Fragility indices for only sufficiently likely modifications

Benjamin R Baer*, Mario Gaudino, Mary Charlson, Stephen E Fremes, Martin T Wells

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The fragility index is a clinically meaningful metric based on modifying patient outcomes that is increasingly used to interpret the robustness of clinical trial results. The fragility index relies on a concept that explores alternative realizations of the same clinical trial by modifying patient measurements. In this article, we propose to generalize the fragility index to a family of fragility indices called the incidence fragility indices that permit only outcome modifications that are sufficiently likely and provide an exact algorithm to calculate the incidence fragility indices. Additionally, we introduce a far-reaching generalization of the fragility index to any data type and explain how to permit only sufficiently likely modifications for nondichotomous outcomes. All of the proposed methodologies follow the fragility index concept.
Original languageEnglish
Article numbere2105254118
Number of pages12
JournalProceedings of the National Academy of Sciences
Issue number49
Early online date30 Nov 2021
Publication statusPublished - 7 Dec 2021


  • Evidence measure
  • Fragility index
  • Interpretability
  • P value
  • Statistical significance


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