Fragility Index and Fragility Quotient in Statistically Significant Randomized Controlled Trials in Plastic Breast Surgery

Abstract

Background: The fragility index (FI) was conceived as an adjunct to the P value, signifying the strength of statistically significant results. The index states the minimal number of patients whose outcome must be changed from “event” to “nonevent” for the results to be statistically nonsignificant. The FI was applied in various medical specialties to assess the robustness of results presented in studies. We aim to assess the robustness of statistically significant results in studies on plastic surgery of the breast and determine factors correlated with studies deemed fragile. Methods: A systematic literature review of PubMed databases using designated keywords was performed. Background characteristics were extracted from the studies, alongside the significance of outcomes. FI and fragility quotient were calculated for each analyzed outcome and correlated with various baseline characteristics. Results: FI and fragility quotient were both significantly correlated only with the P value of the analyzed outcomes. However, grouping studies based on the P value into three categories did not demonstrate a difference in FI. Comparisons of fragile and robust studies did not demonstrate a statistically significant change in terms of baseline variables, except for the mean P value of the outcome. Conclusion: Statistically significant results of randomized controlled trials in plastic surgery of the breast suffer from extensive fragility, and researchers should critically implement their conclusions in their practice.