Efficacy of subcutaneous penrose drains for surgical site infections in colorectal surgery

Table 1 Demographic characteristics of the patients in the two periods

	Prior period (n = 131)	Latter period (n = 151)	P value
Age (yr, mean ± SD)	62.7 ± 10.4	63.0 ± 12.4	0.847
Sex (male/female)	68/63	91/60	0.158
Diabetes mellitus (yes/no)	17/114	20/131	0.947
Smoking history (yes/no)	24/107	32/119	0.547
ASA classification (ASA score ≤ 2/3 ≤)	124/7	146/5	0.399
Body mass index (kg/m2)	22.4 ± 3.3	22.5 ± 3.5	0.802
Subcutaneous fat (mm, mean ± SD)	18.2 ± 7.8	19.7 ± 7.1	0.081
Site (colon/rectum)	73/58	95/56	0.220
Operation time (min, median)	206	219	0.864
Blood loss(mL, median)	205	200	0.169
Stoma (yes/no)	32/99	31/120	0.433
Patients with high risk1	40	75	0.001
Patiens with PD	0	151

¹High risk patients whose depth of subcutaneous tissue are over 20 mm. ASA: American Society of Anesthesiologists; PD: Penrose drains.