Incorrectly analysing stratified and minimised trials may lead to wrongfully rejecting superiority of interventions

It is with great interest that we read the report of Yoshida et al on the effect of second-generation narrow band imaging compared to white light imaging on detecting early gastric cancer in high-risk patients. The trial was expertly designed with a large patient population and, although superiority of narrow band imaging could not be proven, has important implications for further research on this topic. However, a significant issue concerning the analyses attracted our interest and we would like to comment on it. [...]