8.

Trial sequential analysis of pain (9 to 24 hours) (opioid versus control) 
 The diversity‐adjusted required information size (DARIS) was 25 participants based on a minimal relevant difference (MIRD) of 1 cm on the visual analogue scale, a variance (VAR) of 0.78, an alpha (a) of 5%, a beta (b) of 20%, and a diversity (D²) of 0%. As this was crossed by the first trial, the trial sequential boundaries were not drawn. A post‐hoc analysis with the MIRD revised to 0.25 cm was performed. The conventional statistical boundaries (dotted red line) and trial sequential monitoring boundaries (red line) are crossed by cumulative Z curve (blue line) after the first trial. Although the DARIS has not been reached, the findings are consistent with opioid decreasing pain between 9 and 24 hours compared with inactive control with low risk of random errors.