Meta-Analysis
Copyright ©The Author(s) 2021. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Clin Infect Dis. Nov 5, 2021; 11(3): 49-59
Published online Nov 5, 2021. doi: 10.5495/wjcid.v11.i3.49
Lymphocyte count predicts the severity of COVID-19: Evidence from a meta-analysis
Yi-Si Zhao, Ying-Xi Yu
Yi-Si Zhao, Ying-Xi Yu, Department of Critical Care Medicine, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China
Author contributions: Zhao YS wrote and revised this manuscript; Zhao YS and Yu YX participated in discussion the research; Zhao YS searched and collected bibliography.
Conflict-of-interest statement: We not received any fees for serving as a speaker. We not received any research funding from.
PRISMA 2009 Checklist statement: The authors have read the PRISMA 2009 Checklist, and the manuscript was prepared and revised according to the PRISMA 2009 Checklist.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Yi-Si Zhao, MM, Doctor, Department of Critical Care Medicine, The First Affiliated Hospital of Chongqing Medical University, No. 1 Youyi road, Yuzhong District, Chongqing 400016, China. 476663973@qq.com
Received: February 27, 2021
Peer-review started: February 27, 2021
First decision: March 31, 2021
Revised: April 3, 2021
Accepted: September 10, 2021
Article in press: September 10, 2021
Published online: November 5, 2021
Processing time: 247 Days and 20.6 Hours
Abstract
BACKGROUND

In December 2019, coronavirus disease 2019 (COVID-19) was reported firstly in Wuhan, China. COVID-19 is currently a global pandemic.

AIM

To assess the suitability of lymphocyte count as a biomarker of COVID-19 severity.

METHODS

Five literature databases (PubMed/MEDLINE, Web of Science, Google Scholar, Embase, and Scopus) were searched to identify eligible articles. A meta-analysis was performed to calculate the standard mean difference (SMD) and 95% confidence interval (CI) of lymphocyte counts in coronaviral pneumonia cases.

RESULTS

Eight studies, including 1057 patients, were integrated in the meta-analysis. Lymphocyte counts were associated with severe coronavirus (CoV) infection (SMD = 1.35, 95%CI: 1.97 to 0.37, P < 0.001, I2 = 92.6%). In the subgroup analysis stratified by prognosis, lymphocytes were associated with CoV infection mortality (n = 2, SMD = 0.42, 95%CI: 0.66 to 0.19, P < 0.001, I2 = 0.0%), severity (n = 2, SMD = 0.93, 95%CI: 1.20 to 0.67, P < 0.001, I2 = 0.0%), and diagnostic rate (n = 4, SMD = 2.32, 95%CI: 3.60 to 1.04, P < 0.001, I2 = 91.2%).

CONCLUSION

Lymphocyte count may represent a simple, rapid, and commonly available laboratory index with which to diagnosis infection and predict the severity of CoV infections, including COVID-19.

Keywords: COVID-19; Lymphocyte count; Coronavirus; Severe of disease; Meta-analysis

Core tip: Lymphocyte count reflects immune function and inflammatory state in infectious disease. Severe acute respiratory syndrome coronavirus 2 spreads and invades through respiratory mucosa, triggers a series of immune responses and induces a cytokine storm, resulting in changes in immune components such as lymphocytes. Previous studies have shown that the decrease in lymphocyte count can be used as an indicator of severity for both severe acute respiratory syndrome and Middle East respiratory syndrome; both of which are coronavirus (CoV) infections. Therefore, this systematic review and meta-analysis evaluate the diagnostic and prognostic utility of the lymphocyte count in patients with viral pneumonia by CoV infections.