Risk factors and prediction model for inpatient surgical site infection after elective abdominal surgery

Table 1 Univariate analysis of risk factors associated with surgical site infection

Factors		SSI (n = 150)	NSSI (n = 2868)	X2	P value
Gender	Male	85	815	54.356	< 0.001
	Female	65	2053
Age	< 70 yr	83	2145	27.927	< 0.001
	≥ 70 yr	67	723
Marriage	Married	132	2678	10.006	0.007
	Single	7	108
	Others	11	82
Residence	Rural	83	1313	5.232	0.022
	Urban	67	1555
Antibiotic use	Yes	14	66	27.316	< 0.001
	No	136	2802
Hypertension	Yes	20	519	2.204	0.138
	No	130	2349
Diabetes	Yes	46	356	41.137	< 0.001
	No	104	2512
Preoperative duration	< 7 d	108	2248	3.391	0.066
	≥ 7 d	42	620
NRS 2002	< 3	104	2652	44.853	< 0.001
	≥ 3	46	216
NNIS	< 2	80	2420	96.634	< 0.001
	≥ 2	70	448
RBC (1012/L)	< 4	86	1565	0.44	0.507
	≥ 4	64	1303
WBC (109/L)	< 10	86	1943	7.017	0.008
	≥ 10	64	925
HB (g/L)	< 120	67	1473	2.555	0.11
	≥ 120	83	1395
PCT (μg/L)	< 0.05	58	1824	37.748	< 0.001
	≥ 0.05	92	1044
ALB (g/L)	< 35	105	1344	30.574	< 0.001
	≥ 35	45	1524
TG (mmol/L)	< 1.7	124	1503	0.433	0.511
	≥ 1.7	26	365
LDL (mmol/L)	< 3.37	95	1456	9.011	0.003
	≥ 3.37	55	1412
HDL (mmol/L)	< 1.55	79	1722	3.222	0.073
	≥ 1.55	71	1146
TC (mmol/L)	< 6.45	117	2149	0.718	0.397
	≥ 6.45	33	719
Blood loss (mL)	< 200	87	2401	65.118	< 0.001
	≥ 200	63	467
Drainage	Yes	103	1129	50.661	< 0.001
	No	47	1739
Tension suture	Yes	7	72	Fisher	0.112
	No	143	2796
Flushing	Yes	86	1596	0.164	0.685
	No	64	1272
Item	Single	41	1443	30.12	< 0.001
	Multiple	109	1425
Anesthesia	General	133	1969	26.525	< 0.001
	N-general	17	899
Incision	I	8	95	228.143	< 0.001
	II	103	2702
	III	39	71
Season	Spring	36	825	301.157	< 0.001
	Summer	41	68
	Autumn	42	382
	Winter	31	1593
Surgical site	Uterus	22	1252	188.267	< 0.001
	Liver	12	821
	Gastrointestinal	76	501
	Appendix	27	152
	Kidney	5	107
	Groin	8	35

SSI: Surgical site infection; NNIS: National Nosocomial Infections Surveillance; NRS 2002: Nutritional Risk Screening 2002; RBC: Red blood cell; WBC: White blood cell; HB: Hemoglobin; PCT: Procalcitonin; ALB: Albumin; TG: Triglyceride; LDL: Lipoprotein cholesterol; HDL: High-density lipoprotein; TC: Total cholesterol.

Table 2 Multivariate analysis of risk factors associated with surgical site infection

Factors	OR	95%CI		P value
The history of diabetes	5.698	3.305	9.825	0.001
The use of antibiotic	14.977	2.865	78.299	0.001
NRS 2002 ≥ 3	2.426	1.199	4.909	0.014
NNIS ≥ 2	2.362	1.019	5.476	0.045
PCT ≥ 0.05 μg/L	1.687	1.056	2.695	0.029
LDL < 3.37 mmol/L	1.719	1.039	2.842	0.035
General anesthesia	3.334	1.134	9.806	0.029
Blood loss ≥ 200 mL	29.026	13.751	61.266	< 0.001
Surgical site
Uterus	Ref.
Gastrointestinal	3.646	1.097	12.121	0.035
Appendix	23.056	6.944	76.548	< 0.001
Kidney	6.256	1.377	29.361	0.020
Groin	53.589	10.354	277.357	< 0.001
Incision
I	Ref.
III	11.226	1.689	74.630	0.012
Season
Spring	Ref.
Summer	18.948	9.537	37.648	< 0.001
Autumn	2.648	1.454	4.823	0.001
Winter	0.481	0.266	0.872	0.016

PCT: Procalcitonin; LDL: Lipoprotein cholesterol; NNIS: National Nosocomial Infections Surveillance; NRS 2002: Nutritional Risk Screening 2002; OR: Odds ratio; CI: Confidence interval.