What is it about?

This letter from 2009 highlights issues with predictive values when disease prevalence is low. Normalizing predictive values to 50% prevalence shows cardiac CTA has a high positive predictive value, but negative results should not rule out disease.

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Why is it important?

Normalizing predictive values is important for meaningful interpretation and comparison across studies. Highlights the need for cautious interpretation of cardiac CTA's negative predictive value despite high specificity.


As a clinician reading this 2009 study, I initially thought cardiac CTA had only a moderate ability to rule out coronary artery disease based on the reported low positive predictive value. However, normalizing the predictive values to a higher prevalence paints a different picture - positive CTA has a very high predictive value for true disease, but negative results should not be relied upon alone to rule out disease confidently. Attention to predictive value normalization is crucial for appropriately interpreting and applying diagnostic test results.

Thomas F Heston MD
University of Washington

Read the Original

This page is a summary of: Detection of myocardial infarction by CT angiography, Heart, June 2009, BMJ,
DOI: 10.1136/hrt.2009.169508.
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