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Table 1 Risk factors associated with superficial surgical site infection in complicated appendicitis

From: Clinical prediction score for superficial surgical site infection after appendectomy in adults with complicated appendicitis

Risk factors No SSI SSI P value
Patient-related
Gender, number (%)
 Male 291 (90.9) 29 (9.1) 0.773
 Female 255 (91.7) 23 (8.3)
Age, year, mean (SD) 45.5 (0.78) 44.4 (2.31) 0.674
BMI, kg/m2, mean (SD) 23.3 (0.19) 24.5 (0.48) 0.023
Smoking, number (%)
 Yes 85 (90.4) 9 (9.6) 0.693
 No 460 (91.2) 43 (8.6)
ASA classification, number (%)
 Class I 319 (92.7) 25 (7.3) 0.290
 Class II 151 (88.8) 19 (11.2)
 Class III 65 (90.1) 7 (9.7)
 Class IV 5 (83.3) 1 (16.7)
Diabetes, number (%)
 Yes 40 (78.4) 11 (21.6) 0.001
 No 502 (92.5) 41 (7.5)
Hypertension, number (%)
 Yes 104 (91.2) 10 (8.8) 0.989
 No 439 (91.3) 42 (8.7)
Duration of symptoms, hours, median (IQR) 24 (14, 48) 24 (24, 48) 0.055
Presence of fever (≥ 37.8 °C), number (%)
 Yes 284 (92.2) 24 (7.8) 0.389
 No 258 (90.2) 28 (9.8)
White blood cell count, cell/mm3, mean (SD) 15,563 (4998) 16,658 (4551) 0.130
Hct < 30%, number (%)
 Yes 25 (92.6) 2 (7.4%) 0.821
 No 517 (91.3) 49 (8.7%)
Operative-related
Appendicitis severity classification, number (%)
 Gangrene 141 (97.2) 4 (2.8) 0.004
 Ruptured 405 (89.4) 48 (10.6)
No SSI SSI P value
Wound
 Incisional length, cm, mean (SD) 5.6 (2.24) 6.9 (2.62) < 0.001
 Subcutaneous fat thickness, cm, mean (SD) 3.0 (2.00) 3.7 (2.20) 0.033
 Visible wound contamination, number (%)
  Exudative fluid
   Yes 147 (88.6) 19 (11.6) 0.139
   No 399 (92.4) 33 (7.6)
  Purulent fluid
   Yes 202 (90.2) 22 (9.8) 0.450
   No 344 (92.0) 30 (8.0)
Fecal contamination, number (%)
 Yes 143 (85.1) 25 (14.9) 0.001
 No 378 (93.8) 25 (6.2)
Operative time (minutes), number (%)
 ≤ 75 129 (83.8) 25 (16.2) < 0.001
 > 75 412 (93.9) 27 (6.2)
Used of closed suction drain, number (%)
 Yes 109 (93.2) 8 (6.8) 0.413
 No 433 (90.8) 44 (9.2)
  1. ASA American Society of Anesthesiologists, BMI body mass index, SD standard deviation, SSI superficial surgical site infection