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Exploring the fragility of meta-analyses in ophthalmology: a systematic review
Keean Nanji1,2, Jim Xie1, Amin Hatamnejad1
1Department of Surgery, Division of Ophthalmology, McMaster University, Hamilton, ON, Canada.
Objective:
The fragility index (FI) of a meta-analysis evaluates the extent that the statistical significance can be changed by modifying the event status of individuals from included trials. Understanding the FI improves the interpretation of the results of meta-analyses and can help to inform changes to clinical practice. This review determined the fragility of ophthalmology-related meta-analyses.
Methods:
Meta-analyses of randomized controlled trials with binary outcomes published in a journal classified as 'Ophthalmology' according to the Journal Citation Report or an Ophthalmology-related Cochrane Review were included. An iterative process determined the FI of each meta-analysis. Multivariable linear regression modeling evaluated the relationship between the FI and potential predictive factors in statistically significant and non-significant meta-analyses.
Results:
175 meta-analyses were included. The median FI was 6 (Q1-Q3: 3-12). This meant that moving 6 outcomes from one group to another would reverse the study's findings. The FI was 1 for 18 (10.2%) of the included meta-analyses and was ≤5 for 75 (42.4%) of the included meta-analyses. The number of events (p < 0.001) and the p-value (p < 0.001) were the best predictors of the FI in both significant and non-significant meta-analyses.
Conclusion:
The statistical significance of meta-analyses in ophthalmology often hinges on the outcome of a few patients. The number of events and the p-value are the most important factors in determining the fragility of the evidence. The FI is an easily interpretable measure that can supplement the reader's understanding of the strength of the evidence being presented.
Prospero Registration:
CRD42022377589.
Insights
The fragility index (FI) of ophthalmology meta-analyses is often low, meaning results can change with few patient outcomes. The number of events and p-value best predict this fragility.
Area of Science:
- Ophthalmology
- Medical Statistics
- Evidence-Based Medicine
Background:
- The fragility index (FI) assesses how statistical significance in meta-analyses is affected by individual patient outcomes.
- Understanding FI enhances meta-analysis interpretation and can guide clinical practice changes.
- This review specifically examines the fragility of ophthalmology-related meta-analyses.
Purpose of the Study:
- To determine the fragility index (FI) of meta-analyses within the field of ophthalmology.
- To evaluate the relationship between FI and potential predictive factors in statistically significant and non-significant meta-analyses.
Main Methods:
- Included meta-analyses of randomized controlled trials with binary outcomes from ophthalmology journals or Cochrane Reviews.
- Employed an iterative process to calculate the fragility index for each meta-analysis.
- Utilized multivariable linear regression to analyze predictors of FI.
Main Results:
- 175 meta-analyses were analyzed, with a median FI of 6.
- 10.2% of meta-analyses had an FI of 1, and 42.4% had an FI of 5 or less.
- The number of events and the p-value were identified as the strongest predictors of FI.
Conclusions:
- Many ophthalmology meta-analyses demonstrate statistical significance that is sensitive to the outcomes of a small number of patients.
- The number of events and p-value are key determinants of evidence fragility.
- The fragility index offers a valuable, interpretable metric for assessing the robustness of meta-analytic findings.
