Preoperative positive urine nitrite and albumin-globulin ratio are independent risk factors for predicting postoperative fever after retrograde Intrarenal surgery based on a retrospective cohort

BACKGROUND: To determine risk factors for postoperative fever (POF) after retrograding intrarenal surgery (RIRS) and a nomogram for prediction of POF in patients undertaking RIRS has been developed based on the risk factors found. METHODS: This is a retrospective designed-study. A continuous cohort from a single-center database that consisted of 1095 cases undertaking RIRS with complete preoperative medical records from January 2009 to December 2018 was obtained. Independent risk factors were identified according to the multi-variate logistics regression and a further nomogram was developed. The performance of the nomogram was evaluated through three aspects including net clinical benefit, calibration, and discrimination. RESULTS: A total of 31(2.8%) cases had POF after the RIRS. Risk factors included time in RIRS ≥30mins (only the flexible scope use period) (OR: 2.16, 95%CI; 1.01–4.62, P = 0.047), preoperative positive urine culture (OR: 2.55, 95%CI; 1.01–6.42, P = 0.047), preoperative positive urine nitrite (OR: 9.09, 95%CI; 2.99–27.64, P < 0.001), Albumin/globulin ratio (AGR) (OR: 0.14, 95%CI; 0.03–0.74, P = 0.020) were further included in the nomogram to predict the POF probability for individuals. The Hosmer-Lemeshow test showed a goodness-of-fit. The calibration curve demonstrated good agreement between observation and prediction. Decision curve analysis (DCA) demonstrated it was clinical use in RIRS. CONCLUSIONS: The preoperative urine nitrite, AGR, RIRS time, and preoperative urine culture are found to be independent risk factors associated with POF after RIRS. Then we have developed a nomogram taking these factors into account that accurately predicted POF after RIRS.