VITAL DX v4.0 • VERIFIED QUANTITATIVE BRIEFING
Bayesian Positive Predictive Value: 90% Sens / 92% Spec / 2% Prevalence
With 90% sensitivity, 92% specificity, and 2% disease prevalence, the Positive Predictive Value (PPV) of a positive test is 18.7%.
Bayes Theorem: PPV = TP / (TP + FP) = (90% × 2%) / [(90% × 2%) + (8% × 98%)] = 18.7%.
FAQ: What is the PPV when sensitivity is 90%, specificity is 92%, and prevalence is 2%?
The Positive Predictive Value (PPV) is 18.7%, meaning 81.3% of positive results at 2% prevalence are false positives.