Table 2 Perioperative characteristics of included patients
Variables | Total (n = 1046) | Non-SSI group (n = 972) | SSI group (n = 74) | p value |
|---|---|---|---|---|
Type of surgery (%) | Â | Â | Â | 0.002 |
 Colon surgery | 641 (61.3%) | 583 (60.0%) | 58 (78.4%) |  |
 Rectal surgery | 405 (38.7%) | 389 (40.0%) | 16 (21.6%) |  |
Urgency of surgery (%) |  |  |  | < 0.001 |
 Elective | 978 (93.5%) | 922 (94.9%) | 56 (75.7%) |  |
 Emergency | 68 (6.5%) | 50 (5.1%) | 18 (24.3%) |  |
ASA score (%) | Â | Â | Â | 0.001 |
 1 or 2 | 818 (78.2%) | 772 (79.4%) | 46 (62.2%) |  |
 3 or 4 | 228 (21.8%) | 200 (20.6%) | 28 (37.8%) |  |
Surgical wound class (%) |  |  |  | < 0.001 |
 Clean-contaminated | 992 (94.9%) | 932 (95.9%) | 60 (81.1%) |  |
 Contaminated or dirty | 54 (5.2%) | 40 (4.1%) | 14 (18.9%) |  |
Timing of hair removal (%) | Â | Â | Â | 0.028 |
 None | 188 (18.0%) | 167 (17.2%) | 21 (28.4%) |  |
 Night before surgery | 672 (64.2%) | 634 (65.2%) | 38 (51.4%) |  |
 Day of surgery | 186 (17.8%) | 171 (17.6%) | 15 (20.3%) |  |
Hair removal | Â | Â | Â | 0.016 |
 No | 188 (18.0%) | 167 (17.2%) | 21 (28.4%) |  |
 Yes | 858 (82.0%) | 805 (82.8%) | 53 (71.6%) |  |
Bowel preparation (%) |  |  |  | < 0.001 |
 None | 331 (31.6%) | 294 (30.2%) | 37 (50.0%) |  |
 MBP only | 575 (55.0%) | 549 (56.5%) | 26 (35.1%) |  |
 OABP only | 42 (4.0%) | 36 (3.7%) | 6 (8.1%) |  |
 MBP + OABP | 98 (9.4%) | 93 (9.6%) | 5 (6.8%) |  |
Hand preparation (%) | Â | Â | Â | 0.209 |
 Disinfectant | 831 (79.4%) | 768 (79.0%) | 63 (85.1%) |  |
 Scrubbing | 215 (20.6%) | 204 (21.0%) | 11 (14.9%) |  |
Approach (%) |  |  |  | < 0.001 |
 Open | 391 (37.4%) | 341 (35.1%) | 50 (67.6%) |  |
 Laparoscopic or robotic | 655 (62.6%) | 631 (64.9%) | 24 (32.4%) |  |
Incisional protection (%) | Â | Â | Â | 0.151 |
 None | 211 (20.2%) | 191 (19.7%) | 20 (27.0%) |  |
 Gauze | 121 (11.6%) | 113 (11.6%) | 8 (10.8%) |  |
 Adhesive incise drapes | 340 (32.5%) | 324 (33.3%) | 16 (21.6%) |  |
 Wound edge protector | 374 (35.8%) | 344 (35.4%) | 30 (40.5%) |  |
Skin closure materials (%) | Â | Â | Â | 0.027 |
 Silk sutures | 627 (60.0%) | 579(59.6%) | 48(64.9%) |  |
 Absorbable sutures | 264 (25.2%) | 253(26.0%) | 11(14.9%) |  |
 Skin staples | 120 (11.5%) | 111(11.4%) | 9(12.2%) |  |
 other | 35 (3.3%) | 29(3.0%) | 6(8.1%) |  |
Fascial or muscle suture materials (%) | Â | Â | Â | 0.545 |
 Silk sutures | 153 (14.6%) | 140 (14.4%) | 13 (17.6%) |  |
 Absorbable sutures | 408 (39.0%) | 377 (38.8%) | 31 (41.9%) |  |
 antimicrobial-coated and absorbable sutures | 485 (46.4%) | 455 (46.8%) | 30 (40.5%) |  |
Incisional wound irrigation (%) | Â | Â | Â | 0.037 |
 None | 81 (7.7%) | 72 (7.4%) | 9 (12.2%) |  |
 Povidone-iodine solution | 182 (17.4%) | 172 (17.7%) | 10 (13.5%) |  |
 Hydrogen peroxide solution | 51 (4.9%) | 48 (4.9%) | 3 (4.1%) |  |
 Saline | 701 (67.0%) | 655 (67.4%) | 46 (62.2%) |  |
 Other | 31 (3.0%) | 25 (2.6%) | 6 (8.1%) |  |
Colostomy/ileostomy |  |  |  | < 0.001 |
 No | 920 (88.0%) | 869 (89.4%) | 51 (68.9%) |  |
 Yes | 126 (12.0%) | 103 (10.6%) | 23 (31.1%) |  |
Grade of lead surgeon (%) | Â | Â | Â | 0.068 |
 Senior | 694 (66.3%) | 651 (67.0%) | 43 (58.1%) |  |
 Middle | 304 (29.1%) | 280 (28.8%) | 24 (32.4%) |  |
 Junior | 48 (4.6%) | 41 (4.2%) | 7 (9.5%) |  |
Surgical duration, min, median (IQR) | 180.0 (130.0–225.0) | 180.0 (130.0–220.0) | 193.5 (143.8–254.3) | 0.019 |
NNIS risk index |  |  |  | < 0.001 |
 0 or 1 | 969 (92.6%) | 916 (94.2%) | 53 (71.6%) |  |
 2 or 3 | 77 (7.4%) | 56 (5.8%) | 21 (28.4%) |  |