Independent risk factors and a predictive model for surgical site infection following colorectal cancer surgery

Table 1 Comparison of surgical site infection rates by surgical approach

Surgical approach	Total cases	Infection cases	Infection rate (%)	P value
Laparoscopic	104	11	10.58	0.002
Open	124	34	27.42
Total	228	45	19.74

Table 2 Distribution of pathogens in surgical site infections in colorectal cancer patients

Pathogen category	Number of strains (n)	Composition ratio (%)
Gram-negative bacteria	27	56.25
Gram-positive bacteria	17	35.42
Fungi	4	8.33
Total	48	100

Table 3 Comparison of general data between the infection and non-infection groups, n (%)/mean ± SD

	Infection group (n = 45)	Non-infection group (n = 183)	χ2/t	P value
Age (years)	66.55 ± 8.51	61.73 ± 9.03	3.271	0.001
Sex			0.061	0.805
Male	19 (42.22)	81 (44.26)
Female	26 (57.78)	102 (55.74)
BMI (kg/m2)	25.90 ± 3.03	22.01 ± 2.97	7.858	< 0.001
Surgical approach
Open surgery	34 (75.56)	90 (49.18)	10.131	0.002
Laparoscopic surgery	11 (24.44)	93 (50.82)
Comorbid diabetes mellitus			27.391	< 0.001
Yes	22 (48.89)	25 (13.66)
No	23 (51.11)	158 (86.34)
Incision length (cm)	12.26 ± 3.31	9.89 ± 2.86	4.828	< 0.001
Duke stage (stage C/D)			0.349	0.555
Stage C	28 (62.22)	105 (57.38)
Stage D	17 (37.78)	78 (42.62)

Measurement data (age, body mass index, incision length) were compared using independent samples t-test; counting data (sex, surgical approach, diabetes mellitus, duke stage) were compared using χ² test. BMI: Body mass index.

Table 4 Assignment

Factors	Assignment
	0	1
Surgical methods	Laparoscopic surgery	Open surgery
Diabetes mellitus	No	Yes
Infection	No	Yes
Obesity (BMI ≥ 28 kg/m2)	No	Yes

BMI: Body mass index.

Table 5 Multivariate logistic regression analysis of surgical site infection in colorectal cancer patients

Factors	B	SE	Wals	df	Sig.	Exp (B)	95%CI for EXP(B)
							Lower limit	Upper limit
Surgical methods	2.815	0.512	30.226	1	0.000	16.687	6.118	45.514
Diabetes mellitus	0.774	0.477	2.634	1	0.105	2.168	0.851	5.521
Age	0.068	0.026	7.070	1	0.008	1.071	1.018	1.126
Obesity	2.632	0.813	10.488	1	< 0.001	13.895	2.826	68.320
Incision length	0.325	0.080	16.432	1	< 0.001	1.384	1.183	1.619

Table 6 Predictive efficacy of individual predictors and the combined model for surgical site infection

Predictors	Area under the curve	Sensitivity (%)	Specificity (%)	Accuracy (%)
Joint	0.898	77.05	88.89	79.39
Obesity	0.600	97.81	22.22	82.90
Surgical approach	0.772	72.13	82.22	74.12
Incision length	0.704	61.20	73.33	63.6
Age	0.647	53.01	73.33	57.02