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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