Neutrophil-to-lymphocyte ratio as a predictor for outcomes in patients with short-term emergency department revisits

Abstract

Background: Analysis of short-term emergency department (ED) revisits is a common emergency care quality assurance practice. Previous studies have explored various risk factors of ED revisits; however, laboratory data were usually omitted. This study aimed to evaluate the prognostic significance of neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte (PLR), and systemic immune-inflammation index (SII) in predicting outcomes of patients revisiting the ED. Methods: This retrospective observational cohort study investigated short-term ED revisit patients. The primary outcome measure was high-risk ED revisit, a composite of in-hospital mortality or intensive care unit (ICU) admission after 72-h ED revisit. The NLR, PLR, and SII were investigated as potential prognostic predictors of ED revisit outcomes. Results: A total of 1916 encounters with short-term ED revisit patients were included in the study; among these, 132 (6.9%) encounters, comprising 57 in-hospital mortalities and 95 ICU admissions, were high-risk revisits. High-risk revisit patients had significantly higher NLR, PLR, and SII (11.6 vs. 6.6, p<0.001; 26.2 vs. 18.9, p=0.004; 2209 vs. 1486, p=0.002, respectively). Multiple regression analysis revealed revisit-NLR as an independent factor for predicting poor outcomes post-ED revisits (Odds Ratio: 1.031, 95% Confidence Interval: 1.017–1.045, p<0.001); an optimal cut-off value of 7.9 was proven for predicting high-risk ED revisit. Conclusion: The intensity of the inflammatory response expressed by NLR was an independent predictor for poor outcomes of ED revisits and should be considered when ED revisits occur. Future prediction models for ED revisit outcomes can include revisit-NLR as a potential predictor to reflect the progressive conditions in ED patients.