Fragility of statistically significant outcomes in randomized trials comparing bariatric surgeries.

BACKGROUND: Randomized controlled trials (RCTs) are regarded as high-level evidence, but the strength of their P values can be difficult to ascertain. The Fragility Index (FI) is a novel metric that evaluates the frailty of trial findings. It is defined as the minimum number of patients required to change from a non-event to event for the findings to lose statistical significance. This study aims to characterize the robustness of bariatric surgery RCTs by examining their FIs. METHODS: A search was conducted in MEDLINE, EMBASE, and CENTRAL from January 2000 to February 2022 for RCTs comparing two bariatric surgeries with statistically significant dichotomous outcomes. Bivariate correlation was conducted to identify associations between FI and trial characteristics. RESULTS: A total of 35 RCTs were included with a median sample size of 80 patients (Interquartile range [IQR] 58-109). The median FI was 2 (IQR 0-5), indicating that altering the status of two patients in one treatment arm would overturn the statistical significance of results. Subgroup analyses of RCTs evaluating diabetes-related outcomes produced a FI of 4 (IQR 2-6.5), while RCTs comparing Roux-en-Y gastric bypass and sleeve gastrectomy had an FI of 2 (IQR 0.5-5). Increasing FI was found to be correlated with decreasing P value, increasing sample size, increasing number of events, and increasing journal impact factor. CONCLUSION: Bariatric surgery RCTs are fragile, with only a few patients required to change from non-events to events to reverse the statistical significance of most trials. Future research should examine the use of FI in trial design.

Fragility of statistically significant findings from randomized trials in comparing laparoscopic versus robotic abdominopelvic surgeries.

BACKGROUND: Utility of robotic over laparoscopic approach has been an area of debate across all surgical specialties over the past decade. The fragility index (FI) is a metric that evaluates the frailty of randomized controlled trials (RCTs) findings by altering the status of patients from an event to non-event until significance is lost. This study aims to evaluate the robustness of RCTs comparing laparoscopic and robotic abdominopelvic surgeries through the FI. METHODS: A search was conducted in MEDLINE and EMBASE for RCTs with dichotomous outcomes comparing laparoscopic and robot-assisted surgery in general surgery, gynecology, and urology. The FI and reverse fragility Index (RFI) metrics were used to assess the strength of findings reported by RCTs, and bivariate correlation was conducted to analyze relationships between FI and trial characteristics. RESULTS: A total of 21 RCTs were included, with a median sample size of 89 participants (Interquartile range [IQR] 62-126). The median FI was 2 (IQR 0-15) and median RFI 5.5 (IQR 4-8.5). The median FI was 3 (IQR 1-15) for general surgery (n = 7), 2 (0.5-3.5) for gynecology (n = 4), and 0 (IQR 0-8.5) for urology RCTs (n = 4). Correlation was found between increasing FI and decreasing p-value, but not sample size, number of outcome events, journal impact factor, loss to follow-up, or risk of bias. CONCLUSION: RCTs comparing laparoscopic and robotic abdominal surgery did not prove to be very robust. While possible advantages of robotic surgery may be emphasized, it remains novel and requires further concrete RCT data.