Table 3.

Multivariate Cox proportional hazards analysis for the risk of postoperative analgesic administration.

	Before PS matching			After PS matching
	HR	95% CI	P value	HR	95% CI	P value
Pre-RSB	0.82	0.63–1.08	.16	0.71	0.53–0.95	.023

The confounding factors were as follows: age (≥65 years), sex, body mass index (more than 30 or not), department (general surgery, urology, and gynecology), receipt of dual antiplatelet therapy before surgery, anticoagulant medication before surgery, emergency, renal replacement therapy, intraoperative analgesics (fentanyl, remifentanil, acetaminophen, flurbiprofen, and tramadol), duration of anesthesia (<120 min, 120–240 min, and ≥ 240 min), type of anesthesia (sevoflurane, desflurane, total intravenous anesthesia, and others), and year (2013, 2014, 2015, 2016, 2017, and 2018).

CI = confidence interval, HR = hazard ratio, pre-RSB = preoperative rectus sheath block, PS = propensity score.