What does a sensitivity level of 32 or less indicate?

Understanding Sensitivity ≤32

A sensitivity of 32 or less (expressed as 32% or 0.32) indicates a diagnostic test that will miss approximately two-thirds to three-quarters of patients who actually have the disease—this represents extremely poor test performance that is generally unacceptable for clinical use. 1, 2

What This Means Clinically

• Sensitivity of 0.32 means the test correctly identifies only 32% of patients with the disease, missing 68% of true cases (false negatives) 1
• This level of sensitivity falls far below acceptable thresholds for most clinical applications, where sensitivity typically ranges from 0.67-0.99 depending on the clinical context 1
• For comparison, clinically useful tests generally achieve sensitivities of at least 0.85-0.95 for rule-out purposes 1

Clinical Implications by Context

When High Sensitivity is Critical (Where ≤32 is Unacceptable)

• In screening or rule-out scenarios, sensitivity ≤32 would be catastrophically inadequate, as the primary goal is to avoid missing disease 2
• For conditions where missing the diagnosis leads to severe morbidity or mortality (e.g., stroke, tuberculosis, heart failure), such low sensitivity would result in unacceptable patient harm 1, 2
• The American Thoracic Society, Infectious Diseases Society of America, and CDC guidelines emphasize that when consequences of missing disease exceed those of false-positives, sensitivity must be prioritized—making a test with sensitivity ≤32 clinically inappropriate 2

The Sensitivity-Specificity Trade-off

• Tests with very low sensitivity (≤32) might theoretically have high specificity, but this trade-off is rarely justified in clinical practice 1, 2
• Even when specificity is prioritized (e.g., confirmatory testing in low-risk populations), sensitivity should not drop below 0.67-0.87 in most scenarios 1
• For example, in heart failure diagnosis, even at higher thresholds prioritizing specificity, sensitivity ranges from 0.67-0.90, never approaching levels as low as 0.32 1

Practical Examples of Acceptable Sensitivity Ranges

Rule-Out Testing (Requires High Sensitivity)

• BNP ≤100 ng/L for heart failure: sensitivity 0.95 (95% CI 0.93-0.96) 1
• NT-proBNP ≤300 ng/L for heart failure: sensitivity 0.99 (95% CI 0.97-1.00) 1
• NIHSS ≥6 for stroke/LVO detection: sensitivity 0.87 2

Confirmatory Testing (Accepts Lower Sensitivity for Higher Specificity)

• BNP 100-500 ng/L: sensitivity 0.85 (95% CI 0.81-0.88) 1
• NT-proBNP 300-1800 ng/L: sensitivity 0.90 (95% CI 0.86-0.93) 1
• CSF VDRL for neurosyphilis: sensitivity ranges 0.49-0.875 1

When Sensitivity ≤32 Might Be Reported

• At extremely high diagnostic thresholds where specificity approaches 100% but at the cost of missing most cases 1
• In research contexts examining test characteristics across multiple cutpoints, though such thresholds would never be recommended for clinical use 1
• For example, one study reported BNP ≥500 ng/L had sensitivity ranging from 0.35-0.83, with the lower bound approaching unacceptable levels 1

Critical Pitfalls

• Never use a test with sensitivity ≤32 as a standalone rule-out test, as it will miss the majority of disease cases 2
• Disease prevalence does not change test sensitivity—sensitivity remains a characteristic of the test itself, though predictive values vary with prevalence 2
• Sequential testing strategies may be required if no single test achieves adequate sensitivity, using a sensitive test first followed by a specific confirmatory test 2
• Consider whether effective treatment exists—even with perfect sensitivity, testing is only valuable if intervention improves outcomes 2