1 / 11

Understanding Screening Tests: Sensitivity, Specificity, and Predictive Values in Diagnostics

This lesson delves into the critical concepts of screening tests within the context of diagnosis. It explains key metrics such as sensitivity (Se), specificity (Sp), and positive predictive value (PPV), highlighting their significance in evaluating test effectiveness. By employing Bayes’ theorem, we illustrate how positive results can influence the probabilities of having a condition. Using sample calculations, we demonstrate how these metrics, such as Se=.95 and Sp=.90, impact clinical decision-making regarding potential conditions and false positives/negatives.

clark-benjamin
Download Presentation

Understanding Screening Tests: Sensitivity, Specificity, and Predictive Values in Diagnostics

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Lesson #10 Screening Tests

  2. D D’ TP + FP FN - TN = P( + | D ) Sensitivity = Se = P( - | D’ ) Specificity = Sp

  3. 95 20 5 180 Ca no Ca + - 100200 Se = .95 Sp = .90

  4. 95 200 5 1800 Ca no Ca + - 1002000 Se = .95 Sp = .90

  5. Positive Predictive Value (PPV) PPV = P( D | + ) Not the same as Se!

  6. The simplest form of Bayes’ Theorem is: PPV = P(D | +)

  7. PPV = P(D | +)

  8. Se p 1-Sp 1-p PPV = P(D | +)

  9. PPV Se = .95 Sp = .90 p = .02 = .162

  10. Ca no Ca 95 95 200 20 + 5 5 1800 180 - 100200 Ca no Ca + - 1002000

  11. + P(Ca and +) = P(TP) Se = .95 = (.02)(.95) = .019 Ca .05 .02 - P(+) = .117 + .98 P(No Ca and +) = P(FP) .10 = (.98)(.10) = .098 No Ca Sp = .90 -

More Related