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Neutrophil Lymphocyte Ratio and Platelet Lymphocyte Ratio as a Predictor of Mortality in Severe COVID 19 Cases
Corresponding Author(s) : Supriya P.S
International Journal of Allied Medical Sciences and Clinical Research,
Vol. 13 No. 2 (2025): 2025 Volume -13 - Issue 2
Abstract
Background: With the periodic recurrence of Covid-19 waves affecting millions, there was an urgent need to identify accessible biological markers that could predict disease severity and mortality early in the illness. Neutrophil-Lymphocyte Ratio (NLR) and Platelet-Lymphocyte Ratio (PLR) have been proposed as potential inflammatory indicators for this purpose.
Methods: A retrospective cohort study was conducted on 224 Covid-19 patients (August–October 2020). Patients were categorized into 'mild' and 'moderate to severe' groups. Mann-Whitney U and Chi-square tests were used for continuous and categorical variables, respectively. Receiver Operating Characteristic (ROC) analysis determined cut-off values for NLR, PLR, and age, along with sensitivity, specificity, and likelihood ratios.
Results: Age, hemoglobin, and NLR were significant predictors of disease severity, with NLR showing the strongest association. Cut-off value of NLR > 4.24 demonstrated high sensitivity (88.3%) and specificity (82.6%) for severe disease. Cut off value of PLR > 165.63 also showed good predictive value. An NLR > 6 indicated increased mortality risk. Among those with NLR > 10, mortality was notably higher in the severe group.
Conclusion: NLR and PLR are valuable, low-cost prognostic markers for assessing Covid-19 severity and mortality risk, particularly in low-resource settings. Their use can aid early intervention and treatment decisions.
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- Bulut C, Kato Y. Epidemiology of Covid - 19. Turk J Med Sci. 2020 Apr 21;50(SI-1):563-570. doi: 10.3906/sag-2004-172. PMID: 32299206; PMCID: PMC7195982.
- Aimrane A, Laaradia MA, Sereno D, et al. Insight into Covid - 19's epidemiology, pathology, and treatment. Heliyon. 2022 Jan;8(1):e08799. doi: 10.1016/j.heliyon.2022.e08799. Epub 2022 Jan 19. PMID: 35071819; PMCID: PMC8767941.
- Rathod BD, Amle D, et al. Neutrophil-to-Lymphocyte Ratio as a Predictor of Disease Severity and Mortality in Coronavirus Disease 2019: Prospective Study from Central India. Cureus. 2022 Mar 31;14(3):e23696. doi: 10.7759/cureus.23696. PMID: 35519791; PMCID: PMC9064266.
- National Clinical Management protocol Covid - 19 - Ministry of Health and family welfare. Government of India. Bulletin November 27, 2022.
- Zhou, F.; Yu, T.; Du, R.; et al. Clinical Course and Risk Factors for Mortality of Adult Inpatients with Covid - 19 in Wuhan, China: A Retrospective Cohort Study. Lancet 2020, 395, 1054–1062.
- Grasselli, G.; Zangrillo, A.; Zanella, A et al. Baseline Characteristics and Outcomes of 1591 Patients Infected With SARS-CoV-2 Admitted to ICUs of the Lombardy Region, Italy. JAMA 2020, 323, 1574.
- Khourssaji M, Chapelle V, Evenepoel A, et al. A biological profile for diagnosis and outcome of Covid - 19 patients.Clin Chem Lab Med. 2020;58:2141–2150
- Tang Y, Liu J, Zhang D, Xu Z, Ji J, Wen C.Cytokine storm in Covid - 19: the current evidence and treatment strategies. Front Immunol. 2020; 11:1–13
- Liao D, Zhou F, Luo L, et al.Haematological characteristics and risk factors in the classification and prognosis evaluation of Covid - 19: a retrospective cohort study. Lancet Haematol. 2020;7:0–8.
- Singh Y, Singh A, et al. Neutrophil-to-lymphocyte Ratio and Platelet-to-lymphocyte Ratio as Markers for Predicting the Severity in Covid - 19 Patients: A Prospective Observational Study. Indian J Crit Care Med. 2021 Aug;25(8):847-852. doi: 10.5005/jp-journals-10071-23906. PMID: 34733022; PMCID: PMC8559739.
- Ma A, Cheng J, Yang J, Dong M, et al. Neutrophil-to-lymphocyte ratio as a predictive biomarker for moderate-severe ARDS in severe Covid - 19 patients. Crit Care. 2020;24:1–4.
- Pirsalehi A, Salari S, Baghestani A, et al. Neutrophil-to-lymphocyte ratio (NLR) greater than 6.5 May reflect the progression of Covid - 19 towards an unfavorable clinical outcome. Iran J Microbiol. 2020;12(5):466–474. doi:10.18502/ijm.v12i5.4609.
- Tadesse Z, Bekele Bayissa A, Diriba T, et al. Neutrophil-to-Lymphocyte Ratio and Cut-off Values as Predictor of Severity and Mortality in Covid - 19 Patients in Millennium Covid - 19 Care Center, Addis Ababa, Ethiopia. Int J Gen Med. 2022;15:6739-6755.https://doi.org/10.2147/IJGM.S375565
- Yan X, Li F, Wang X, et al. Neutrophil to lymphocyte ratio as prognostic and predictive factor in patients with coronavirus disease 2019: a retrospective cross-sectional study. J Med Virol. 2020;92(11):2573–2581. doi:10.1002/jmv.26061.
- Citu C, Gorun F, Motoc A, et al. The Predictive Role of NLR, d-NLR, MLR, and SIRI in Covid - 19 mortality. Diagnostics. 2022;12(1):2–11. doi:10.3390/diagnostics12010122.
- Ma Y, Shi N, Fan Y. Predictive Value of the Neutrophil-to-Lymphocyte Ratio(NLR) for Diagnosis and Worse Clinical Course of the Covid - 19: Findings from Ten Provinces in China. The Lancet. 2020[Preprint]. doi:10.2139/ssrn.3569838.
- Pervaiz A, Pasha U, Bashir S, Arshad R, Waseem M, Qasim O. Original article neutrophil to lymphocyte ratio (Nlr) can be a predictor of the outcome and the need for mechanical ventilation in patients with Covid - 19 in Pakistan. Pak J Pathol. 2020;31(2):38–41
- Perera N, de Silva A, Kumbukage M, Rambukwella R, Indrakumar J. Neutrophil lymphocyte ratio as a marker of in-hospital deterioration in Covid - 19: observations from a resource constraint setting. Clin Pathol. 2022;15:2632010X2210908. doi:10.1177/2632010X221090898
References
Bulut C, Kato Y. Epidemiology of Covid - 19. Turk J Med Sci. 2020 Apr 21;50(SI-1):563-570. doi: 10.3906/sag-2004-172. PMID: 32299206; PMCID: PMC7195982.
Aimrane A, Laaradia MA, Sereno D, et al. Insight into Covid - 19's epidemiology, pathology, and treatment. Heliyon. 2022 Jan;8(1):e08799. doi: 10.1016/j.heliyon.2022.e08799. Epub 2022 Jan 19. PMID: 35071819; PMCID: PMC8767941.
Rathod BD, Amle D, et al. Neutrophil-to-Lymphocyte Ratio as a Predictor of Disease Severity and Mortality in Coronavirus Disease 2019: Prospective Study from Central India. Cureus. 2022 Mar 31;14(3):e23696. doi: 10.7759/cureus.23696. PMID: 35519791; PMCID: PMC9064266.
National Clinical Management protocol Covid - 19 - Ministry of Health and family welfare. Government of India. Bulletin November 27, 2022.
Zhou, F.; Yu, T.; Du, R.; et al. Clinical Course and Risk Factors for Mortality of Adult Inpatients with Covid - 19 in Wuhan, China: A Retrospective Cohort Study. Lancet 2020, 395, 1054–1062.
Grasselli, G.; Zangrillo, A.; Zanella, A et al. Baseline Characteristics and Outcomes of 1591 Patients Infected With SARS-CoV-2 Admitted to ICUs of the Lombardy Region, Italy. JAMA 2020, 323, 1574.
Khourssaji M, Chapelle V, Evenepoel A, et al. A biological profile for diagnosis and outcome of Covid - 19 patients.Clin Chem Lab Med. 2020;58:2141–2150
Tang Y, Liu J, Zhang D, Xu Z, Ji J, Wen C.Cytokine storm in Covid - 19: the current evidence and treatment strategies. Front Immunol. 2020; 11:1–13
Liao D, Zhou F, Luo L, et al.Haematological characteristics and risk factors in the classification and prognosis evaluation of Covid - 19: a retrospective cohort study. Lancet Haematol. 2020;7:0–8.
Singh Y, Singh A, et al. Neutrophil-to-lymphocyte Ratio and Platelet-to-lymphocyte Ratio as Markers for Predicting the Severity in Covid - 19 Patients: A Prospective Observational Study. Indian J Crit Care Med. 2021 Aug;25(8):847-852. doi: 10.5005/jp-journals-10071-23906. PMID: 34733022; PMCID: PMC8559739.
Ma A, Cheng J, Yang J, Dong M, et al. Neutrophil-to-lymphocyte ratio as a predictive biomarker for moderate-severe ARDS in severe Covid - 19 patients. Crit Care. 2020;24:1–4.
Pirsalehi A, Salari S, Baghestani A, et al. Neutrophil-to-lymphocyte ratio (NLR) greater than 6.5 May reflect the progression of Covid - 19 towards an unfavorable clinical outcome. Iran J Microbiol. 2020;12(5):466–474. doi:10.18502/ijm.v12i5.4609.
Tadesse Z, Bekele Bayissa A, Diriba T, et al. Neutrophil-to-Lymphocyte Ratio and Cut-off Values as Predictor of Severity and Mortality in Covid - 19 Patients in Millennium Covid - 19 Care Center, Addis Ababa, Ethiopia. Int J Gen Med. 2022;15:6739-6755.https://doi.org/10.2147/IJGM.S375565
Yan X, Li F, Wang X, et al. Neutrophil to lymphocyte ratio as prognostic and predictive factor in patients with coronavirus disease 2019: a retrospective cross-sectional study. J Med Virol. 2020;92(11):2573–2581. doi:10.1002/jmv.26061.
Citu C, Gorun F, Motoc A, et al. The Predictive Role of NLR, d-NLR, MLR, and SIRI in Covid - 19 mortality. Diagnostics. 2022;12(1):2–11. doi:10.3390/diagnostics12010122.
Ma Y, Shi N, Fan Y. Predictive Value of the Neutrophil-to-Lymphocyte Ratio(NLR) for Diagnosis and Worse Clinical Course of the Covid - 19: Findings from Ten Provinces in China. The Lancet. 2020[Preprint]. doi:10.2139/ssrn.3569838.
Pervaiz A, Pasha U, Bashir S, Arshad R, Waseem M, Qasim O. Original article neutrophil to lymphocyte ratio (Nlr) can be a predictor of the outcome and the need for mechanical ventilation in patients with Covid - 19 in Pakistan. Pak J Pathol. 2020;31(2):38–41
Perera N, de Silva A, Kumbukage M, Rambukwella R, Indrakumar J. Neutrophil lymphocyte ratio as a marker of in-hospital deterioration in Covid - 19: observations from a resource constraint setting. Clin Pathol. 2022;15:2632010X2210908. doi:10.1177/2632010X221090898