| Objective:To analyze the risk factors related to urethral skin fistula following hypospadias surgery in urology,and the predictive model for the risk factors of urethral skin fistula was established.This study provides an important evidence to choose whether urethral skin fistula occurs after hypospadias repair and correction in clinical,and to appropriate clinical intervention measures should be taken as soon as possible to reduce the incidence of postoperative urethral fistula in children,as well as better communication with patients and their families.Methods:1.To investigate the patients with urethral skin fistula after operation,this study analyzed those patients with hypospadias who underwent primary repair and correction in Huaihe Hospital of Henan University,from January 2017 to December 2021,retrospectively.A total of 99 male patients who underwent hypospadias repair and correction were included in this study.The Nine independent variables were conducted in this study,including age,hypospadias classification,length of hypospadias defect,degree of ventral curvature of the penis,presence or absence of consolidated cryptorchidism,surgical method,presence or absence of postoperative infection,presence or absence of postoperative blood supply disorder,presence or absence of postoperative distal urethral obstruction,and one dependent variable that presence or absence of postoperative urethral skin fistula was identified.2.To analyze the above variables,T test(normal distribution)or rank sum test(non-normal distribution)was performed to obtain T value or Z value and corresponding P value for continuous variables.For the grade variables and categorical variables,the chi-square test data analysis was performed to obtain the X~2value and the corresponding P value,so as to obtain statistical significant(p<0.05)variables.which was included in the multi-factor model for Logistic regression analysis.The results of statistical analysis were obtained and the prediction model of urethral skin fistula after hypospadias surgery was constructed.Variance Inflation Factor(VIF)was used for collinearity analysis of the above statistical significant variables to exclude linear correlation.Meanwhile,Akaike information criterion(AIC)was used to screen out a better prediction model,and then the equation was established.The four risk factors related to the dependent variables were selected for receiver operating characteristic curve(ROC)analysis to test their discrimination.The statistical significant variables screened above were internally verified by Bootstrap self-sampling method,.To operate characteristic curve(ROC curve)of the verification group to test the differentiation of the model,and the Hosmer-Lemeshow goodness of fit test was used.3.The nomogram model was constructed furtherly,and the Calibration curve was used to evaluate the conformity results between the actual and the nomogram prediction.Finally,the decision curve analysis(DCA curve)was used to judge the clinical utility of the nomogram.The receiver operating characteristic curve,calibration curve and decision curve were analyzed for the evaluation of the prediction model.Results:1.A total of 99 male patients undergoing hypospadias repair were reviewed in this study,including 27patients(27.27%)with urethral skin fistula,and without for 72 patients(72.72%).2.After being put on record and reviewed by the hospital ethics committee,patients’case data were collected anonymously.The nine independent variables were conducted in this study,including age,hypospadias classification,length of hypospadias defect,degree of ventral curvature of the penis,presence or absence of consolidated cryptorchidism,surgical method,presence or absence of postoperative infection,presence or absence of postoperative blood supply disorder,presence or absence of postoperative distal urethral obstruction,and one dependent variable that presence or absence of postoperative urethral skin fistula was identified.Univariate statistical analysis was performed on the independent variables,The results showed that the X~2value of the presence or not about cryptorchidism was 4.787 and the P was 0.029.The X~2value of postoperative infection was 7.381 and the P was 0.007.The X~2value of postoperative blood supply disorder was 15.916 and the P<0.001.The X~2value of postoperative distal urethral obstruction was 22.066 and the P<0.001.The P values of the other variables were more than 0.05.The four variables of presence or not about consolidated cryptorchidism,postoperative infection,postoperative blood supply disorder and postoperative distal urethral obstruction were significant difference(p<0.05).which further included in Logistic multivariate regression analysis.The four variables of presence or not about consolidated cryptorchidism,postoperative infection,postoperative blood supply disorder and postoperative distal urethral obstruction were independent risk factors for urethral skin fistula after hypospadias repair and correction.Their corresponding regression coefficients were 2.8591,2.8709,3.5710and 4.1051,respectively.Furthermore,the optimal prediction model was screened out by collinearity analysis and Akaike information criterion(AIC),According to the risk factors of urethral skin fistula after hypospadias repair and correction,the prediction model was Logit(P)=-2.1455+2.8591×(presence or not about consolidated cryptorchidism)+2.8709×(presence or not about infection after operation)+3.5710×(presence or absence blood supply disorder after operation)+4.1051×(presence or absence distal urethral obstruction after operation).The above four risk factors were analyzed by ROC analysis,and then the ROC curve was identified.The area under the ROC curve(AUC)was 0.833(95%CI0.7403-0.9248),and the sensitivity degree was 0.704 with 0.944 for specificity,indicating that a good discrimination.Besides,Bootstrap self-help sampling method was used for internal verification,and Hosmer-Lemeshow goodness of fit test was used.Those results showed that the risk prediction model constructed in the study had good fit.3.According to the results above,the nomogram was constructed for predicting the risk factors of urethral skin fistula after hypospadias repair and correction.The Calibration curve showed that the calibration of the prediction model performed well.The decision curve analysis(DCA)showed that,the clinical application value and benefit of the prediction model were showed with higher.Conclusion:This study shows that the presence or not about consolidated cryptorchidism,postoperative infection,postoperative blood supply disorder,and postoperative distal urethral obstruction are independent risk factors for urethral skin fistula after hypospadias repair and correction.Based on these risk factors,a prediction model of risk factors for urethral skin fistula after hypospadias repair and correction was constructed,the Logit(P)=-2.1455+2.8591×(presence or not on cryptorchidism)+2.8709×(presence or not on postoperative infection)+3.5710×(presence or not on blood supply disorder)+4.1051×(presence or not on distal urethral obstruction).and then The risk prediction nomogram model was further constructed.It was determined by drawing the Calibration curve,that the prediction accuracy of the prediction model shows better application.Furthermore,the decision curve analysis also verified that the prediction model shows better for clinical application value,which provides an important basis to judge the urethral skin fistula occurs after hypospadias repair surgery in clinical,and provides the better guidance for patients and their family members. |
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