The Fragility Index of Hip Arthroscopy Randomized Controlled Trials: A Systematic Survey


Purpose: To characterize the fragility index (FI) of statistically significant results from randomized controlled trials (RCTs) in hip arthroscopy.

Methods: The PubMed-MEDLINE, Embase, and Cochrane databases were queried for hip arthroscopy RCTs published between January 2010 and July 2020. RCTs were included if they contained only 2 treatment arms, randomized patients to a 1:1 allocation to each arm, and reported at least 1 statistically significant dichotomous outcome. The fragility quotient was calculated for each RCT by dividing the FI by the sample size. Smaller FIs indicated more fragile results. Risk of bias was assessed using the Cochrane risk-of-bias tool for randomized trials.

Results: We identified 8 hip arthroscopy RCTs that met all inclusion and exclusion criteria. Most of the studies were assessed to have an overall low risk of bias. In the 2 studies with a moderate risk of bias and 1 study with a high risk of bias, concerns were raised about high rates of crossover and loss to follow-up. The median FI was 4, with FIs ranging from 0 to 14, but half of the studies had an FI of 2 or less. In 4 of the 8 studies, the number of patients lost to follow-up was greater than the FI.

Conclusions: A systematic survey of hip arthroscopy RCTs resulted in a low FI, indicating that the findings tended to be fragile. A low FI was consistent with findings reported in other orthopaedic and medical literature. Given these results, there is a possibility for findings to be altered by factors such as loss to follow-up, measurement subjectivity, crossover, and biased study design. Results on the fragility of hip arthroscopy RCTs were similar to those reported in general or orthopaedic-specific literature.

Level of evidence: Level II, systematic review of Level I and II studies.

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