Table 4.

Risk factors for in-hospital and postdischarge surgical site infection (SSI).

	In-hospital period			Post-discharge period
Variable	Total §	No. SSI/total§	Odds Ratio (95% CI^^)	Total§S	No. SSI/total §§	Odds Ratio (95% CI^^)
Gender
Male	4,665	67/1,625	1.57 (1.12–2.21)*	4,258	30/1,454	0.92 (0.58–1.45)#
Female		81/3,040			63/2,804
Age (years)
18–36		15/1,163	1		20/1,086	1
37–54	4,420	26/1,057	1.93 (0.98–3.84)#	4,027	19/978	1.06 (0.54–2.08)#
55–70		44/1,162	3.01 (1.62–5.69)*		23/1,063	1.18 (0.62–2.25)#
>70		60/1,038	4.70 (2.58–8.68)*		28/900	1.71 (0.93–3.18)#
Emergency Intervention
	4,655			4,258
Yes		51/1,002	1.97 (1.37–2.82)*		18/903	0.89 (0.51–1.53)#
No		97/3,653			75/3,355
NNIS score §
		4/358	1		4/336	1
M		38/2,621	1.30 (0.44–4.32)#		52/2,459	1.79 (0.62–5.87)#
	4,579			4,166
0		65/1,260	4.81 (1.67–		25/1,108	1.92 (0.63–6.54)#
1		30/340	15.63)*		11/263	3.62 (1.05–
2 + 3			11.42 (3.86–38)*			13.65)*
Prosthesis
Yes	4,652	6/801	0.20 (0.08–0.46)*	4,245	17/756	1.03 (0.58–1.80)#
No		142/3,851			76/3,489
Pre-operative hospital stay (days)	4,589			4,196
		72/3,300			58/3,064
0–1		69/1,289	2.54 (1.79–3.60)*		33/1,132	1.56 (0.99–2.45)*
>1
Drains
No		41/3,045	1		56/2,853	1
1–3 days	4,665	19/764	1.87 (1.04–3.33)*	4,261	12/686	0.89 (0.45–1.72)#
>3 days		88/856	8.40 (5.66–12.48)*		23/722	1.64 (0.97–2.75)*
Perioperativ e antibiotic prophylaxis	4,665			4,258
Yes		139/4,071	0.44 (0.21–0.89)*		74/3,718	1.80 (1.04–3.07)*
No		9/594			19/540

§ total number of procedures surveilled during hospital stay not equal to the study cohort (n = 4,665) for missing data.

NNIS = National Nosocomial Infection Surveillance.

§§ total number of interventions surveilled during post-discharge, does not include missing data for SSI occurrence during postdischarge (n = 258), and patients with in-hospital SSI (n = 148) or with postoperative hospital stay ≥ 30 days (n = 25).

^^ 95% confidence intervals.

* p-value < 0.05.

# p value not significant.

M: no risk factor + endoscopical procedure.