In this study there was an obvious association noted between ABO blood type and the severity of COVID-19 pneumonia known by calculation of the CT-SS, as we found that there is a strong correlation between the patients with blood group A and the more severe pneumonic process in their non-contrast high resolution CT chest with relatively higher severity score, compared to the other patients with other blood group.
On the other hand, patients with blood group O were found to be relatively protected with less severity of CT findings and less CT-SS which is considered as a mirror to the overall severity of the disease. Most of the other studies correlated the ABO blood group with the susceptibility to the COVID-19 infection rather than the severity of the disease.
However, few articles studied the association between the blood type and the severity of the clinical symptoms of the disease and not with the CT severity scoring system. We found that the patients with blood group A were prone to higher CT severity score and consequently increased risk of morbidity and mortality compared to other blood groups.
The CT-SS was created as a semi-quantitative method to assess COVID-19 burden on the initial CT scan obtained at admission and provide an approach to identify patients in need of hospital admission . The (CT-SS) is a modification of a method used during the SARS epidemic of 2005 . Both lungs were divided into five lobes, and each lobe was assessed individually. The abnormalities that were considered significant for the disease included the following: ground-glass opacity, consolidation, reticulation, crazy-paving pattern, nodule, interlobular septal thickening, linear opacities, subpleural curvilinear line and/or bronchial wall thickening.
Kibler et al., studied the risk and severity of COVID-19 and ABO blood group in Transcatheter aortic valve patients and found that, in these patients the subgroup with the A blood type was especially prone to develop the disease and showed unfavorable outcomes .
Zhao et al. in the Wuhan experience evaluated the association between blood type and susceptibility to COVID-19 infection and found that blood group A was associated with a higher risk for acquiring COVID-19 compared with non-A blood groups, whereas blood group O was associated with a lower risk for the infection compared with non-O blood groups .
Latz et al., studied the relation between blood groups and the severity of the COVID-19 disease that defined as patient intubation or death and was found that, blood type is not associated with risk of progression to severe disease requiring intubation or causing death, nor is it associated with higher peak levels of inflammatory markers .
Liu et al., also evaluated the impact of ABO blood group on COVID-19 infection risk and mortality and found that blood groups A and B may be risk factors for COVID-19 with possible unfavorable outcomes in the group A patients, whereas the blood group O appears to be protective .
In our study, we used the CT-SS as a semiquantitative measure to assess the severity of the COVID-19 disease and its impact on the lungs in Egyptian patients and the mean CT-SS was 9.9.
In 2020, Hafez studied the mean CT-SS and its correlation with chest manifestations in Egyptian patients with COVID-2019 pneumonia and stated that the assessment of the CT severity score of COVID-19 is essential for the extent of pneumonia to allow early diagnosis and accurate treatment and found that the mean CT-SS was 11.2 .
In February 2020, Yang et al., also used the CT-SS as a tool to assess the severity of COVID-19 pneumonia and found that CT-SS could be potentially used to expedite triage of patients in need of hospital admission .
We think that the CT severity scoring may help the clinician in their management of COVID-19 infection, hand by hand with the clinical severity scoring dealing with different aspect of clinical data of the patients including heart rate, blood pressure, temperature, performance, age, sex respiratory rate, O2 saturation, and alertness.