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05 · SFO foundations · Statistiques · 05.09A · Cours 9 — Tests diagnostiques · all pages
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05.09A · Cours 9 — Tests diagnostiques

Course 9 — Diagnostic tests

Course and questions · 59 pages

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1Diagnostic Test Interpretation2RCT Key Points Recap3Course Objectives4Clinical Scenario: Suspected Cystitis
The Diagnostic Process
5Process Overview6Differential Diagnosis of Dysuria
Test Evaluation Framework
7Usefulness of a Diagnostic Test8Requirements for Evaluating a Test9Reference Test (Gold Standard)
Sensitivity and Specificity
10Basic Performance Indicators11The 2×2 Table12Possible Errors (FP and FN)13Definitions of Se and Sp14Se and Sp Formulas on 2×2 Table15Exercise: Calculate Se and Sp
Predictive Values
16Why Se/Sp Are Not Enough Clinically17PPV and NPV Definitions18Exercise: Calculate PPV and NPV19Se/Sp vs Predictive Values20SpIn and SnOut Rules
Cystitis Dipslide Example
21Clinical Scenario Revisited22Dipslide Validation Study23Dipslide 2×2 Table24Dipslide Se (73%) and Sp (94%)25Dipslide PPV (95%) and NPV (69%)
Prevalence and Predictive Values
26PPV/NPV at 25% and 10% Prevalence27PPV/NPV at 2% and 1% Prevalence28PPV/NPV vs Prevalence Graph29Low Prevalence Pitfall in Screening
Likelihood Ratios
30Statistical Test vs Lab Test Analogy31LR+ and LR− Definitions32Dipslide LR+ (12.2) and LR− (0.29)33LR Interpretation Scale
Bayes' Theorem
34Thomas Bayes Introduction35Bayes' Formula36Bayes Applied to Diagnostic Tests37Worked Example: Cystitis Odds Update38Pre-test vs Post-test Probability Graph39Frequentist vs Subjectivist Probability
40Binary Test Summary
ROC Curves
41Continuous Tests Introduction42ROC Principle: Value Distributions43Overlapping Distributions: Useless Test44Partial Separation: Useful Test45Near-Perfect Separation46ROC Construction Procedure47D-dimer Distributions for PE48D-dimer Data in 6 Categories49Threshold 500: Se=0.997, Sp=0.44650Threshold 1000: Se=0.923, Sp=0.70851Threshold 2000: Se=0.673, Sp=0.88252All Thresholds: Se/Sp Trade-off Table53D-dimer ROC Curve Plot54ROC Interpretation: Perfect vs Useless55Area Under the ROC Curve (AUC)56AUC Interpretation57ROC Curve Summary
58Key Messages59Next Course Preview