Table 3. Stratification analysis by age, sex and coexisting medical conditions regarding association between preoperative pressure ulcer and postoperative mortality.

		30-day postoperative mortality
	n	Deaths	Mortality, %	RR	(95% CI)*
Sex
Female	15974	227	1.4	1.87	(1.43–2.46)
Male	18808	334	1.8	1.81	(1.44–2.26)
Age, years
20–59	6672	68	1.0	1.62	(0.99–2.63)
60–69	4908	56	1.1	2.29	(1.30–4.06)
70–79	11690	176	1.5	2.32	(1.68–3.20)
≥80	11512	261	2.3	1.56	(1.22–2.00)

CI, confidence interval; RR, rate ratio.

*The rate ratio of postoperative mortality associated with pressure with multivariate adjustment.