Randomization and blinding methods
Computer-generated randomization was performed by principal investigator at a 1:1 ratio with permuted block design with a block size of four through an online application accessed from the website, “Sealedenvelope.com”. Eligible patients were randomly assigned to either the deep or shallow anesthesia group according to a randomization list. The attending anesthesiologists were informed of the group allocation immediately before anesthesia induction using the sealed opaque envelope technique. The patients and investigators involved in the postoperative follow-up and data analysis were blinded to the group allocation.