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Prognostic value of Neutrophil-to-lymphocyte ratio in COVID-19 patients: A systematic review and meta-analysis
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  • Juan R. Ulloque-Badaracco,
  • Ivan Salas-Tello,
  • Ali Al-kassab-Cordova,
  • Esteban A. Alarcon-Braga,
  • Vicente Benites-Zapata,
  • Jorge Maguiña,
  • Adrian V. Hernandez
Juan R. Ulloque-Badaracco
Universidad Peruana de Ciencias Aplicadas
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Ivan Salas-Tello
Universidad Peruana de Ciencias Aplicadas
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Ali Al-kassab-Cordova
Universidad Peruana de Ciencias Aplicadas
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Esteban A. Alarcon-Braga
Universidad Peruana de Ciencias Aplicadas
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Vicente Benites-Zapata
Universidad San Ignacio de Loyola
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Jorge Maguiña
Universidad Peruana de Ciencias Aplicadas
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Adrian V. Hernandez
Universidad San Ignacio de Loyola
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Abstract

Background: Neutrophil-to-lymphocyte ratio (NLR) is an accessible and widely used biomarker. NLR may be used as an early marker of poor prognosis in patients with COVID-19. Methods: We conducted a systematic review and meta-analysis. Observational studies that reported the association between baseline NLR values (i.e. at hospital admission) and severity or all-cause mortality in COVID-19 patients were included. The quality of the studies was assessed using the Newcastle-Ottawa scale (NOS). Random effects models and inverse variance method were used for meta-analyses. The effects were expressed as odds ratios (OR) and their 95% confidence intervals (CI). Small study effects were assessed with the Egger’s test. Results: Twenty studies, 19 cohorts and one case-control were included. An increase of one unit of NLR was associated with a higher odds of COVID-19 severity (OR 6.6, 95% CI: 4.71 - 7.19; p<0.001) and higher odds of all-cause mortality (OR 12.7, 95% CI: 1.32, 123.36; p=0.025). No differences were found in subgroup analyses by study design. The subgroup analysis of the studies, by country of origin, showed that the strength of the association between NLR and mortality was greater in Chinese studies (OR 31.1; 95%CI 19.57 to 49.3; p<0.0001) with moderate heterogeneity (I2 =43%). In our sensitivity analysis, we found that 7 studies with low risk of bias maintained strong association between both outcomes and the NLR values (severity: OR 4.7; 95% CI 3.5 to 6.34; p < 0.001 vs mortality: OR 31.1; 95% CI 19.57 to 49.3; p <0.0001), with low (I2 = 37%) and moderate (I2 = 43%) heterogeneity for severity and mortality outcomes, respectively. No publication bias was found for studies that evaluated effects for the severity of disease. Conclusions: Higher values of NLR were associated with severity and all-cause mortality in hospitalized COVID-19 patients.

Peer review status:UNDER REVIEW

24 Jan 2021Submitted to International Journal of Clinical Practice
25 Jan 2021Submission Checks Completed
25 Jan 2021Assigned to Editor
01 Feb 2021Reviewer(s) Assigned
10 Apr 2021Review(s) Completed, Editorial Evaluation Pending
25 May 20211st Revision Received
08 Jun 2021Submission Checks Completed
08 Jun 2021Assigned to Editor
08 Jun 2021Review(s) Completed, Editorial Evaluation Pending
09 Jun 2021Reviewer(s) Assigned