5.

Trial sequential analysis of morbidity (open surgery versus endoscopic retrograde cholangio pancreatography (ERCP)) 
 The diversity‐adjusted required information size (DARIS) was calculated to 3,145 patients, based on the proportion of patients in the control group with the outcome of 18.72%, a relative risk reduction of 20%, an alpha of 5%, a beta of 20%, and a diversity of 0%. After accruing a total of 729 participants in eight trials, only 23.18% of the DARIS has been reached. So, the futility area was not drawn. The cumulative Z‐curve (blue line) does not cross the trial sequential monitoring boundaries (red line) or the conventional boundaries (etched red line). This is consistent with absence of current evidence of any significant difference between open surgery and ERCP but significantly increased or decreased morbidity of open surgery compared to ERCP cannot be ruled out.