Table 3.

Risk factors for surgical site infection (SSI).

			Univariate analysis		Multivariate analysis
Variable	Total §	No. SSI/total§	Odds Ratio (95% CI^^)	p*	Odds Ratio (95% CI^^)	p*
Gender
Male	4,406	97/1521	1.30 (0.99–1.70)	0.054	1.13 (0.83–1.55)	0.429
Female		144/2,885
Age, years
18–36	4,172	35/1,101	1
37–54		45/1,004	1.43 (0.89–2.30)	0.118	1.11 (0.72–1.69)	0.635
55–70		67/1,107	1.96 (1.27–3.04)	0.001	0.91 (0.63–1.31)	0.622
>70		88/960	3.07 (2.02–4.69)	<0.001	1.51 (0.91–2.51)	0.113
Emergency Interventions
Yes	4,396	69/944	1.50 (1.11–2.03)	0.005	1.73 (1.22–2.44)	0.002
No		172/3,452
NNIS score
M	4,330	8/341	1
0		90/2,507	1.55 (0.72–3.48)	0.237	1.18 (0.77–1.82)	0.441
1		90/1,182	3.43 (1.59–7.71)	<0.001	1.82 (1.14–2.90)	0.012
2 + 3		41/300	6.59 (2.91–15.50)	<0.001	3.34 (1.41–7.93)	0.006
Prosthesis
Yes	4,393	23/762	0.60 (0.39–0.91)	0.011	0.62 (0.38–1.04)	0.07
No		218/3,631
Pre-operative hospital stay, days
	4,337	130/3,136	2.15 (1.63–2.83)	<0.001	1.45 (1.06–1.98)	0.02
0–1		102/1,201
>1
Drains
No	4,406	97/2,894	1
1–3 days		31/702	3.04 (2.31–3.99)	<0.001	2.39 (0.65–1.65)	<0.001
>3 days		111/810	4.58 (3.41–6.15)	<0.001	2.17 (1.38–3.43)	<0.001
Perioperative prophylaxis
Yes	4,406	213/3,857	0.92 (0.60–1.40)	0.684	-	-
No		28/549

§ total number of procedures considered not equal to the study cohort (n = 4,665) for missing data; also patients with missing data for SSI occurrence during postdischarge (n = 258) were excluded from the analysis.

^^ 95% confidence intervals (CI).

* p-value.

M no risk factor for NNIS index score + laparoscopical procedure (NNIS = -1).

NNIS = National Nosocomial Infection Surveillance.