Objective: To establish a clinical prediction model for infection risk at the placement sites of skin and soft tissue expanders (hereinafter termed as expanders) and to validate the predictive value of the model. Methods: A retrospective observational study was conducted. Totally 2 934 patients who underwent skin and soft tissue dilatation surgery in the Department of Plastic Surgery of the First Affiliated Hospital of Air Force Medical University from January 2009 to December 2018 and met the selection criteria were included. There were 1 867 males and 1 067 females, with a median age of 18 years. Totally 3 053 skin and soft tissue expansion procedures were performed with 4 266 expanders implanted. The following indexes were selected as predictor variables, including patients' age, gender, marital status, ethnicity, hospital admission, surgical indication, disease duration, with/without history of smoking, history of drinking, history of blood transfusion, history of underlying diseases, and inability to use cephalosporin antibiotics due to allergy, number of expander in a single placement, rated volume of expander, water injection rate of expander in the first time, placement site of expander, anesthesia method, duration of operation, and with/without postoperative hematoma evacuation, and infection at the placement site of expander as the outcome variable. Univariate analysis of the data was performed using least absolute shrinkage and selection operator (LASSO) regression to screen the potential risk factors affecting infection at the placement sites of expanders, the factors selected by the univariate analysis were subjected to binary multivariate logistic regression analysis to screen the independent risk factors affecting infection at the placement sites of expanders, and a nomogram prediction model for the occurrence of infection at the placement sites of expanders was established. The C index and Hosmer-Lemeshow goodness of fit test were used to evaluate the discrimination and accuracy of the model, respectively, and the bootstrap resampling was used for internal verification. Results: The results of LASSO regression showed that age, gender, hospital admission, surgical indication, disease duration, history of drinking, history of heart disease, history of viral hepatitis, history of hypertension, inability to use cephalosporin antibiotics due to allergy, number of expander in a single placement, rated volume of expander, placement site of expander, postoperative hematoma evacuation were the potential risk factors for infection at the placement sites of expanders (regression coefficient=-0.005, 0.170, 0.999, 0.054, 0.510, -0.003, 0.395, -0.218, 0.029, 0.848, -0.116, 0.175, 0.085, 0.202). Binary multivariate logistic regression analysis showed that male, emergency admission, disease duration ≤1 year, inability to use cephalosporin antibiotics due to allergy, rated volumes of expanders ≥200 mL and <400 mL or ≥400 mL, and expanders placed in the trunk or the limbs were the independent risks factors for infection at the placement sites of expanders (odds ratio=1.37, 3.21, 2.00, 2.47, 1.70, 1.73, 1.67, 2.16, 95% confidence interval=1.04-1.82, 1.09-8.34, 1.38-2.86, 1.29-4.41, 1.07-2.73, 1.02-2.94, 1.09-2.58, 1.07-4.10, P<0.05 or P<0.01). The C index for evaluating the discriminative degree of the model was 0.63, the Hosmer-Lemeshow goodness of fit test for evaluating the accuracy of the model showed P=0.685, and the C index for internal validation by the bootstrap resampling was 0.60. Conclusions: Male, emergency admission, disease duration ≤1 year, inability to use cephalosporin antibiotics due to allergy, rated volume of expander ≥200 mL, and expanders placed in the trunk or the limbs are the independent risk factors for infection at the placement sites of expanders. The clinical prediction model for infection risk at the placement sites of expanders was successfully established based on these factors and showed a certain predictive effect.
目的： 构建皮肤软组织扩张器（以下简称扩张器）置入部位感染风险的临床预测模型并验证其预测价值。 方法： 采用回顾性观察性研究方法。纳入符合入选标准的2009年1月—2018年12月于空军军医大学第一附属医院整形外科行皮肤软组织扩张术患者2 934例，其中男1 867例、女1 067例，中位年龄18岁，行皮肤软组织扩张术3 053例次，置入扩张器4 266个。以患者年龄、性别、婚姻状况、民族、入院方式、手术指征、患病时间，有无吸烟史、饮酒史、输血史、基础疾病史、因过敏无法使用头孢菌素类抗生素，单次置入扩张器数量、扩张器额定容积、扩张器首次注水率、扩张器置入部位、麻醉方式、手术时长、有无术后血肿清除为预测变量，以扩张器置入部位感染为结局指标。对数据采用最小绝对值压缩和选择算法（LASSO）回归行单因素分析，筛选影响扩张器置入部位感染的可能危险因素；对单因素分析筛选出的因素行二分类多因素logistic回归分析，筛选影响扩张器置入部位感染的独立危险因素并建立发生扩张器置入部位感染的列线图预测模型。使用C指数和Hosmer-Lemeshow拟合优度检验评价模型的区分度和准确度，采用自助重采样法进行内部验证。 结果： LASSO回归分析显示，年龄、性别、入院方式、手术指征、患病时间、饮酒史、心脏病史、病毒性肝炎史、高血压史、因过敏无法使用头孢菌素类抗生素、单次置入扩张器数量、扩张器额定容积、扩张器置入部位、术后血肿清除为影响扩张器置入部位感染的可能危险因素（回归系数=-0.005、0.170、0.999、0.054、0.510、-0.003、0.395、-0.218、0.029、0.848、-0.116、0.175、0.085、0.202）。二分类多因素logistic回归分析显示，男性、急诊入院、患病时间≤1年、因过敏无法使用头孢菌素类抗生素、扩张器额定容积≥200 ml且<400 mL或≥400 mL、扩张器置入部位为躯干或四肢等是扩张器置入部位感染的独立危险因素（比值比=1.37、3.21、2.00、2.47、1.70、1.73、1.67、2.16，95%置信区间=1.04~1.82、1.09~8.34、1.38~2.86、1.29~4.41、1.07~2.73、1.02~2.94、1.09~2.58、1.07~4.10，P<0.05或P<0.01）。评价模型区分度的C指数=0.63（95%置信区间=0.59~0.66），评价模型准确度的Hosmer-Lemeshow拟合优度检验，P=0.685。自助重采样法内部验证模型的C指数=0.60。 结论： 男性、急诊入院、患病时间≤1年、因过敏无法使用头孢菌素类抗生素、扩张器额定容积≥200 mL、扩张器置入部位为躯干或四肢是扩张器置入部位感染的独立危险因素，基于这些因素构建的扩张器置入部位感染风险的临床预测模型构建成功，并具有一定的预测效能。.