Meta-Analysis Finds Weakness in Statistical Robustness of MIGS Studies

Understanding whether statistically significant results are robust or “fragile” in MIGS trials has important implications. Clinicians interpreting trial data may overestimate treatment effectiveness if apparent significance relies on only a few participants’ outcomes. Regulatory authorities and guideline committees might also benefit from recognizing fragility as a measure of evidence strength when assessing emerging surgical technologies. Photo: Sepideh Omidghaemi, OD. Click image to enlarge. Although the adoption of minimally invasive glaucoma surgery (MIGS) has been rapid, the strength and consistency of its evidence base remain uncertain. Medical researchers sometimes use a concept called fragility metrics to provide useful context for interpreting trial outcomes that are reported as “statistically significant.” A recent study in American Journal of Ophthalmology provided a clearer understanding of the reliability of MIGS trial data and identified areas where methodological improvements were needed by conducting a fragility analysis of the literature.The work was performed by a British, Australian and German research team that included members from Moorfields Eye Hospital, University College London, the University of New South Wales and University Medical Center Hamburg. In their systematic review of 16 randomized controlled trials, their findings implied that the current body of evidence on MIGS shows variable statistical robustness.“Several systematic reviews have noted that the overall certainty of evidence supporting MIGS remains moderate to low, mainly due to imprecision, lack of masking, incomplete allocation concealment and high attrition rates,” wrote the researchers in their paper. “Furthermore, a large proportion of trials report marginally significant outcomes without proper adjustment for multiple testing or loss of follow-up, raising concerns about the reproducibility of these findings.” Under these circumstances, small changes in individual outcomes of study subjects can be overweighted in the calculation of statistical significance by the p-value method, potentially swinging the final determination one way or the other.The fragility index (FI) represents the minimum number of patient outcome changes required to convert a statistically significant result into a non-significant one. A low fragility index indicates that the reported significance is highly dependent on only a few outcome events and, therefore, statistically fragile. The fragility quotient expands on this concept by adjusting the fragility index for the total sample size, enabling comparisons across different trial scales. An in-depth explanation of fragility metrics can be found here. This team’s meta-analysis comprised 4,562 participants who met the inclusion criteria. The median sample size was 236.5, with a median follow-up of 24 months. The mean fragility index was 9.4, and the mean fragility quotient was 0.031, indicating that only approximately 3% of participants would require a different outcome to render results non-significant. “These results indicated that while fragility index values tend to rise with trial size and event frequency, fragility quotient values remained consistently low across the MIGS literature, highlighting the inherent statistical fragility of reported outcomes,” the study authors wrote in their paper.Three trials (18.8%) had an FI of 0, indicating that reversing a single event would eliminate statistical significance. In six studies (37.5%), the fragility index was less than or equal to the number of participants lost to follow-up, suggesting vulnerability to attrition bias.“Consistent use of fragility metrics alongside traditional statistical measures could improve transparency, enable meaningful comparisons across studies and encourage more balanced interpretation of surgical trial data,” the researchers advised.Click here for the journal source. Ansari AS, Jung M, Hamdan A, et al. Assessing the fragility of statistically significant outcomes in randomized controlled trials of minimally invasive glaucoma surgery (MIGS). Am J Ophthalmol. February 23, 2026. [Epub ahead of print]. This article was developed by the editorial staff in conjunction with experts in the field. In the process, AI may have been among the editorial tools used to meet the goals of human editors, who approved all content.