The statistical fragility of the management options for reverse shoulder arthroplasty: a systematic review of randomized control trial with fragility analysis.

Reverse shoulder arthroplasty (RSA) is used in the treatment of traumatic and arthritic pathologies, with expanding clinical indications and as a result there has been an increase in clinical research on the topic. The purpose of this study was to examine the statistical fragility of randomized control trials (RCTs) reporting outcomes from RSA. A systematic search was undertaken to find RCTs investigating RSA. The Fragility Index (FI) was calculated using Fisher's exact test, by sequentially altering the number of events until there was a reversal of significance. The Fragility Quotient (FQ) was calculated by dividing the FI by the trial population. Each trial was assigned an overall FI and FQ calculated as the median result of its reported findings. Overall, 19 RCTs warranted inclusion in the review, representing 1146 patients, of which 41.2% were male, with a mean age of 74.2 ± 4.3 years and mean follow-up of 22.1 ± 9.9 months. The median RCT population was 59, with a median of 9 patients lost to follow-up. The median FI was 4.5, and median FQ was 0.083, indicating more patients did not complete the trial than the number of outcomes which would have to change to reverse the finding of significance. This review found that the RCT evidence for RSA management may be vulnerable to statistical fragility, with a handful of events required to reverse a finding of significance.