Peripheral Blood Film as a Tool to Assess Severity of Coronavirus Disease 2019 – A Single-Center Study in Saudi Arabia

Background: On December 31, 2019, infection by Coronavirus Disease 2019 (COVID-19) was reported in China, and that turned out to be a pandemic after that. Complete blood count (CBC) and inflammatory markers are important parameters in the disease progression and prognosis. We are conducting this study to determine the usefulness of peripheral blood film (PBF) as a laboratory tool to assess the severity of COVID-19. Methods: We are conducting a retrospective, observational study in a Tertiary Care Hospital. Around 85 patients admitted to the hospital between July and August 2020 those diagnosed with COVID-19-positive infection, were enrolled in this study. All adults (≥18 years old) admitted to the hospital who are affected by COVID-19 were eligible for the study. Historical data including demographic features, laboratory tests including CBC with indicators of the disease severity as D-dimer, ferritin, C-reactive protein (CRP), and lactate dehydrogenase, in Addison to the PBF as well as outcome were assessed and comparisons run in the setting of intensive care unit (ICU) and non-ICU groups. Results: The mean age for the ICU and non-ICU patients was significant (63.6 years and 53.9 years, respectively, P < 0.01). Moreover, hypertension (P = 0.04), liver disease (P < 0.01), as well as, the need for intubation and mortality were significantly higher in ICU group (P < 0.01). The mean value of the neutrophils and lymphocyte count between ICU and non-ICU groups was 5.47 vs. 4.23 and 1.17 vs. 1.26, respectively. Atypical lymphocytes were statically insignificant between ICU and non-ICU candidates (P = 0.33). Furthermore, PBF findings showed significantly higher white blood cell (WBCs) distribution with higher neutrophils in the ICU group (P < 0.01 and P < 0.02 respectively), the corresponding empirical receiver operating characteristic curve was drawn for WBC and the area under the curve = 0.7 for WBC (P < 0.05). Conclusion: Although PBF showed a significant increase in the total WBC mainly neutrophils distribution in critically ill patients, there was no significant correlation between PBF and intubation or outcome