative harms of false negatives versus false positives 1

Clinical Applications Demonstrating the Value of Higher Sensitivity

• For iron deficiency anemia diagnosis, a ferritin threshold of <45 ng/mL has a sensitivity of 85% compared to only 59% sensitivity with a threshold of <15 ng/mL 1
• The American Gastroenterological Association specifically recommends the higher threshold (<45 ng/mL) to maximize sensitivity with an acceptable number of false positives 1
• In tuberculosis testing, using multiple or more comprehensive tests increases detection sensitivity, which is particularly important for high-risk conditions 1

Considerations When Selecting Test Sensitivity Thresholds

• The optimal sensitivity threshold should be determined based on the clinical context and the consequences of false negative results 1
• For serious conditions where missing a diagnosis has significant consequences, higher sensitivity (<=32) would be preferred over lower sensitivity (<=8) 1
• When testing for conditions with high morbidity or mortality, the penalty of being wrong (missing a diagnosis) is greater, justifying the use of higher sensitivity thresholds 1

Potential Trade-offs

• Higher sensitivity often comes at the cost of lower specificity (more false positives) 1
• The decision to use a higher sensitivity threshold should consider the downstream consequences of false positive results, including unnecessary further testing or treatment 1
• In some clinical scenarios, the balance between sensitivity and specificity may need to be adjusted based on disease prevalence and the relative harms of misdiagnosis 1

Practical Implementation

• When implementing diagnostic tests, clinicians should understand the sensitivity and specificity characteristics at different thresholds 1
• For screening purposes or ruling out serious conditions, tests with higher sensitivity (<=32) are generally preferred 1
• For confirmatory testing or when false positives carry significant risks, tests with higher specificity might be preferred, though this would require accepting lower sensitivity 1