The examination and treatment of proximal humerus fractures are frequently guided by evidence from randomized controlled trials (RCTs). However, the strength of an RCT must be evaluated by Researchers in this process. The fragility index (FI) is a method used with statistically significant, dichotomous outcomes to assess the number of patients who would change an outcome measure from significant (P<.05) to nonsignificant if the patient outcome changed. They also wanted to see if the FI could be linked to other research strength indicators. A systematic review was conducted using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria to analyze RCTs’ management of proximal humerus fractures. From the beginning of the database to May 2021, PubMed, Ovid MEDLINE, Web of Science, and Embase were searched. The study includes randomized controlled trials with at least one statistically significant (P<.05). Fisher’s exact test was used to compute the FI for each included trial. The journal impact factor and study sample size were associated with FI.

Ten RCTs with a total of 656 patients that were published between 2011 and 2020 were included in the study. The average number of patients in the sample was 67 (mean: 65.6; range: 40-86). The most frequently reported dichotomous statistically meaningful outcome was complications. The median fragility index was 1 (mean: 2.6; range: 0-18), with four studies having a zero fragility score. A median FI of 1 suggests that one patient who had a different result or was not lost to follow-up could have influenced the trial’s relevant conclusions for that outcome. In 50% of the trials, the median number of patients lost to follow-up was 3 (mean: 4.9; range: 0-16). There was no link between FI and sample size (Spearman coefficient, 0.0592; P=.865) or FI and journal impact factor (Spearman coefficient, -0.0229; P=.522). Only 1 or 2 patients suffering a different result or being lost to follow-up would affect the conclusions for the dichotomous outcome evaluated in most research on proximal humerus fractures. Although investigators cannot use the FI to evaluate continuous variables, which are frequently the primary outcome variable in RCTs, it does provide surgeons with another specific measure of study strength to consider when reviewing RCTs.