Fever and systemic inflammatory response syndrome after retrograde intrarenal surgery: Risk factors and predictive model

This paper investigates the characteristics of patients who underwent retrograde intrarenal surgery (RIRS) to determine the predictive factors for post-operative fever and systemic inflammatory response syndrome (SIRS) and to construct a predictive nomogram to help with risk-stratification. A retrospective study of 337 patients who underwent RIRS was performed. Fever and SIRS were defined according to a previous consensus. Multivariate logistic regression coefficients were used to generate nomograms. Post-operative fever was found in 59 patients (17.5%), and SIRS was found in 22 patients (6.5%). Septic shock developed in 2 patients (0.6%). Three patients (0.9%) suffered from obstructive hydronephrosis. By multivariate analysis, concomitant diabetes mellitus (p = 0.015), high pre-operative C-reactive protein (CRP) (p = 0.015), long surgical times (p = 0.007), high stone burden (p = 0.004) and positive stone culture (p = 0.003) were independent risk factors for fever. Only high pre-operative CRP (p = 0.001), long surgical times (p = 0.001) and high stone burden (p = 0.001) were found to significantly affect the occurrence of SIRS. Predictive nomograms were built for fever and SIRS and the c-statistics for the two predictive models were 0.766 and 0.887, respectively. All patients recovered well after proper treatment, which included antipyretics, antibiotics, and inotropic support and nephrostomy when needed. In conclusion, high stone burden, long surgical time, positive stone culture, high pre-operative CRP and the presence of diabetes mellitus was could increase the risk of fever or SIRS after RIRS for kidney stone. The constructed nomograms could help clinicians in evaluating the risk for post-operative infectious complications. Keywords: Fever, Infection, Nomogram, Retrograde intrarenal surgery (RIRS), Systemic inflammatory response syndrome (SIRS)