Fragility of randomized clinical trials comparing surgical approaches for inguinal hernia repair: a systematic review

Randomized clinical trials (RCTs) remain the reference standard for estimating causal effects of surgical interventions when appropriately designed and conducted. However, P values alone do not describe how sensitive a dichotomous statistical-significance classification is to small changes in outcome counts. The Fragility Index (FI) and Reverse Fragility Index (RFI) are post hoc descriptive metrics that quantify the number of outcome-status changes required to alter statistical significance. This study aimed to evaluate FI/RFI for inguinal hernia repair (IHR) RCT findings, assess individual complication endpoints, and examine associations with sample size and conflict-of-interest reporting.

Embase, PubMed, LILACS, and ClinicalTrials.gov were searched through June 2025 for RCTs comparing open, laparoscopic, or robotic inguinal hernia repair with dichotomous primary outcomes. FI, RFI, and sample-size-adjusted quotients were calculated from reconstructed 2 × 2 tables using two-sided Fisher exact tests. Individual complications and associations with trial characteristics were analyzed.