Construction of a Nomogram Model for Individualized Prediction of the Risk of Postoperative Incision Infection in Elderly Patients with Traumatic Limb Fracture

Objective To explore the influencing factors of incision infection in elderly patients with traumatic limb fracture after surgery, and to construct a nomographic model. Methods A total of 360 elderly patients with traumatic limb fracture who received surgical treatment in the First Affiliated Hospital of Chengdu Medical College from May 2021 to September 2023 were selected as the study subjects and divided into the modeling group (n = 252) and the verification group (n = 108) by the computer random number table. LASSO regression and logistic regression were used to analyze the influencing factors of postoperative incision infection, and column line diagrams were constructed according to the influencing factors, and the predictive performance and effect of the risk prediction model were evaluated by ROC curve and calibration curve. Results Twenty-seven research variables were included in the LASSO regression model for screening, and two models were constructed based on minimum values and standardization. Model 1 included 12 variables, including body mass index (BMI), use of steel plate, diabetes, drainage tube placement time, incision type, operation time, incision length, the ratio of peripheral blood C-reactive protein to albumin (CAR), serum procalcitonin (PCT)/albumin (ALB), interleukin-6 (IL-6), neutrophil to lymphocyte ratio (NLR), and serum erythrocyte sedimentation rate (ESR) three days after operation. Seven variables were included in model 2, including diabetes, drainage tube placement time, and peripheral blood CAR, PCT/ ALB, IL-6, NLR, ESR 3 days after surgery. The logistic regression analysis models were constructed with the dependent variable of whether the incision infection occurred after surgery, and the variables screened by LASSO regression in model 1 and model 2 as independent variables. The results of model 1 showed that BMI ≥28 kg/ m2, combined with diabetes, incision type Ⅲ, operation time, incision length, use of steel plate, placement time of drainage tube ≥ 6 days, and peripheral blood CAR, PCT/ ALB, IL-6, NLR, ESR 3 days after surgery were independent risk factors for postoperative incision infection in elderly patients with traumatic limb fracture (P < 0.05) . The results of model 2 showed that the combination of diabetes, the placement time of drainage tube ≥6 days and the peripheral blood CAR, PCT/ ALB, IL-6, NLR, ESR 3 days after operation were independent risk factors for postoperative incision infection in elderly patients with traumatic limb fracture (P < 0.05) . The area under the ROC curve of Model 1 in the modeling and validation groups was respectively 0.949 (95% CI: 0.898 - 1.000) and 0.981 (95% CI: 0.956 - 1.000), respectively. The results of the Hosmer Lemeshow test for Model 1 in the modeling and validation groups showed that the model did not deviate from a perfect fit, and the consistency of the calibration curve was good. The area under the ROC curve of Model 2 in the modeling and validation groups was respectively 0.882 (95% CI: 0.787 - 0.977) and 0.921 (95% CI: 0.843 - 1.000), respectively. Furthermore, the Hosmer Lemeshow test of Model 2 in the modeling and validation groups showed that the model deviated from a perfect fit and the consistency of the calibration curve was poor. Conclusion BMI, combined diabetes, incision type, operation time, incision length, use of steel plate, placement time of drainage tube, CAR, PCT/ ALB, IL-6, NLR and ESR of peripheral blood 3 days after operation are the influencing factors of postoperative incision infection in elderly patients with traumatic limb fracture.