Objective Clinical and laboratory biomarkers to predict the severity of coronavirus disease 2019 (COVID-19) are essential in this pandemic situation of which resource allocation must be urgently prepared especially in the context of respiratory support readiness. Lymphocyte count has been a marker of interest since the first COVID-19 publication. We conducted a systematic review and meta-analysis in order to investigate the association of lymphocyte count on admission and the severity of COVID-19. We would also like to analyze whether patient characteristics such as age and comorbidities affect the relationship between lymphocyte count and COVID-19. Methods Comprehensive and systematic literature search was performed from PubMed, SCOPUS, EuropePMC, ProQuest, Cochrane Central Databases, and Google Scholar. Research articles in adult patients diagnosed with COVID-19 with information on lymphocyte count and several outcomes of interest, including mortality, acute respiratory distress syndrome (ARDS), intensive care unit (ICU) care, and severe COVID-19, were included in the analysis. Inverse variance method was used to obtain mean differences and its standard deviations. Maentel-Haenszel formula was used to calculate dichotomous variables to obtain odds ratios (ORs) along with its 95% confidence intervals. Random-effect models were used for meta-analysis regardless of heterogeneity. Restricted-maximum likelihood random-effects meta-regression was performed for age, gender, cardiac comorbidity, hypertension, diabetes mellitus, COPD, and smoking. Results There were a total of 3099 patients from 24 studies. Meta-analysis showed that patients with poor outcome have a lower lymphocyte count (mean difference − 361.06 μL [− 439.18, − 282.95], p < 0.001; I 2 84%) compared to those with good outcome. Subgroup analysis showed lower lymphocyte count in patients who died (mean difference − 395.35 μL [− 165.64, − 625.07], p < 0.001; I 2 87%), experienced ARDS (mean difference − 377.56 μL [− 271.89, − 483.22], p < 0.001; I 2 0%), received ICU care (mean difference − 376.53 μL [− 682.84, − 70.22], p = 0.02; I 2 89%), and have severe COVID-19 (mean difference − 353.34 μL [− 250.94, − 455.73], p < 0.001; I 2 85%). Lymphopenia was associated with severe COVID-19 (OR 3.70 [2.44, 5.63], p < 0.001; I 2 40%). Meta-regression showed that the association between lymphocyte count and composite poor outcome was affected by age ( p = 0.034). Conclusion This meta-analysis showed that lymphopenia on admission was associated with poor outcome in patients with COVID-19.
【저자키워드】 COVID-19, SARS-CoV-2, coronavirus, lymphopenia, Lymphocyte count, 【초록키워드】 coronavirus disease, Meta-analysis, ARDS, pandemic, Mortality, intensive care, severe COVID-19, severity, Diabetes Mellitus, systematic review, Comorbidity, Gender, outcome, smoking, hypertension, heterogeneity, meta-regression, ICU, COPD, databases, Characteristics, severity of COVID-19, clinical, Patient, age, information, resource, Admission, Care, predict, association, acute respiratory distress, marker, Analysis, Odds ratio, Respiratory Support, Google Scholar, Confidence intervals, ICU care, standard deviations, syndrome, mean difference, article, systematic literature search, ProQuest, Affect, objective, likelihood, inverse, Comprehensive, Result, affected, was used, died, conducted, was performed, were used, calculate, diagnosed with COVID-19, dichotomous variable, laboratory biomarker, patients with COVID-19, random-effect, 【제목키워드】 Meta-analysis, systematic review,