Abstract
Fragility index (FI) is a metric used to interpret the results of randomized controlled
trials (RCTs), and describes the number of subjects that would need to be switched
from event to non-event for a result to no longer be significant. Studies that analyze
FI of RCTs in various orthopedic subspecialties have shown the RCTs to be largely
underpowered and highly fragile. However, FI has not been assessed in foot and ankle
RCTs. The MEDLINE and Embase online databases were searched from 1/1/2011 through
11/19/2021 for RCTs involving foot and ankle conditions. FI, fragility quotient (FQ),
and difference between the FI and number of subjects lost to follow-up was calculated.
Spearman correlation was performed to determine the relationship between sample size
and FI. Overall, 1262 studies were identified of which 18 were included in the final
analysis. The median sample size was 65 (interquartile range [IQR] 57-95.5), the median
FI was 2 (IQR 1-2.5), and the median FQ was 0.026 (IQR 0.012-0.033). Ten of 15 (67%)
studies with non-zero FI values had FI values less than the number of subjects lost
to follow-up. There was linear association between FI and sample size (R2 = 0.495, p-value: .031). This study demonstrates that RCTs in the field of foot and ankle surgery
are highly fragile, similar to other orthopedic subspecialties.
Level of Clinical Evidence
Keywords
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Article info
Publication history
Published online: September 08, 2022
Footnotes
Financial Disclosure: This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
Conflict of Interest: None reported.
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© 2022 by the American College of Foot and Ankle Surgeons. All rights reserved.
