Intraoperative hypotension and postoperative delirium: no confusion on confounding

Editor—We would like to thank Zhang and colleagues for their interest in our study. The authors raise concerns about the possibility of residual confounding in our study on the relation between intraoperative hypotension (IOH) and delirium after on-pump cardiac surgery.1Wesselink EM Kappen TH van Klei WA Dieleman JM van Dijk D Slooter AJ Intraoperative hypotension and delirium after on-pump cardiac surgery.Br J Anaesth. 2015; 115:...