Table 3 Crude and adjusted odds ratios (and 95% confidence intervals) from logistic regression evaluating associations between selected characteristics and post-appendectomy surgical site infection

Sex

 Male

1.00

–

 Female

0.71 (0.44, 1.16)

–

Age, for each additional year of age

0.95 (0.8, 1.01)

0.94 (0.88, 1.00)

ASA classification

 Class 1 or 2

1.00

1.00

 Class 3, 4 or 5

3.71 (0.84, 16.41)

4.39 (0.99, 19.49)

Hospital size

 ≤ 200 beds

1.00

–

 200–499 beds

1.27 (0.65, 2.50)

–

 ≥ 500 beds

1.44 (0.74, 2.77)

–

Type of surgical approach

Open

1.00

–

Laparoscopic

0.6 (0.24, 1.51)

–

Duration of surgery, for each additional 30 min

1.15 (1.00, 1.33)

1.22 (1.02, 1.46)

Duration of surgery > 75th centile

1.31 (0.80, 2.12)

–

Perioperative antibiotic regimen

 Amoxicillin/clavulanic acid

1.00

1.00

 Cefuroxime plus metronidazole

0.37 (0.21, 0.65)

0.34 (0.19, 0.60)

Timing of administration of first prophylaxis prior to incision, for each additional 30 min

1.12 (1.03, 1.21)

1.11 (1.02, 1.20)