Table 1. Univariate multilevel analysis. Variables of patients’ characteristics and presence/absence of AE^* in patients within 30 days post-intervention (N = 1422) Barcelona, Spain 2014-2015.

Patient Variables		Presence of AE*%	Absence of AE*%	p†
Sex	Female	38.0	62.0	0.408
	Male	40.1	59.9
Comorbidity	Yes	43.5	56.6	<0.001†
	No	35.2	64.8
Expertise	General surgery	41.8	58.2	<0.001†
	Traumatology	41.2	58.8
	Gynecology	31.7	68.3
	Thoracic surgery	28.6	71.4
	Vascular surgery	33.3	66.7
	Neurosurgery	52.4	47.6
	Plastic surgery	0	100
Age (years)	Mean (SD)‡	63.5(14.33)	63.3(17.17)	0.900
Stay (hours)	Mean (SD)‡	25.04(3.73)	24.8 (4.0)	0.321

^*AE: Adverse Event,

^†p: p-value significance,

^‡SD: Standard deviation.