Background: Dichotomous outcomes are frequently reported in orthopaedic research and have substantial clinical implications. This study utilizes the fragility index (FI) and fragility quotient (FQ) metrics to determine the statistical stability of outcomes reported in total joint arthroplasty randomized controlled trials (RCTs) relating to periprosthetic joint infection (PJI).
Methods: The RCTs that reported dichotomous data related to PJI published between January 1, 2010, and December 31, 2022, were evaluated. The FI and reverse FI (RFI) were defined as the number of outcome event reversals required to reverse the significance of significant and nonsignificant outcomes, respectively. The FQ was determined by dividing the FI or RFI by the respective sample size. There were 108 RCTs screened, and 17 studies included for analysis.
Results: A total of 58 outcome events were identified, with a median FI of 4 (interquartile range [IQR] 2 to 5) and associated FQ of 0.0417 (IQR 0.0145 to 0.0602). The 13 statistically significant outcomes had a median FI of 1 (IQR 1 to 2) and FQ of 0.00935 (IQR 0.00629 to 0.01410). The 45 nonsignificant outcomes had a median RFI of 4 (IQR 3 to 5) and FQ of 0.05 (IQR 0.0361 to 0.0723). The number of patients lost to follow-up was greater than or equal to the FI in 46.6% of outcomes.
Conclusions: Statistical outcomes in RCTs analyzing PJI are fragile and may lack statistical integrity. We recommend a comprehensive fragility analysis, with the reporting of FI and FQ metrics, to aid in the interpretation of outcomes in the total joint arthroplasty literature.
Keywords: periprosthetic joint infection; randomized controlled trial; statistical fragility; systematic review; total joint arthroplasty.
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