Subcutaneous fat thickness and abdominal depth are risk factors for surgical site infection after gastric cancer surgery

Table 1 Characteristics of the study group, n (%)

Variable	Surgical site infection		P value
	Absent (n = 315)	Present (n = 40)
Age (yr)	65.3 ± 9. 6	66.4 ± 9.8	0.529
Male	227 (72.10)	28 (70.00)	0.785
BMI (kg/m2)	22.68 ± 3.22	25.12 ± 2.78	< 0.001a
SFT (mm)	14.20 (10.00–18.40)	20.45 (17.00–26.63)	< 0.001a
AD (mm)	64.90 (50.60–78.20)	82.50 (68.43–97.00)	< 0.001a
Smoking	87 (27.60)	15 (37.50)	0.193
Alcohol use	66 (21.00)	11 (27.50)	0.344
Diabetes	40 (12.70)	9 (22.50)	0.090
Laparoscopic-assisted surgery	96 (30.5)	6 (15.00)	0.042a
Hypertension	95 (30.2)	12 (30.0)	0.984
Type of resection			0.371
Total gastrectomy	206 (65.40)	29 (34.60)
Partial gastrectomy	109 (35.98)	11 (27.50)
Operation time (min)	210.00 (180.00–240.00)	240.00 (209.25–270.00)	0.013a
Blood loss (mL)	150.00 (100.00–200.00)	150.00 (112.00–200.00)	0.099
History of laparotomy	47 (14.90)	7 (17.50)	0.669
Albumin (g/dL)	39.37 ± 4.99	40.29 ± 3.55	0.258
Prealbumin (g/dL)	188.25 ± 59.06	194.92 ± 63.09	0.509
TNM stage			0.304
I	96 (29.2)	10 (25.0)
II	92 (30.5)	17 (42.5)
III	127 (40.3)	13 (32.5)

^aP < 0.05.

BMI: Body mass index; SFT: Subcutaneous fat thickness; AD: Abdominal depth; TNM: Tumor-node-metastasis.

Table 2 Risk factors for surgical site infection in univariate and multivariate analysis

Variable	Univariate analysis	P value	Multivariate analysis	P value
	OR (95%CI)		OR (95%CI)
Age (yr)	1.011 (0.977–1.047)	0.528
Male	0.905 (0.440–1.858)	0.785
BMI (kg/m2)	1.259 (1.133–1.398)	< 0.001	-	-
SFT (mm)	1.137 (1.186–1.192)	< 0.001	1.150 (1.090–1.214)	< 0.001a
AD (mm)	1.031 (1.017–1.046)	< 0.001	1.024 (1.009–1.040)	0.002a
Smoking	1.572 (0.792–3.123)	0.196
Alcohol use	1.431 (0.679–3.015)	0.346
Diabetes	1.996 (0.885–4.500)	0.096
Laparoscopic-assisted surgery	0.403 (0.164–0.991)	0.048	0.286 (0.03–0.797)	0.017a
Hypertension	0.992 (0.484–2.034)	0.984
Type of resection
Total gastrectomy	1.395 (0.671–2.900)	0.373
Operation time (min)	1.008 (1.002–1.015)	0.010	1.008 (1.001–1.015)	0.030a
Blood loss (mL)	1.000 (0.999–1.002)	0.659
History of laparotomy	1.210 (0.505–2.894)	0.669
Albumin (g/dL)	1.041 (0.971–1.116)	0.258
Prealbumin (g/dL)	1.002 (0.996–1.001)	0.508
TNM stage
I	–	–
II	1.629 (0.709–3.743)	0.250
III	0.942 (0.396–2.241)	0.892

^aP < 0.05.

BMI: Body mass index; SFT: Subcutaneous fat thickness; AD: Abdominal depth.

Table 3 Diagnostic value of subcutaneous fat thickness, abdominal depth, and the product of subcutaneous fat thickness and abdominal depth for surgical site infection

	Cutoff value	Sensitivity	Specificity	+LR	−LR	AUC
SFT	16.55	0.850	0.657	2.479	0.228	0.770 (0.700–0.839)
AD	67.85	0.800	0.578	1.895	0.346	0.715 (0.635–0.795)
SFT × AD	11.11	0.875	0.635	2.397	0.197	0.810 (0.740–0.879)

+LR: Positive likelihood ratio; −LR: Negative likelihood ratio; SFT: Subcutaneous fat thickness; AD: Abdominal depth; SFT × AD: The product of SFT and AD.