Table 3.

Univariate and multivariate regression analysis for risk factors of SSI in the training cohort

Factors	Univariable analysis				Multivariable analysis
	β	OR	95% CI	P value	β	OR	95% CI	P value
Age (years)	0.04	1.04	0.99–1.09	0.115				NI
BMI (kg/m2)	0.04	1.04	0.92–1.17	0.551				NI
Height (mm)	0.01	1.01	0.96–1.06	0.710				NI
Weight (kg)	0.02	1.02	0.98–1.06	0.434				NI
The total volume of drainage (mL)	0.01	1.00	0.99–1.00	0.727				NI
The last volume of drainage (mL)	0.02	1.02	1.00–1.04	0.074				NI
The duration of drainage (days)	− 0.23	0.79	0.55–1.13	0.198				NI
Lengths of admission (days)	0.02	1.02	0.93–1.11	0.586				NI
Albumin (g/L)	− 0.02	0.98	0.88–1.11	0.786				NI
The last CRP (mg/L)	0.01	1.00	0.98–1.02	0.959				NI
The highest WBC count (109/L)	0.04	1.04	0.93–1.16	0.455				NI
The last WBC count (109/L)	− 0.01	1.00	0.87–1.13	0.986				NI
The highest ESR count (mm/h)	0.02	1.02	1.00–1.03	0.069				NI
The last ESR count (mm/h)	0.01	1.01	0.99–1.03	0.392				NI
Gender								NI
Female	Ref	Ref	Ref	Ref
Male	0.45	1.57	0.72–3.57	0.259
Drinking								NI
No	Ref	Ref	Ref	Ref
Yes	0.36	1.43	0.50–3.53	0.467
Smoking								NI
No	Ref	Ref	Ref	Ref
Yes	0.79	2.20	0.90–5.03	0.070
> 7	− 0.31	0.74	0.17–2.30	0.637
The highest CRP (mg/L)	0.01	1.01	1.00–1.02	0.025*	0.01	1.01	0.99–1.03	0.147
Subcutaneous fat thickness (mm)	0.09	1.09	1.03–1.16	0.005*	0.07	1.07	0.97–1.17	0.157
LPM fat infiltration (%)	0.08	1.08	1.05–1.12	< 0.001*	0.08	1.08	1.03–1.14	0.002*
Diabetes
No	Ref	Ref	Ref	Ref
Yes	1.53	4.60	2.10–10.38	< 0.001*	1.19	3.27	1.05–10.74	0.04*
UTIs
No	Ref	Ref	Ref	Ref
Yes	0.99	2.70	1.05–6.42	0.029*	0.81	2.25	0.61–8.17	0.214
Occupation
Sedentary occupation	Ref	Ref	Ref	Ref
Physical work	− 2.78	0.06	0.01–0.42	0.0043*	− 1.95	0.14	0.01–2.72	0.208
Others	− 2.64	0.07	0.01–0.46	0.0054*	− 1.80	0.17	0.01–2.92	0.235
Surgery duration (h)
< 3	Ref	Ref	Ref	Ref
3–4	2.28	9.74	1.79–181.01	0.03*	2.39	10.88	1.63–222.75	0.037*
≥ 4	4.32	75.37	14.74– > 1000	< 0.001*	5.06	157.34	24.05– > 1000	< 0.001*

β regression coefficient; OR odds ratio; 95% CI 95% confidence interval; NI not included; and Ref reference

*P < 0.05

*Statistically significant