Laboratory tests

Abstract

Background The lack of awareness of COVID-19 severity in the early stages of the disease has led to a dramatic increase in the number of patients worldwide. A cost-effective, easily acquired biomarker is needed to classify disease severity at early stages. Objective The objective of this paper is to explore the role of basic laboratory tests in the classification of COVID-19 patients into different severity groups. Methods Socio-demographic data, including age and gender together with laboratory investigations, including complete blood count, CRP, serum D-dimer, ferritin, LDH, and liver function tests were collected during the period from November 2020 to January 2021 from the medical records of 100 adult COVID-19 patients admitted at the Quarantine Hospitals of Ain-Shams University. Results The present study included 100 COVID-19 patients (51 females and 49 males) with a mean age of 57±15.74 years. They were 27 mild, 40 moderate, and 33 severe. The disease severity could not be linked to a specific gender; however, the severity increased with advanced age. CBC results showed no significant differences in total leucocytic counts, hemoglobin levels, or platelet counts; however, the absolute lymphocyte counts decreased significantly as the disease worsened. Also, in more severe disease, there was a highly significant increase in ferritin, D-dimer, LDH, and CRP levels with no significant differences in ferritin and LDH levels between moderate and severe groups. On the other hand, AST and ALT levels showed no significant differences between the three groups. Significant negative correlations were found between absolute lymphocyte count and ferritin, D-dimer, and CRP levels. By ROC curve, a cut-off point for absolute lymphocyte count of less than or equal to 1.5×103/cmm, D-dimer of greater than 0.78 mg/l, and CRP of greater than 56 mg/l were used to differentiate mild and moderate cases, and a cut-off point for absolute lymphocyte count of less than or equal to 1.06×03/cmm, D-dimer of greater than 1.58 mg/l, and CRP of greater than 78 mg/l were used to differentiate moderate and severe cases. Furthermore, the kappa statistic test found a moderate degree of agreement between the existing guideline for disease typing, and absolute lymphocyte count, D-dimer, and CRP levels. Conclusion This study suggested that incorporation of laboratory variables including absolute lymphocyte count, D-dimer, and CRP into the existing guideline for disease typing, may be of value for quick cost-effective identification of potentially critically ill patients at an early stage of the disease.