The Fragility Index of randomized controlled trials in pediatric anesthesiology

PurposeThe P value is a widely used measure of statistical importance but has many drawbacks and limitations, one being that it does not reflect the robustness of the results of a clinical trial. The Fragility Index (FI) was developed as a measure of how many outcome events would need to change to nonevents to render a significant P value nonsignificant (P >= 0.05). The FI of trials from other medical specialties is typically < 5. We aimed to determine the FI of pediatric anesthesiology randomized controlled trials (RCT) and to test for association with various characteristics of the included trials.MethodsWe conducted a comprehensive systematic search of high-impact anesthesia, surgical, and medical journals from the last 25 years for trials comparing an intervention between two groups with a statistically significant P value (< 0.05) for a dichotomous outcome. We also compared FI values for variables that reflect the quality and importance of a trial.ResultsThe median [interquartile range] FI was 3 [1-7] and correlated positively with the number of participants (r(S) = 0.41; P < 0.001) and events (r(S) = 0.42; P < 0.001), and negatively with the P value (r(PB) = -0.36; P < 0.001). Other measures of trial quality and impact or importance were not strongly associated with the FI.ConclusionsThe FI of published trials in pediatric anesthesiology is similarly low as in other medical specialties. Larger trials with more events and P values <= 0.01 were associated with a higher FI.