This observational, case control study included 50 adult patients with positive COVID-19
PCR test recruited from isolation department of Mansoura university hospital from July
2021 to May 2022 as a study group, and control group included 25 healthy persons with no
history nor symptoms of COVID -19 and negative PCR test, matched with the study group
regarding the demographic variables and comorbidities.

The protocol of this study was approved by the Institutional Research Board of Faculty of
Medicine, Mansoura University (code no: MS.21.07.1596) and written informed consents were
obtained from all patients to be enrolled in this study.

The aim of this study was to evaluate platelet aggregation using light-transmission
aggregometry and adenosine diphosphate (ADP) as an agonist in COVID-19 patients, in
comparison to that in healthy controls.

Patients:

Inclusion criteria:

Age ≥ 18 years old.

Study group: COVID-19 confirmed cases with positive PCR test in the first week of
diagnosis with COVID-19 CT changes with any severity grade according to WHO, (2020) as:

Mild cases: mild clinical symptoms and no imaging findings of pneumonia. Moderate cases:
fever, respiratory symptoms and radiological abnormalities of COVID-19.

Severe cases: meet any of the following; SpO2 < 93%, PaO2 /FiO2 < 300, respiratory rate
equal or more than 30 breaths/min, or lung infiltration more than 50% including GGO or
consolidation .

Critically ill cases: respiratory failure, need for invasive MV, septic shock, and/or
multiorgan dysfunction.

Exclusion criteria:

The following patients were excluded:

Patients with thrombocytopenia and thrombocytosis defined as platelet count less than
100,000/ µL, count more than 450,000 / µL respectively Patients with hematocrit
abnormalities as less than 34% or greater than 55% Patients with disseminated
intravascular coagulation (DIC) Active malignancy Liver disease as such chronic
hepatitis, cirrhosis or liver cell failure. Any hematological disorders as hemophilia or
thalassemia. Patients on invasive mechanical ventilation as endotracheal intubation and
mechanical ventilation itself are factors for having a higher mean platelet volume (MPV)
which means that platelets are larger than average which are more adhesive and likely to
aggregate in vitro. Patients receiving aspirin, non-steroidal anti-inflammatory drugs,
antiplatelet drugs or any other medications that can influence platelet function (14 days
prior to blood sample collection)

Control group: healthy volunteers, persons with no history nor symptoms suggestive of
COVID-19 with negative COVID -19 PCR test and no CT Chest changes suggestive of COVID-19
infection. They were also matched with the study group in demographic variables and
comorbidities. Methods:

All patients were subjected to the following:

1. Full history taking with stress on: Demographic data (age and sex), smoking history
and co-morbid diseases as chronic obstructive pulmonary disease, hypertension,
diabetes mellitus, ischemic heart disease, bronchial asthma, cerebral stroke, and
malignancy. Symptoms suggestive of COVID-19 as dyspnea, cough, expectorations,
hemoptysis, fever, bone aches, sore throat, loss of taste, anosmia, diarrhea and
headache.

2. General and local chest examination.

3. Laboratory investigations as:

1. Complete blood count (CBC)

2. Liver function tests (ALT, AST, and serum albumin)

3. Serum creatinine • International normalized ratio (INR).

4. Inflammatory markers as (lactate dehydrogenase (LDH), C- reactive protein
(CRP), D-dimer and serum ferritin)

4. Radiological assessment (CT chest):

i. Description either consolidation or ground glass opacity according to Hansell et
al. (2008).

ii. CT severity score was assessed according to Bernheim et al. (2020) with each of
the five lung lobes assessed and scored for the degree of involvement and classified
as: score 0, no involvement (0% affected); 1, minimal (1%-25%); 2, mild (26%-50%);
3, moderate (51%-75%); and 4, severe (76%-100%). A total severity score was obtained
by summing the five lobe scores, with a range between 0 and 20. A score of 1-5 was
graded as "minimal," 6-10 as "mild," 11-15 as "moderate," and 16-20 as "severe."

5. Platelet aggregation work:

1. Reagent used: Adenosine diphosphate (ADP) was used in this study as an agonist
to enhance and evaluate platelet aggregation. It is a lyophilized preparation
of adenosine-5'-diphosphate. The working concentration of the reconstituted
reagent is 200 µM.

2. Device of aggregation: a platelet lighttransmission aggregometer (PAP-8E brand
aggregometer). It is manufactured by Bio/Data Corporation in USA, it has
programmable electronic pipette with charging stand, 8 test channels and
computer with monitor.

3. Test procedure was done according to Hvas and Favaloro (2017)

6. Outcomes measures:

1. Developing new thromboembolic event as arterial or venous thrombosis, such as
acute myocardial infarction (AMI), cerebral stroke, and pulmonary
thromboembolism during hospitalization and specifying the type of this event.

2. Need to invasive mechanical ventilation (MV).

3. Length of hospital stay (days) including more or less and equal 7 days.

4. Mortality rate.