Crucial laboratory parameters in COVID-19 diagnosis and prognosis: An updated meta-analysis.

Introduction And Objectives: Common laboratory parameters are crucial in aiding coronavirus disease 2019 (COVID-19) case detection. This study aimed to determine the differences between laboratory parameters in (1) COVID-19 versus non-COVID-19 pneumonia, and (2) severe versus non-severe COVID-19 cases.

Methods: Studies were collected until March 2020, and retrieved parameters include leukocyte, neutrophil, thrombocyte, and lymphocyte counts in addition to C-reactive protein (CRP), procalcitonin (PCT) and D-dimer levels. In the presence of heterogeneity, the random-effect model (REM) was used instead of the fixed-effect model (FEM).

Results: Seven studies in the first analysis showed significantly lower leukocyte, neutrophil and platelet counts in COVID-19 pneumonia (SMD = -0.42, 95%CI -0.60 to -0.25,  < 0.00001, SMD = -0.23, 95%CI -0.41 to -0.06,  = 0.01, SMD = -0.54, 95%CI -0.91 to -0.16,  = 0.0005) compared to non-COVID-19 pneumonia. Twenty-six studies in the second analysis showed significantly lower lymphocyte and thrombocyte counts (SMD = -0.56, 95%CI -0.71 to -0.40,  < 0.0001, SMD = -0.32, 95%CI -0.49 to -0.15,  = 0.0002) and significantly higher leukocyte, neutrophil, D-dimer, and CRP (SMD = 0.31, 95%CI 0.07-0.56,  = 0.01; SMD = 0.44, 95%CI 0.24-0.64,  < 0.0001; SMD = 0.53, 95%CI 0.31-0.75,  < 0.00001; SMD = 0.97, 95%CI 0.70-1.24,  < 0.00001) in severe COVID-19 compared to non-severe COVID-19.

Conclusions: In conclusion, thrombocyte count is key in both diagnosis and prognosis. Low leukocyte and neutrophil counts are markers of COVID-19 infection, but contrastingly higher counts indicate progressive COVID-19. And although lymphocyte, D-dimer and CRP levels did not demonstrate diagnostic value, all indicate severity of COVID-19. Confirmation of these findings should be performed in future studies.