Hematological characteristics of patients in coronavirus 19 infection: a systematic review and meta-analysis

Background COVID-19 infection has become a pandemic and a global health issue since its origin in Wuhan, China in December 2019. The present systematic review and meta-analysis aim to assess hematological changes seen in COVID-19 infection and their association with the severity of the disease. Methods Pooled proportions were calculated using both fixed effects model and random effects model. Weighted mean difference and 95% CI were calculated and reported. Results Initial search identified 84 reference articles, 23 relevant articles were selected and reviewed. Compared to general population, the weighted mean difference of WBC count in all COVID-19 patients was lower by 0.97 × 10⁹ mm³ (95% CI = -1.29 to -0.66). In severe COVID-19 patients, the weighted mean difference of platelet count was lower by 23.85 × 10⁹/liter (95% CI = -35.18 to -9.53), as compared to general population. The weighted mean difference of prothrombin time, D-Dimer, and fibrinogen in severe COVID-19 patients was higher by 1.92 seconds (95% CI = 0.01 to 3.84), 6.23 mg/liter (95% CI = 0.11 to 12.36) and 1.88 g/liter (95% CI = 1.18 to 2.48) respectively, as compared to general population. Pooled proportion showed D-Dimer to be elevated in 80.00% (95 % CI = 50.00 to 99.00) of severe patients. Conclusions Our meta-analysis shows that patients with COVID-19 have significant thrombocytopenia, leukopenia along with elevated D-dimer, fibrinogen and prothrombin time. These laboratory findings are marked in severe COVID-19 infections and could be helpful in early recognition of severe infection.