Is a self-expandable metal stent better than a plastic stent in unresectable complex hilar cholangiocarcinoma with regard to the adequacy of drainage and survival of the patients?

摘要

We read with great interest the recent article by Sangchan et al.1 The authors concluded that endoscopic biliary drainage with a self-expandable metal stent (SEMS) provides better adequacy of drainage and longer survival compared with the plastic stent (PS) in patients with unresectable complex hilar cholangiocarcinoma. It is an interesting study. Nevertheless, several issues seem worthy of comment.First, as noted in this article, the difference in patient age distribution between the SEMS and PS groups was statistically significant (P = .013). It leads to an imbalance between treatment groups. However, ignoring the imbalances in continuous covariates causes the loss of power in randomized, controlled trials. Moreover, an extreme degree of imbalance in baseline variables prognostic of response variables may lead to a misleadingly significant estimate of treatment effect. It is suggested that covariate adaptive allocation is often adopted in clinical trials to maintain the balance of baseline covariates.3