Fragility Index: How robust are your results ?

Many orthopedic trials rely on dichotomous outcomes, but a p-value alone doesn’t tell the whole story about how stable those findings really are. The fragility index offers a simple way to gauge that stability by asking how many patients would need to switch from “no event” to “event” before a statistically significant result disappears. When that number is small, the result is fragile and should be interpreted cautiously—especially if more patients were lost to follow-up than the fragility index itself. Examples from tibial fracture research show how quickly significance can vanish with only a few outcome changes. Across orthopedics, reviews consistently reveal low fragility indices, often between 1 and 3, highlighting how vulnerable many RCT conclusions are and underscoring the need for larger, more robust trials.