Prognostic value of neutrophil-to-lymphocyte ratio in COVID-19 patients: A systematic review and meta-analysis

Juan R. Ulloque-Badaracco, W. Ivan Salas-Tello, Ali Al-kassab-Córdova, Esteban A. Alarcón-Braga, Jorge L. Maguiña*, Vicente Aleixandre Benites Zapata, Adrian Vladimir Hernández Diaz

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

37 Scopus citations


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.

OBJECTIVE: To evaluate the prognostic value of the NLR in patients diagnosed with COVID-19.

METHODS: We conducted a systematic review and meta-analysis. Observational studies that reported the association between baseline NLR values (ie, 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 (ORs) and their 95% confidence intervals (CIs). Small study effects were assessed with the Egger's test.

RESULTS: We analysed 61 studies (n = 15 522 patients), 58 cohorts, and 3 case-control studies. An increase of one unit of NLR was associated with higher odds of severity (OR 6.22; 95%CI 4.93 to 7.84; P < .001) and higher odds of all-cause mortality (OR 12.6; 95%CI 6.88 to 23.06; P < .001). In our sensitivity analysis, we found that 41 studies with low risk of bias and moderate heterogeneity (I 2 = 53% and 58%) maintained strong association between NLR values and both outcomes (severity: OR 5.36; 95% CI 4.45 to 6.45; P < .001; mortality: OR 10.42 95% CI 7.73 to 14.06; P = .005).

CONCLUSIONS: Higher values of NLR were associated with severity and all-cause mortality in hospitalised COVID-19 patients.

Original languageEnglish
Article numbere14596
Pages (from-to)e14596
JournalInternational Journal of Clinical Practice
Issue number11
StatePublished - Nov 2021


  • COVID-19
  • Humans
  • Lymphocytes
  • Neutrophils
  • Prognosis
  • SARS-CoV-2


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