Mehmet Muzaffer Islam, Merve Osoydan Satici, Serkan Emre Eroglu

Department of Emergency Medicine, University of Health Sciences, Umraniye Training and Research Hospital, Istanbul, Turkey

Keywords: Delta neutrophil index, neutrophil‑to‑lymphocyte ratio, platelet‑to‑lymphocyte ratio, systemic immune inflammation index, systemic inflammation response index


In the field of critical care medicine, substantial research efforts have focused on identifying high risk patient groups. This research has led to the development of diverse diagnostic tools, ranging from basic biomarkers to complex indexes and predictive algorithms that integrate multiple methods. Given the ever evolving landscape of medicine, driven by rapid advancements, changing treatment strategies, and emerging diseases, the development and validation of diagnostic tools remains an ongoing and dynamic process. Specific changes in complete blood count components, such as neutrophils, lymphocytes, monocytes, and platelets, are key immune system responses influenced by various factors and crucial in systemic inflammation, injury, and stress. It has been reported that indices such as neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR), systemic immune inflammation index (SII), systemic inflammation response index (SIRI), and delta neutrophil index calculated using various ratios of these elements, are important predictors of various outcomes in conditions where the inflammatory process is at the forefront. In this narrative review, we concluded that NLR, PLR, SII, and SIRI show promise in predicting outcomes for different health conditions related to inflammation. While these tests are accessible, reliable, and cost effective, their standalone predictive performance for a specific condition is limited.

How to cite this article: Islam MM, Satici MO, Eroglu SE. Unraveling the clinical significance and prognostic value of the neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio, systemic immune‑inflammation index, systemic inflammation response index, and delta neutrophil index: An extensive literature review. Turk J Emerg Med 2024;24(1):8-19.

Author Contributions

Conceptualization: Mehmet Muzaffer İslam, Merve Osoydan Satıcı, Serkan Emre Eroğlu.
Methodology and literature review: Mehmet Muzaffer İslam, Merve Osoydan Satıcı.
Writing ‑ original draft: Mehmet Muzaffer İslam, Merve Osoydan Satıcı, Serkan Emre Eroğlu.
Writing ‑review and editing: Mehmet Muzaffer İslam, Merve Osoydan Satıcı, Serkan Emre Eroğlu.
Visualization: Mehmet Muzaffer İslam.
Supervision: Mehmet Muzaffer İslam.
Project administration: Mehmet Muzaffer İslam.
Software: None.
Funding acquisition: None.
Resources: None.

Conflict of Interest

None Declared.

Financial Disclosure