Table 2. Risk factors for anastomotic leakage - univariate analysis.

	n	anastomotic leakage n (%)	no anastomotic leakage n (%)	p
male	10 477	1 524 (14.5%)	8 953 (85.5%)	<0.0001
female	7 350	603 (8.2%)	6 747 (91.8%)
age ≤68 years	9 592	1 170 (12.2%)	8 422 (87.8%)	0.261
age >68 years	8 266	963 (11.7%)	7 303 (88.3%)
BMI ≤25 kg/m2	8 513	1 010 (11.9%)	7 503 (88.1%)	0.945
BMI >25 kg/m2	8 707	1 036 (11.9%)	7 671 (88.1%)
ASA I and II	11 733	1 314 (11.2%)	10 419 (88.8%)	<0.0001
ASA III and IV	6 107	818 (13.4%)	5 289 (86.6%)
smoking yes	954	165 (17.3%)	789 (82.7%)	<0.0001
smoking no	16 804	1 953 (11.6%)	14 851 (88.4%)
alcohol yes	347	74 (21.3%)	273 (78.7%)	<0.0001
alcohol no	17 411	2 044 (11.7%)	15 367 (88.3%)
diabetes mellitus yes	1 114	140 (12.6%)	974 (87.4%)	0.496
diabetes mellitus no	16 644	1 978 (11.9%)	14 666 (88.1%)
hospital volume < 14ppy	4 632	541 (11.7%)	4 091 (88.3%)	0.314
hospital volume 15–24 ppy	4 737	543 (11.5%)	4 194 (88.5%)
hospital volume 25–36 ppy	4 213	544 (12.1%)	3 669 (87.9%)
hospital volume > 36 ppy	3 985	506 (12.7%)	3 479 (87.3%)
stapled anastomosis	16 612	1 983 (11.9%)	14 629 (88.1%)	0.721
hand sutured anastomosis	1 046	121 (11.6%)	925 (88.4%)
blood transfusion yes	228	39 (17.1%)	189 (82.9%)	0.016
blood transfusion no	17 639	2 095 (11.9%)	15 544 (88.1%)
ileostomy yes	7 148	893 (12.5%)	6 255 (87.5%)	0.003
ileostomy no	5 057	724 (14.3%)	4 333 (85.7%)
UICC I	6 457	721 (11.2%)	5 736 (88.8%)	0.004
UICC II	5 162	600 (11.6%)	4 562 (88.4%)
UICC III	6 248	813 (13.0%)	5 435 (87.0%)
tumour heigth < 6 cm	1 703	256 (15.0%)	1 447 (85.0%)	<0.0001
tumour heigth 6–12 cm	11 144	1 421 (12.8%)	9 723 (87.2%)
tumour heigth > 12 cm	4 501	400 (8.9%)	4 101 (91.1%)

p for Chi-square test, ASA - classification of the American Society of Anaesthesiologists, ppy - patients per year