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Table 1 Steps in planning a retrospective biomarker validation study

From: Planning clinically relevant biomarker validation studies using the “number needed to treat” concept

 

Stepping stone

Question format

0

Classification rule development

(Outside the scope of this article)

1

Defining the clinical scenario

Who are the patients, what are the clinical options?

2

Principal goal

What NNT s for the BestToAct and BestToWait groups would make the decision clear-cut?

3

Clinical benefit

Specifically how will patients be helped by a test that achieves these NNT’s?

4

Classification performance needed

What predictive values do these NNT’s correspond to?

5

Prospective study requirements

Given these NNT’s, how large should a prospective study be, and how long the follow-up?

6

Retrospective study requirements

Given a prevalence, what sensitivity and specificity do we hope for, and what should the sample sizes be to estimate them sufficiently?

  1. Scaffolding for NNT-guided protocol design” illustrates these study planning steps for a specific study