Table 2 Baseline characteristics and risk factors of patients who underwent a primary colorectal surgery

Sex (n, (%))

Male

506 (50.0)

29 (63.0)

31 (59.6)

Female

507 (50.0)

17 (37.0)

21 (40.4)

Age in years (mean, (SD))

65.7 (13.7)

61.8 (15.0)

63.2 (15.4)

Pre-operative risk factors

BMI (mean, (SD))

26.1 (4.6)

27.0 (4.8)

27.6 (7.0)

Missing (n, (%))

29 (2.9)

2 (4.3)

2 (3.8)

ASA grade (n, (%))

Grade I

94 (9.3)

5 (10.9)

3 (5.8)

Grade II

542 (53.5)

20 (43.5)

24 (46.2)

Grade III

289 (28.5)

12 (26.1)

17 (32.7)

Grade IV

43 (4.2)

5 (10.9)

2 (3.8)

Grade V

7 (0.7)

-

-

Missing (n, (%))

38 (3.8)

4 (8.6)

6 (11.5)

Procedure-related risk factors

Type of surgery (n, (%))

 Right hemicolectomy, closed procedure

285 (28.1)

9 (19.6)

6 (11.5)

 Right hemicolectomy, open procedure

129 (12.7)

6 (13.0)

10 (19.3)

 Left hemicolectomy, closed procedure

72 (7.1)

1 (2.2)

5 (9.6)

 Left hemicolectomy, open procedure

33 (3.3)

3 (6.5)

4 (7.7)

 Sigmoid colectomy closed procedure

171 (16.9)

2 (4.3)

5 (9.6)

 Sigmoid colectomy open procedure

108 (10.7)

17 (37.0)

9 (17.3)

 Low anterior colectomy, closed procedure

168 (16.6)

4 (8.7)

12 (23.1)

 Low anterior colectomy, open procedure

47 (4.6)

4 (8.7)

1 (1.9)

Surgical approach (n, (%))

Closed

696 (68.7)

16 (34.8)

28 (53.8)

Open

317 (31.3)

30 (65.2)

24 (46.2)

Duration of surgery in minutes (median, (IQR))^a

132 (68)

143 (64)

137 (56)

Missing (n, (%))

11 (1.1)

-

-

Emergency (n, (%))^b

Yes

124 (18.8)

13 (48.1)

12 (40.0)

No

528 (80.1)

14 (51.9)

18 (60.0)

Missing (n, (%))

7 (1.1)

-

-

Wound class (n, (%))^c

Clean-contaminated (class 2)

724 (81.0)

20 (58.8)

26 (63.4)

Contaminated (class 3)

104 (11.6)

2 (5.9)

7 (17.1)

Dirty-infected (class 4)

65 (7.3)

11 (32.4)

8 (19.5)

Missing (n, (%))

1 (0.1)

1 (2.9)

-

Malignancy (n, (%))

Yes

695 (68.6)

24 (52.2)

33 (63.5)

No

243 (24.0)

20 (43.5)

16 (30.8)

Missing (n, (%))

75 (7.4)

2 (4.3)

3 (5.8)

Stoma (n, (%))

Yes

233 (23.0)

28 (60.9)

22 (42.3)

No

780 (77.0)

18 (39.1)

30 (57.7)

Post-operative risk factors

30-day mortality (n, (%)) ^d

 Yes

28 (3.8)

1 (3.2)

4 (10.5)

 No

703 (96.2)

30 (96.8)

34 (89.5)

ICU admission (n, (%)) ^e

 Yes

162 (24.6)

11 (40.7)

16 (53.3)

 No

497 (75.4)

16 (59.3)

14 (46.7)

Microbiology

Microorganism (n,(%))

 No microorganism identified or no culture taken

NA

28 (60.9)

15 (28.8)

 Positive culture ^f

NA

18 (39.1)

37 (71.2)

  Escherichia coli

6 (25.0)

20 (31.3)

  Enterococcus faecalis

2 (8.3)

7 (10.9)

  Enterococcus faecium

3 (12.5)

6 (9.3)

  Pseudomonas aeruginosa

5 (20.8)

6 (9.3)

  Klebsiella pneumonia

1 (4.2)

4 (6.3)

  Staphylococcus aureus

2 (8.3)

0 (0.0)

  Other

5 (20.9)

21 (32.9)