Paediatric surgical trials, their fragility index, and why to avoid using it to evaluate results
link.springer.com shows its articles on its own site.
Read the article on link.springer.com ↗Article · Jul 2022 · 1 min read
In brief
In brief
Analysis of 87 pediatric surgical trials reveals that fragility indices are strongly correlated with p-values and unfairly penalize small studies common in pediatric surgery. The authors argue fragility index should be avoided as a metric for evaluating trial robustness due to its inherent limitations and bias against smaller but clinically relevant studies.
Written by the GCMD Library team from the article.
Abstract
Background
The fragility index has been gaining ground in the evaluation of comparative clinical studies. Many scientists evaluated trials in their fields and deemed them to be fragile, although there is no consensus on the definition of fragility. We aimed to calculate the fragility index and its permutations for paediatric surgical trials.
Methods
We searched pubmed for prospectively conducted paediatric surgical trials with intervention and control group without limitations and calculated their (reverse) fragility indices and respective quotients along with posthoc-power. Relationships between variables were evaluated using Spearman’s ρ. We also calculated S values by negative log transformation base-2 of P values.
Results
Of 516 retrieved records, we included 87. The median fragility index was 1.5 (interquartile range: 0–4) and the median reverse fragility index was 3 (interquartile range: 2–4), although they were statistically not different (Mood’s test: χ2 = 0.557, df = 1, P = 0.4556). P values and fragility indices were strongly inversely correlated (ρ = − 0.71, 95% confidence interval: − 0.53 to − 0.85, P < 0.0001), while reverse fragility indices were moderately correlated to P values (ρ = 0.5, 95% confidence interval: 0.37–0.62, P < 0.0001). A fragility index of 1 resulted from P values between 0.039 and 0.003, which resulted in S values between 4 and 8.
Conclusions
Fragility indices, reverse fragility indices, and their respective fragility quotients of paediatric surgical trials are low. The fragility index can be viewed as no more than a transformed P value with even more substantial limitations. Its inherent penalisation of small studies irrespective of their clinical relevance is particularly harmful for paediatric surgery. Consequently, the fragility index should be avoided.