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Meta-Analysis
. 2021 Nov;75(11):e14596.
doi: 10.1111/ijcp.14596. Epub 2021 Jul 27.

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

Juan R Ulloque-Badaracco  1 , W Ivan Salas-Tello  1 , Ali Al-Kassab-Córdova  1 , Esteban A Alarcón-Braga  1 , Vicente A Benites-Zapata  2 , Jorge L Maguiña  1   3 , Adrian V Hernandez  4   5
Affiliations
Meta-Analysis

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

Juan R Ulloque-Badaracco et al. Int J Clin Pract. 2021 Nov.

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.

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 (I2 = 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.

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Conflict of interest statement

Authors declare no conflict of interest.

Figures

FIGURE 1
FIGURE 1
PRISMA 2009 flow diagram
FIGURE 2
FIGURE 2
(A) Association of NLR and COVID‐19 severity. (B) Subgroup analysis according to study design of the association between NLR and severity in COVID‐19 patients. (C) Subgroup analysis according to the origin country of the association between NLR and severity in COVID‐19 patients. (D) Sensitivity analysis according to risk of bias of the association between NLR and severity in COVID‐19 patients
FIGURE 3
FIGURE 3
(A) Association between NLR and mortality in COVID‐19 patients. (B) Subgroup analysis according to the origin country of the association between NLR and mortality in COVID‐19 patients. (C) Subgroup analysis according to study design of the association between NLR and mortality in COVID‐19 patients. (D) Sensitivity analysis according to risk of bias of the association between NLR and mortality in COVID‐19 patients
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