Predictive Value of Systemic Immune Inflammation Index in Septic Patients with Acute Kidney Injury

Background: Acute kidney injury (AKI) is common in patients with sepsis and may result in death. Systemic immune inflammation index (SII) is associated with kidney injury, but its predictive value for AKI in patients with sepsis remains unclear. Objective: This study aimed to explore the predictive value of SII in sepsis patients with AKI. Methods: From January 2020 to December 2022, 221 patients with sepsis treated in our hospital were retrospectively collected. The patients were divided into AKI group (n = 61) and control group (n = 160). Clinical characteristics and SII level were compared between the two groups, and the predictive value of SII for the occurrence of AKI was analysed. Results: The SII level (724.72 ± 235.50 vs. 522.38 ± 205.62, p < 0.001), the serum procalcitonin level (8.13 ± 15.52 vs. 4.52 ± 10.34 µg/L, p < 0.001), and the acute physiology and chronic health evaluation II score (14.26 ± 2.90 vs. 11.62 ± 2.26, p < 0.001) significantly increased in the AKI group compared with the control group, whereas the albumin level significantly decreased (30.60 ± 5.41 vs. 32.49 ± 5.31 g/L, p = 0.019). The receiver operating characteristic curve showed that SII was valuable in predicting AKI in patients with sepsis, with an area under the curve of 0.733 (95% confidence interval: 0.657–0.810, p < 0.001). The continuous renal replacement therapy intervention rate (88.52% vs. 0.00%, p < 0.001), the intervention rate of vasoactive drugs (34.43% vs. 3.75%, p < 0.001), and the hospital mortality rate (16.39% vs. 2.50%, p < 0.001) significantly increased in the AKI group compared with the control group. Conclusions: AKI was associated with poor prognosis in patients with sepsis. SII, procalcitonin and acute physiology and chronic health evaluation II (APACHE II) score were valuable in predicting the occurrence of AKI. SII may serve as a new marker in patients with sepsis.