The fragility of statistically significant findings from randomized trials in spine surgery: a systematic survey

Abstract Background context Randomized controlled trials (RCTs) are the most trustworthy source for evaluating treatment effects, but RCTs of spine surgery interventions often produce discordant results. The Fragility Index is a novel metric to inform about the robustness of statistically significant results. Purpose The aim was to determine the robustness of statistically significant results from RCTs of spine surgery interventions. Study design/Setting This was a systematic survey. Patient sample The sample included RCTs of spine surgery interventions. Outcome measures The Fragility Index is the minimum number of patients in a trial whose status would have to change from a nonevent to an event to change a statistically significant result to a nonsignificant result. Events refer to the occurrence of any dichotomous outcome, such as successful fusion, incident fracture, adjacent segment degeneration, or achievement of a certain functional score. A small Fragility Index indicates that the statistical significance of a result hinges on only a few events, and a large Fragility Index increases one's confidence in the observed treatment effects. Methods We systematically reviewed a database for evidence-based orthopedics and identified all the RCTs that reported at least one positive outcome (ie, p