Development of a Novel Clinical and Radiologic Risk Score to Predict Septic Complications After Urinary Decompression in Patients with Obstructive Uropathy

Background Well-defined clinical predictors of sepsis after upper tract drainage for obstructive uropathy are lacking. The study aim is to develop a data driven score to predict risk of sepsis after decompression of the upper urinary tract. Materials and methods Complete clinical and radiological data from 271 patients entering the emergency department for obstructive uropathy and submitted to stent/nephrostomy tube decompression were evaluated. The Charlson Comorbidity Index (CCI) was used to score comorbidities. The definition of sepsis was an increase in ≥2 SOFA points (or postoperative persistently elevated score +1 additional increase) and documented blood or urine cultures. Descriptive statistics and stepwise multivariable logistic regression modelling with ROC analysis were performed in order to obtain a composite risk score to predict the risk of sepsis after surgery. Results Fifty-five (20.3%) patients developed sepsis. At multivariable analysis, CCI ≥2 (OR 3.10; 95%CI 1.36-7.04), max body temperature ≥38°C (OR 4.35; 95%CI 1.89-9.44), grade III-IV hydronephrosis (OR 2.37; 95%CI 1.10-4.98), Hounsfield units of the dilated collecting system ≥7.0 (OR 4.47; 95%CI 2.03-9.81), WBC ≥15x103/mmc (OR 2.77; 95%CI 1.24-6.19) and C-reactive protein ≥10 (OR 3.27; 95%CI 1.41-7.56) were independently associated with sepsis. The PPV of a true sepsis increased incrementally as a function of number of positive variables, ranging from 1.6% to 100.0% among patients with 1 and 6 positive variables, respectively. Conclusion Our risk score identifies accurately patients with an increased risk of sepsis after urinary decompression for obstructive uropathy, hence improving clinical management.