N (%)    
Characteristics Cases
N = 87
Controls
N = 174
Unadjusted mOR (CI 95 %) P
Preoperative factors
Age (years), Mean (SD)1
Male gender
Diabetes Mellitus
Underlying Chronic lung diseasse
Acute myocardial infarction
Neoplasm
BMI ≥ 30 kg/m2
Albumin < 3 g/dl
Peripheral vascular disease
Ejection fraction < 30
Chronic Renal Insufficiency
Smoking
NYHA class IV

68 (9.1)
68 (78.2)
57 (65.5)
14 (16.1)
32 (36.8)
7 (8.0)
52 (60.0)
51 (59.3)
9 (10.3)
2 (2.3)
14 (16.1)
28 (32.2)
36 (42.3)

66 (8.7)
138 (79.3)
70 (40.2)
18 (10.3)
46 (27.4)
9 (5.2)
90 (51.7)
111 (64.0)
20 (11.5)
5 (2.9)
17 (9.8)
37 (21.2)
29 (16.7)

1.0 (0.9-1.04)
0.9 (0.5-1.7)
2.8 (1.6-4.8)
1.6 (0.8-3.4)
1.7 (0.9-3.0)
1.7 (0.6-4.9)
1.4 (0.8-2.4)
0.8 (0.4-1.4)
0.8 (0.3-2.1)
0.8 (0.1-4.1)
1.7 (0.8-3.7)
1.8 (1.0-3.4)
4.2 (2.1-8.3)

0.5
0.8
0.0001
0.2
0.07
0.3
0.2
0.5
0.7
0.8
0.1
0.04
0.0001
Intraoperative factors
Double IMA
Other procedure 1
Mean duration of surgery (SD, min)
Mean perfusion time (SD, min)
Surgeon experience
NNIS risk index ≥2

8 (9.2)
8 (9.2)
187.4 (65.2)
73.2 (36.5)
43 (49.4)
28 (32.2)

6 (3.4)
15 (8.6)
161.7 (49.7)
65.4 (28.7)
78 (44.8)
30 (17.2)

2.7 (0.9-7.6)
1.1 (04-2.7)
1.01 (1.0-1.01)
1.01 (1.0-1.01)
1.2 (0.7-1.8)
2.6 (1.3-5.1)

0.07
0.8
0.001
0.04
0.5
0.005
Post-operative factors
Length of stay, Mean (SD, d)2
Central venous catheter, Mean (SD, d)2
Urinary catheter, Mean (SD, d)2
Surgical drainage, Mean (SD, d)2
Mechanical ventilation, Mean (SD, d)2
Other infection
Reexploration
AVC
Transfusion
Dehiscence

29.7 (21.0)
9.9 (13.1)
16.4 (22.3)
9.5 (9.3)
6 (10.8)
27 (31.4)
15 (17.2)
7 (8.0)
46 (53.0)
33 (37.9)

13.4 (9.6)
4.3 (7.0)
6.0 (8.0)
4.6 (3.2)
1.8 (3.1)
19 (33.3)
6 (3.4)
2 (1.1)
68 (39.1)
1 (0.6)

1.1 (1.05-1.1)
1.08 (1.03-1.1)
1.06 (1.03-1.1)
1.3 (1.1-1.4)
1.1 (1.04-1.2)
1.2 (0.5-2.9)
6.8 (2.2-20.6)
12.5 (1.5-103.1)
1.8 (1.05-3.1)
66 (9.0- 482.5)

0.0001
0.01
0.0001
0.0001
0.002
0.6
0.001
0.02
0.03
0.0001
CABG: Coronary artery bypass grafting; SD: standard deviation, mOR: matched Odds Ratio, CI: Confidence Interval, ICU: Intensive Care Unit. NNIS: National Nosocomial Infection Surveillance. BMI: body mass index.
1Common Odds Ratio assuming a linear trend.
2Other procedures include repair of atrioseptal defect and ventriculoseptal defect, removal of atrial myxoma, and graft repair of the ascending aorta.
Table 1: Risk factors for surgical site infection after CABG among 261 patients.