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Appendix 2 Univariate analysis of factors associated with development of SSI

From: Optimal timing of surgical antimicrobial prophylaxis in laparoscopic surgery: a before-after study

Variables No SSI n = 1207 SSI n = 190 P value
Age, median, (IQR) years 66 (52–75) 70 (60–77) 0.001
  < 65, n (%) 554 (45.9) 71 (37.4) 0.028
  ≥ 65, n (%) 653 (54.1) 119 (62.6)  
Male gender, n (%) 532 (44.1) 74 (39.0) 0.19
Co-morbidities, n (%)
 Diabetes mellitus 164 (13.6) 28 (14.7) 0.67
 Chronic lung diseases 57 (4.7) 12 (6.3) 0.35
 Cardiovascular diseases 59 (4.9) 10 (5.3) 0.83
 Hypertension 442 (36.6) 71 (37.4) 0.84
 Dyslipidemia 198 (16.4) 33 (17.4) 0.74
Current smoker, n (%) 560 (46.4) 110 (47.9) 0.003
ASA score, n (%)
 1 no disturbance 250 (20.7) 29 (15.3) Ref.
 2 mild disturbance 854 (70.8) 144 (75.8) 0.08
 3 severe disturbance 99 (8.2) 17 (9.0) 0.23
 4 life-threatening 4 (0.3) 0 (0) N/A
Wound class, n (%)
 2 clean-contaminated 1202 (99.6) 188 (99.0) 0.25
 3 contaminated 5 (0.4) 2 (1.1) 0.25
Emergent surgery, n (%) 200 (16.6) 22 (11.6) 0.080
Type of surgery, n (%)
 Cholecystectomy 291 (24.1) 16 (8.4) Ref.
 Gastrectomy 294 (24.4) 77 (40.5) < 0.001
 Appendectomy 140 (11.6) 17 (9.0) 0.029
 Colectomy 175 (14.5) 25 (13.2) 0.004
 Proctectomy 306 (25.4) 55 (29.0) < 0.001
 Cholecystectomy and appendectomy 1 (0.1) 0 (0) N/A
Operation time, median, (IQR) min 205 (131–285) 273 (197–337) < 0.001
  < 180, n (%) 502 (41.6) 42 (22.1)  
  ≥ 180, n (%) 705 (58.4) 148 (77.9) < 0.001
SAP drip infusion time, median, (IQR) min 18 (14–23) 18 (14–24) 0.97
Time from SAP completion to surgical incision, median, (IQR) min 12 (4–25) 15 (3–31) 0.37
 31–60 min 175 (14.5) 42 (22.2) Ref.
  < 0 min 143 (11.9) 23 (12.2) 0.16
 0–30 min 861 (71.4) 119 (63.0) 0.005
  > 60 min 26 (2.2) 6 (3.2) 0.52
Intervention status, “yes” 395 (32.7) 60 (31.6) 0.75
  1. NOTE. SSI surgical site infection, IQR interquartile range, ASA American Society of Anesthesiologists, SAP surgical antimicrobial prophylaxis, N/A not applicable