Applying the fragility index to randomized controlled trials evaluating total neoadjuvant therapy for rectal cancer: A methodological survey

BACKGROUND: Recently, there has been significant interest in, and adoption of, total neoadjuvant therapy (TNT) for locally advanced rectal cancer (LARC). We designed the present study to assess the robustness of the randomized controlled trials (RCTs) evaluating contemporary TNTs for LARC using the fragility index (FI). MATERIALS AND METHODS: Relevant articles were identified through a review article by Johnson et al. in the Canadian Journal of Surgery. Dichotomous outcomes within these RCTs were eligible for inclusion if the reported effect size had a p-value < 0.05. The main outcome was FI for each included outcome. Walsh et al.'s method of calculating FI was utilized. Correlations between FI and research characteristics were assessed using the Spearman's rank correlation coefficients. Risk of bias was assessed using Cochrane recommended tools. RESULTS: Ten RCTs were identified with 25 outcomes having statistically significant differences between groups. Eleven outcomes were time-to-event outcomes, while the remainder were dichotomous outcomes. Approximately half (n = 13) were oncologic outcomes. The median FI was 2 (interquartile range [IQR] 1-16). The number of patients lost to follow-up exceeded the FI in 17 outcomes (68.0 %) and thus these results were considered "fragile". Lower FI was associated with high risk of bias (rho = -0.5594) and greater loss to follow-up (rho = -0.4394), while higher FI was associated with large study size (rho = 0.5120). CONCLUSIONS: The robustness of outcomes from trials assessing TNT for LARC was found to be questionable. Most outcomes were fragile, as determined by the FI. This survey is limited by the number of included studies.