Trial metrics (RRR/ARR/NNT) and screening test choice

HIGH-YIELD Appears 3×

Teaching point

From event rates you can compute ARR, RRR and NNT for a treatment group; PPV/NPV apply to diagnostic tests, not therapeutic groups. A screening test to safely RULE OUT disease must be highly SENSITIVE (e.g. D-dimer for PE); specificity confirms (rules in).

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