The fragility of statistical findings in distal biceps tendon repairs: a systematic review of randomized controlled trials

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Journal of Shoulder and Elbow Surgery


Background: The purpose of this present study was to perform a fragility analysis to assess the robustness of randomized controlled trials (RCTs) evaluating the distal biceps tendon repairs. We hypothesize that the dichotomous outcomes will be statistically fragile, and higher fragility will exist among statistically significant outcomes comparable to other orthopedic specialties. Methods: Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), randomized controlled trials from 4 orthopedic journals indexed on PubMed from 2000 to 2022 reporting dichotomous measures relating to distal biceps tendon repairs were included. The fragility index (FI) of each outcome was calculated through the reversal of a single outcome event until significance was reversed. The fragility quotient (FQ) was calculated by dividing each fragility index by study sample size. The interquartile range (IQR) was also calculated for the FI and FQ. Results: Of the 1038 articles screened, 7 RCTs containing 24 dichotomous outcomes were included for analysis. The fragility index and fragility quotient of all outcomes was 6.5 (IQR 4-9) and 0.077 (IQR 0.031-0.123), respectively. However, statistically significant outcomes had a fragility index and fragility quotient of 2 (IQR 2-7) and 0.036 (IQR 0.025-0.091), respectively. The average number of patients lost to follow-up was 2.7 patients, with 28.6% of the included studies reporting loss to follow-up (LTF) greater than or equal to 6.5. Conclusions: The literature surrounding distal biceps tendon repair may not be as stable as previously thought and presents a similar fragility index to other orthopedic subspecialties. We therefore recommend triple reporting the P value, fragility index, and fragility quotient to aid in the interpretation of clinical findings reported in biceps tendon repair literature.

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