Severe Preoperative Infection and Postoperative Acute Kidney Injury in Children: A Two-Hit Risk Factor for Mortality

BACKGROUND: Children with severe preoperative infections are at increased risk for postoperative complications, yet the association between preoperative sepsis or systemic inflammatory response syndrome (SIRS) and subsequent acute kidney injury (AKI) in pediatric surgical patients remains to be fully explored. We evaluated whether severe preoperative infections increase the risk of postoperative AKI and examined the combined impact of preoperative infections and postoperative AKI on 30-day mortality in pediatric surgical patients. METHODS: We performed a retrospective cohort study of 144,718 propensity score–matched children younger than 18 years who underwent inpatient surgery, using data from the National Surgical Quality Improvement Program–Pediatric (2012–2023). Severe preoperative infection was defined as sepsis or SIRS within 48 hours before surgery. Postoperative AKI included acute renal failure or progressive renal insufficiency occurring within 30 days. Adjusted risk ratios (aRRs) were estimated using modified Poisson regression. RESULTS: Postoperative AKI occurred in 200 children (0.14%). Severe preoperative infection was associated with more than double the risk of postoperative AKI (aRR, 2.03; 95% confidence interval [CI], 1.51–2.74; P < .001). Postoperative AKI conferred a 4.6-times associated risk of 30-day mortality (aRR, 4.64; 95% CI, 3.48–6.12; P < .001), and preoperative infection alone was associated with a 1.8-times increase in mortality risk (aRR, 1.83; 95% CI, 1.60–2.10; P < .001). When both conditions occurred, the risk of 30-day mortality was nine times higher (aRR, 9.63; 95% CI, 7.20–12.87; P < .001) on an additive interaction scale. CONCLUSIONS: Severe preoperative infection is associated with a higher risk of postoperative AKI and 30-day mortality after adjustment for measured confounders. The combination of preoperative infection and postoperative AKI produces a nine-fold higher risk of mortality, underscoring the need for targeted perioperative strategies in high-risk pediatric populations.