Hematological Changes in Patients with Severe COVID-19: Systematic Review and Meta-Analysis

Aims: To produce a systematic review with meta-analysis on the hematological manifestations of COVID-19, comparing the changes among the clinical severity groups.

Study Design: We conducted a systematic review with meta-analyses.

Methodology: A systematic review was carried out based on the PRISMA 2020 protocol in Medline/Pubmed, Embase, LILACS and SciElo databases. A standardized mean difference was calculated to assess the differences between the groups, with a confidence interval of 95%. Heterogeneity was calculated using the Chi-square test and the I2 test. Significant heterogeneity was defined as p<0.10 or I2>50%.

Results: The systematic review search identified a total of 2682 articles, and at the end of the screening, 55 were selected for review and 16 for meta-analysis. The selected articles enrolled 13,289 participants, 10,312 with a mild to moderate clinical condition and 3977 with a severe to critical clinical condition. When comparing the severe disease group with the mild disease group, it was found that the mean values of leukocytes, neutrophils, C-reactive protein (CRP), ferritin, fibrinogen, and prothrombin time (PT) were significantly higher, and the lymphocyte count was significantly lower in the severe group.

Conclusions: Individuals with severe COVID-19 had reduced lymphocyte count and elevated leukocytes, neutrophils, CRP, ferritin, fibrinogen, and PT.