Surgical clinical trials with non-inferiority design: a cross-sectional bibliometric analysis

Background Wide-spread concerns have been raised about possible bias in published surgical non-inferiority trials. Therefore, we performed a comprehensive bibliometric analysis to identify the existence of bias, and provided recommendations for future non-inferiority trials. Methods Databases including MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials were systematically searched (last update on 27 April 2020) to include published phase II and phase III non-inferiority surgical trials. We collected general information and parameters associated with trial design. The association between extracted factors and establishment of non-inferiority was then analyzed. Results A total of 347 trials were included in this study. Only 13 (3.7%) trials reported the pre-specified non-inferiority margin in registration, and 99 (28.5%) trials justified margin selection in ultimate trial publications. A significant association was found between industry funding and increased odds of achieving non-inferiority [odds ratio (OR): 1.17, 95% confidence interval (CI): 1.06 to 1.30, P=0.001]. Moreover, trials which had been presented in conferences were less likely to claim non-inferiority (OR: 0.83, 95% CI: 0.69 to 0.99, P=0.035). Conclusions Our study was the first quantitative analysis revealing the presence of biases in findings of existing surgical non-inferiority trials, which could possibly mislead surgeons' clinical decision making. We suggest improving reporting of detailed study design especially funding sources as well as margin justification for future trials. We also encourage conference presentation of ongoing trials prior to the ultimate publication.