Comparing the Prognostic Value of Lactate to the Neutrophil to Lymphocyte Ratio Among Sepsis Patients: a Prospective Cohort Study

Abstract Background The prognostic role of the neutrophil to lymphocyte ratio (NLR) was studied in several disease conditions such as appendicitis, cardiovascular disease, malignancy, and sepsis. Lactate is a commonly used prognostic biomarker in sepsis. The aim of this study was to compare the prognostic value of lactate to the neutrophil-to-lymphocyte ratio among septic patients. Methods This was a prospective cohort study including adult septic or septic shock patients presenting to the Emergency Department of a tertiary care center, between September 2018 and February 2021. The primary outcome was to compare the prognostic value of the NLR to lactate with regard to in-hospital mortality. The secondary outcome was to compare the prognostic value of the NLR to lactate in different septic patient subgroups with regard to in-hospital mortality. Results The number of septic patients included in this study was 874. In the stepwise logistic regression, NLR was not associated with in-hospital mortality (OR = 1.003, 95% CI = 0.994–1.012, p = 0.544), whereas lactate was associated with in-hospital mortality (OR = 1.188, 95% CI = 1.086–1.299, p < 0.0001). There was no statistically significant difference between the AUC of NLR and lactate (0.552 95% CI = 0.504–0.599 vs 0.591 95% CI = 0.544–0.637, p = 0.22). Lactate outperformed NLR in the following subgroups: albumin < 30, patients less than 65 years of age and patients with sepsis due to a urinary tract infection. There was no statistically significant difference in the AUCs between lactate and NLR in patients with septic shock, Lactate < 2, Lactate ≥ 2, diabetes, malignancy, chronic kidney diseases, other sources of infection, albumin ≥ 30 and age ≥ 65. Conclusion In this study, lactate but not NLR was associated with in-hospital mortality. There was no significant difference in the AUCs between lactate and NLR among sepsis patients and among the majority of the subgroups in this study (including septic shock patients). However, lactate outperformed NLR in the following subgroups: albumin < 30 g/L, patients less than 65 years of age and patients with sepsis due to a urinary tract infection. Our results advocate for the continued use of serum lactate rather than NLR, despite its limitations, as a predictor of mortality among septic patients and the different subgroups in this study.