Predicting Sepsis in Patients with Ureteral Stones in the Emergency Department

Background: In the absence of overt infection signs, clinical criteria for early intervention in patients with ureteral stones are poorly defined. We aimed to develop a model that can identify patients who are at risk for developing sepsis if discharged home from the emergency department (ED). Materials and Methods: We retrospectively reviewed patients between January 2010 and December 2019 who were discharged from the ED after diagnosis of ureteral stones. The primary outcome was sepsis requiring urgent surgical decompression. We used multivariable logistic regression to identify predictors of sepsis. We refined the model using backward stepwise regression with a threshold p-value of 0.05. Results: We identified 1331 patients who were discharged from the ED with ureteral stones. Of these patients, 22 (2%) subsequently developed sepsis requiring urgent decompression. In the initial multivariable model, female gender (odds ratio [OR]: 2.82, p = 0.039) and urine white blood cells (WBCs) (OR: 1.02 per cell count, p < 0.001) were predictive of sepsis. After performing backward stepwise regression, female gender, urine WBCs, and leukocytosis (WBCs > 15,000/mm(3)) met criteria for inclusion in the model. A logistic model including these variables predicted sepsis with an internally cross-validated area under the curve (AUC) of 0.79. Among patients with urine cultures completed in the ED, rates of sepsis were 9% in patients with positive cultures and 1% in patients with negative cultures (p < 0.001). Antibiotic usage was not protective against developing sepsis. Conclusions: Sepsis is a rare complication among patients with ureteral stones selected for conservative management. The presence of elevated urine WBCs and female gender can help identify patients who are at risk of developing sepsis. Patients with risk factors should be managed with an increased index of suspicion for infection and may benefit from early intervention to reduce the risk of sepsis. Sepsis is more common in patients with positive urine cultures.