The fragility index may not be ideal for paediatric surgical conditions: the example of foetal endoscopic tracheal occlusion

Schröder, Arne; Muensterer, Oliver J.; Sochaczewski, Christina Oetzmann von

doi:10.1007/s00383-021-04926-x

Cited by 2 publications

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References 17 publications

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“…The relative risk of 0.11 in the treatment group is much more relevant than the relative risk of 0.8 in the larger trial, but the fragility index favours the larger trial [ 52 ]. The graphical depiction using consonance curves [ 32 ] emphasises this: the relative risk of the smaller trial is farther from the null and thus represents a stronger effect compared to a larger trial with the same P value [ 53 ].…”

Section: Discussionmentioning

confidence: 99%

“…It has been specifically discussed for paediatric surgery using the example of the highly effective foetal endoscopic tracheal occlusion for isolated congenital diaphragmatic hernia, which reports a massive clinical difference of a ten-fold risk of death in the control group with conventional treatment [ 53 ]. Nevertheless, this study could be determined fragile based on its fragility index of 3, which is caused by the small sample size that penalises the large clinical effect.…”

Section: Discussionmentioning

confidence: 99%

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Paediatric surgical trials, their fragility index, and why to avoid using it to evaluate results

2022

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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.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%