[Surgical site infection after colorectal surgery in China from 2018 to 2020]

Objective: This study aims to survey the incidence of surgical site infection (SSI) in China and to analyze its risk factors, so as to prevent and control SSI after colorectal surgery. Methods: An observative study was conducted. Based on a program of Chinese SSI Surveillance from 2018 to 2020, the clinical data of all adult patients undergoing colorectal surgery during this time period were extracted. These included demographic characteristics and perioperative clinical parameters. Minors, pregnant women, obstetric or gynecological surgery, urological system surgery, retroperitoneal surgery, resection of superficial soft tissue masses, and mesh or other implants were excluded. A total of 2122 patients undergoing colorectal surgery from 50 hospitals were included, including 1252 males and 870 females. The median age was 63 (16) years and the median BMI was 23 (4.58) kg/m². The primary outcome was the incidence of SSI within 30 days after colorectal surgery. The secondary outcomes were mortality within 30 days postoperatively, length of ICU stays and postoperative hospital stays, and cost of hospitalization. Patients were divided into the SSI group and non-SSI group based on the occurrence of SSI. Multivariable logistic regression was performed to analyze risk factors of SSI after colorectal surgery, and subgroup analysis was conducted for open and laparoscopic surgery. Results: The incidence of SSI after colorectal surgery was 5.6% (119/2122), including 47 cases (47/119, 39.5%) with superficial incisional infections, 24 cases (24/119, 20.2%) with deep incisional infections, and 48 cases (48/119, 40.3%) with organ/space infections. The occurrence of SSI significantly increased mortality [2.5% (3/119) vs. 0.1%(3/2003), χ²=22.400, P=0.003], the length of ICU stay [0 (1) day vs. 0(0) day, U=131 339, P<0.001], postoperative hospital stay [18.5 (12.8) days vs. 9.0 (6.0) days, U=167 902, P<0.001], and medical expenses [75 000 (49 000) yuan vs. 60 000 (31 000) yuan, U=126 189, P<0.001] (P<0.05). Multivariate analysis revealed that hypertension (OR=1.782, 95%CI: 1.173-2.709, P=0.007), preoperative albumin level (OR=1.680, 95%CI: 1.089-2.592, P=0.019), a contaminated or infected incision (OR= 1.993, 95%CI: 1.076-3.689, P=0.028), emergency surgery (OR=2.067, 95%CI: 1.076-3.972, P=0.029), open surgery (OR=2.132, 95%CI: 1.396-3.255, P<0.001), and surgical duration (OR=1.804, 95%CI: 1.188-2.740, P=0.006) were risk factors for SSI, while preoperative skin preparation (OR=0.478, 95%CI: 0.310-0.737, P=0.001) was a protective factor for SSI. Subgroup analysis was performed on patients undergoing open or laparoscopic surgery. The incidence of SSI in the open surgery group was 10.2%, which was significantly higher than that in the laparoscopic or robotic group (3.5%, χ²=39.816, P<0.001). Subgroup analysis identified that a contaminated or infected incision (OR=2.168, 95%CI: 1.042-4.510, P=0.038) and surgical duration (OR=2.072, 95%CI: 1.171-3.664, P=0.012) were risk factors for SSI after open surgery, while mechanical bowel preparation (OR=0.428, 95%CI: 0.227-0.807, P=0.009) and preoperative skin preparation (OR=0.356, 95%CI: 0.199-0.634, P<0.001) were protective factors for SSI after open surgery. In laparoscopic surgery, diabetes mellitus (OR= 2.292, 95%CI: 1.138-4.617, P=0.020) and hypertension (OR=2.265, 95%CI: 1.234-4.159, P=0.008) were risk factors for SSI. Conclusions: The incidence of SSI after colorectal surgery is 5.6%. Minimally invasive surgery should be selected to reduce the occurrence of postoperative SSI. To prevent the occurrence of SSI after open surgery, skin preparation and mechanical bowel preparation should be performed before the operation, and the duration of the operation should be shortened as much as possible. In the perioperative period, care of patients with hypertension, diabetes, and contaminated or infected incisions should be given particular attention.