Crucial Laboratory Parameters in Severe COVID-19 Infection: A Systematic Review and Meta-Analysis

Aim: Abnormal laboratory findings have been shown to be associated with severe COVID-19. However, all aspects of this association have not been reviewed systematically. Therefore, the aim of this meta-analysis was to explore crucial laboratory parameters in severe COVID-19 infection. Methods: We performed the literature review of scientific articles indexed in electronic databases. Scientific search engines were used to perform the electronic literature search. After the removal of duplicates and selection of articles of interest, 30 studies were eligible to include. If heterogeneity was high (I²>50%), a random-effects model was applied to combine the data. Otherwise, a fixed-effects model was used.Results: A total of 5586 individuals were assessed (1555 patients with severe COVID-19 infection and 3452 with non-severe infection). Platelets, lymphocytes and serum albumin were significantly lower in severe patients while other biochemical and immunological parameters including prothrombin time, ALT, AST, total bilirubin, LDH, procalcitonin, CRP, IL-6, and IgA were significantly higher in patients with severe infection. Neutrophil and monocyte counts as well as hemoglobin level, D-dimer, hypersensitive troponin I, IL-2R, IgG and IgM levels were different between two groups; however, the difference was not statistically significant (All P-values >0.05). Conclusions: Lymphopenia, elevated liver enzymes, and high levels of inflammatory biomarkers are associated with severe COVID-19 infection.