Sensitivity calculation — FRCA Primary MCQ

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ModerateStatistics and Evidence-Based MedicineSensitivity calculationFRCA Primary

A new test for perioperative myocardial injury is compared with the reference troponin assay in 400 patients. Results are: true positives 72, false positives 18, false negatives 8 and true negatives 302. What is the sensitivity of the new test?

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Correct answer: B — 78%

Sensitivity is true positives divided by all patients with disease: 72/(72+8)=90%. The tempting error is to divide by all positive test results, which gives the positive predictive value. Specificity would be 302/(302+18). The teaching point is to define the denominator before calculating diagnostic test performance.

Reference: RCoA Primary FRCA Syllabus 2026; Altman Practical Statistics for Medical Research