Development of a novel clinical and radiological 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.