A model for predicting the systemic inflammatory response syndrome after flexible ureteroscope lithotripsy for upper urinary tract calculi

Abstract

Objective To analyze the risk factors that affect severe infection following flexible ureteroscope Holmium laser lithotripsy for upper urinary tract calculus, and to construct the regression model and nomogram for predicting the probability of postoperative SIRS. Methods We retrospectively analyzed the clinical data from 457 cases (male 302 and female 155) of upper urinary calculi treated by flexible ureteroscopy from January 2014 to May 2016, with mean age of 49.9 (ranged 20-76) years. The mean maximum size of stones was (16.5±3.0)mm (ranged 12-22mm). There were 51 cases (11.2%) with a recent infectious febrile history related to stones. The patients were divided into two groups as patients developing SIRS or not. Univariate and multivariate statistical analyses were performed to determine factors affecting the development of postoperative SIRS, and then a nomogram was built based on regression coefficients. Results The incidence of SIRS after flexible ureteroscopic lithtripsy was 5.9% (27/457). Multivariable logistic regression analysis identified febrile history related to urinary stones (OR=1.5569, P=0.009), without preoperative placement of ureteral stent (OR=1.4004, P=0.004), small-caliber (F 13-14)ureteral access sheath (OR=1.1120, P=0.016), endoscopic signs of infection (OR=2.0176, P=0.000) and infectious stones (OR=1.0981, P=0.013) as independent risk factors for postoperative SIRS. The concordance index was 0.845 in the nomogram model sample and 0.79 in the validation sample. Conclusions Febrile history related to urinary stones, without preoperative placement of ureteral stent, small-caliber ureteral access sheath, endoscopic signs of infection and infectious stones would be independent risk factors to predict SIRS after flexible ureteroscope holmium laser lithtripsy. A nomogram based on perioperative clinical factors could be used to predict the risk of SIRS. Key words: Flexible ureteroscopy; Lithotripsy, laser; Systemic inflammatory response syndrome; Risk factors; Nomogram