Assessing the Robustness of Randomized Controlled Trials on Neuromonitoring in Thyroid Surgery: Utilizing the Fragility and Reverse Fragility Index

Abstract

Purpose The Fragility Index (FI) and Reverse Fragility Index (RFI)) are novel metrics that have been developed to evaluate the robustness of RCTs. The aim of this study was to assess the robustness of RCTs, in the use of intraoperative neuromonitoring (IOMN) in the thyroid surgery field, using FI, RFI, and their respective fragility quotients. Methods A Systematic search was conducted based on the PRISMA which utilized MEDLINE, EMBASE, Cochrane Library, and Web of Science databases. Inclusion criteria included RCTs related to the IONM in the thyroid surgery with dichotomous outcome measures and 1:1 allocation. Fragile results were defined as those with an FI or RFI equal to or less than the number of patients lost to follow-up or those with an FI or RFI less than 3. Results There were 8 RCTs that met our criteria with 2473 patients with 4607 nerves at risk. Among them, 2 (25%) were positive RCTs (p < 0.05) and 6 (75%) were negative RCTs (p > 0.05). The median FI was 2 (IQR 0–2). The median RFI was 3.5 (IQR 1.6–6). Based on the relationship between an FI/RFI ratio of less than 3, two (25%) studies were considered fragile. Furthermore, based on the relationship between FI/RFI and the number of patients lost during follow-up, 4 (50%) studies were considered fragile. Conclusions Using the new metrics, FI and RFI, the RCTs that did not demonstrate superiority with the use of IONM in thyroid surgery were more robust than those that did show superiority. However, controversy regarding the utility of IONM is not closed