Table 2.
Baseline characteristics and risk factors of patients who underwent a primary colorectal surgery
| No SSI (n = 1013) | Superficial SSI (n = 46) | Deep SSI (n = 52) | |
|---|---|---|---|
| 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) | |
SSI, surgical site infection; n, number; SD, standard deviation; BMI, body mass index; ASA, American Society of Anaesthesiologists Physical Status; IQR, Interquartile range; ICU, Intensive Care Unit; NA, not applicable
aNot available for hospital F
bNot available for hospital D, E and G, so percentage was calculated without these hospitals
cNot available for hospital F, so percentage was calculated without this hospital
dNot available for hospital E and G, so percentage was calculated excluding these hospitals
eNot available for hospital D, E and G, so percentage was calculated excluding these hospitals
fPercentage was calculated relative to the total number of cultured microorganisms