Neutrophil to lymphocyte and platelet ratio as a prognostic marker of short-term mortality and disease severity in sepsis-associated acute kidney injury patients in the intensive care unit: a retrospective study

Abstract

Abstract Background:Sepsis-associated acute kidney injury (S-AKI) is a common and life-threatening complication in critically ill patients. The neutrophil to lymphocyte and platelet (N/LP) ratio has been identified as a risk factor for the development of S-AKI. However, the relationship between the N/LP ratio and adverse outcomes in S-AKI patients remains unclear. Therefore, the aim of this study was to investigate the prognostic value of the N/LP ratio in S-AKI patients and its potential application in early identification of short-term mortality and severity of AKI. Methods: We conducted a retrospective analysis of patients diagnosed with S-AKI at our institution between January 2015 and July 2023. Sepsis was diagnosed according to the Sepsis-3 criteria, while AKI diagnoses were made following the KDIGO guideline. The primary objective of this study was to evaluate the 30- and 60-day mortality rates among these patients. Additionally, we also aimed to assess the incidence of severe AKI as a secondary endpoint measure. Results: In this study, a total of 483 patients with S-AKI were included, with a median age of 76.0 (67.0-84.0) years and 296 (61.3%) being male. Among these patients, 332 (68.7%) were classified as stage 1, 79 (16.4%) as stage 2, and 72 (14.9%) as stage 3 AKI. The 30-day mortality rate was 38.9%, and the 60-day mortality rate was 44.3%. Patients in the high N/LP ratio group, as determined by the median at ICU admission, had an increased risk of 30- and 60-day mortality, as well as a higher occurrence of severe AKI (stages 2 and 3). In multivariate Cox proportional hazard models, the high N/LP group exhibited a 1.728-fold increase in 30-day mortality and a 1.702-fold increase in 60-day mortality compared to the low N/LP group. Similarly, in a multivariate logistic regression model, the high N/LP group had a 1.634-fold increased risk of severe AKI occurrence. Spearman's analysis revealed a positive correlation between the N/LP ratio and APACHE II and SOFA scores. Subgroup analyses showed that the association between the N/LP ratio and 30-/60-day mortality and severe AKI occurrence did not differ significantly across strata such as age, hypertension, diabetes, and SOFA score, except for gender and smoking status. Furthermore, the ROC analysis indicated that the initial N/LP ratio at ICU admission had the highest area under the curve (AUC) of 0.652 and 0.635 for 30- and 60-day mortality prediction, respectively, compared to other biomarkers such as WBC, Neu, Lym, Hb, PLT, CRP, Alb, BUN, uric acid, and lactate. Additionally, the N/LP ratio was found to have good predictive power for severe AKI (AUC: 0.596) in S-AKI prognosis. Conclusions: The N/LP ratio, which can be easily obtained from routine blood analysis, was independently associated with both 30-/60-day mortality and the occurrence of severe AKI in S-AKI patients.