Special Focus

CBC Scoring of COVID-19 Inpatients May Help Hospitals Save Lives and Preserve Precious Treatment Resources

Early detection and early intervention have the potential to improve the prospects of recovery and positive outcomes for a broad range of diseases, including coronavirus. And now researchers in Europe believe they have found a method that uses a COVID-19 patient’s blood count to guide treatment and improve case outcomes. Here is an overview:

The Diagnostic Challenge

COVID-19 spans a wide clinical spectrum ranging from asymptomatic to severe pneumonia with multiple organ failure, and death. Early identification of critical patients requiring more aggressive intervention could go a long way in reducing COVID-19 deaths. But from almost the moment the pandemic began, the paramount objective of COVID-19 diagnostics has been to determine whether a person does or does not have the virus. Collecting information to guide medical treatment and improve clinical outcomes of patients who do have COVID-19 has received far less attention.

The initial emphasis on detection is understandable given how contagious the virus is and the fact that treatments for it remain largely unproven. However, as the crisis drags on and deepens, an increasing number of researchers have been delving into the treatment aspects of COVID-19 diagnostics.

The CBC Prognosis Test: Concept

One notable example of fruitful outcomes-based COVID-19 research is the recent study published by the journal eLife Sciences in December. The principal objective of the team of Dutch researchers sponsored by the Hamburg, Germany, subsidiary of the Japanese-based firm Sysmex, was to develop and validate a prognostic score using only hemocytometric data to predict a COVID-19 hospital patient’s risk of deterioration and need for transfer to intensive care unit (ICU). The risk score would be generated within the first three days of admission and assess the patient’s prognosis case over a period of 14 days to provide the opportunity for early intervention, if necessary, and objective risk stratification.

As the study authors note, COVID-19 has specific alterations in circulating blood cells that can be detected by a routine hematology analyzer, particularly in hematology analyzers that are capable of recognizing activated immune cells and early circulating blood cells. Accordingly, the team decided to base the test on a complete blood count (CBC) measuring the size, number and maturity of the different blood cells in a specific volume of blood, including:

  • Red blood cells, which are important for carrying oxygen and fighting anemia and fatigue. The hemoglobin portion of the CBC measures the oxygen carrying capacity of the red blood cells, while the hematocrit measures the percentage of red blood cells in the blood.
  • White blood cells, which fight infection. Increased numbers of white blood cells, therefore, may indicate the presence of an infection. Decreased levels may indicate certain rheumatic diseases or reaction to medication.
  • Platelets, which prevent the body from bleeding and bruising easily.

The scoring system incorporates a total of 10 parameters, including parameters for neutrophils, monocytes, red blood cells and immature granulocytes, and when available, reticulocyte and iron bioavailability measures.

The CBC Prognosis Test: Development

The research team developed the test using data from 982 adult patients presenting to a hospital from Feb. 21 to April 6, 2020, with outcomes followed until June 9. Among this cohort, only 7 percent were not admitted to a hospital; another 74 percent were admitted to a general ward and the remaining 19 percent were transferred directly to the ICU. The median age was 71 and approximately two-thirds of the cohort patients were male. The researchers used a Sysmex Europe GmbH XN-1000 hemocytometric analyzer to create an algorithm based on 1,587 CBC assays from 923 adults. They validated the scoring system in a second cohort of 217 CBC measurements in 202 people.

The Findings: The CBC score accurately predicted the need for critical care within 14 days in 70.5 percent of the development cohort and 72 percent of the validation group. The scoring system was superior to any of the 10 parameters alone. Over 14 days, the majority of those whom were classified as noncritical (NC) within the first three days of admission remained clinically stable, whereas the “clinical illness” (CI) group progressed, with clinical severity peaking on day 6.


A CBC-based scoring system that provides a reliable assessment of a COVID-19 inpatient’s prognosis over a 14-day period within the first three days of admission would surely be a huge help to hospitals right about now. In the context of the COVID-19 crisis, information about whether early intervention is necessary is crucial to not only medical treatment and outcomes but also preservation of ventilators and other tightly stretched hospital resources. Stated simply, hospitals need to be able to assess the risks faced by each COVID-19 inpatient and make timely and scientifically sound determinations about which patients are likely to recover without ventilators and which patients are likely to deteriorate resulting in the need for intensive care and risk of fatality.


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