The Fragility of Tourniquet Use in Total Knee Arthroplasty: A Systematic Review of Randomized Controlled Trials.

BACKGROUND: Physicians utilize P-values to interpret clinical trial data and guide patient-care decisions. Fragility analysis assesses the stability of statistical findings in relation to outcome event reversals. This study assessed the statistical fragility of recent randomized controlled trials (RCTs) investigating tourniquet use in total knee arthroplasty (TKA). METHODS: We queried PubMed, EMBASE, and MEDLINE for RCTs comparing outcomes in TKA based on tourniquet use. Fragility index (FI) and reverse fragility index (reverse FI) were calculated - for significant and nonsignificant outcomes, respectively - as the number of outcome reversals required to change statistical significance. The fragility quotient (FQ) was calculated by dividing the FI or reverse FI by the sample size. Median overall FI and FQ were calculated for all included outcomes, and sub-analyses were performed by reported significance. The literature search yielded 23 studies reporting 91 total dichotomous outcomes. RESULTS: Overall median FI was 4 with an interquartile range (IQR) of 3 to 6. Overall median FQ was 0.0476 (IQR 0.0291 to 0.0867). A total of 11 outcomes were statistically significant with a median FI and FQ of 2 (IQR 1.5 to 5) and 0.0200 (IQR 0.0148 to 0.0484), respectively. There were 80 outcomes that were nonsignificant with a median reverse FI of 4 (IQR 3 to 6). Loss to follow-up was greater than the median FI in 17.6% of outcomes. CONCLUSION: Altering a small number of outcomes is often sufficient to reverse findings in RCTs evaluating tourniquet use in TKA. We recommend including fragility analyses to increase reliability in the interpretation of study conclusions.