European Journal of Cardiovascular Medicine

COVID-19 disease, which is a global pandemic, is predominantly caused by SARS-CoV-2 virus. This virus belongs to beta-coronavirus 2b lineage, a new strain of RNA viruses which has not been identified in humans previously⁽¹⁾. COVID-19 disease predominantly affects the respiratory system, other organs can also be involved. Some of the patients have favourable outcome, but few of the patients progress to critical stages with severe respiratory distress syndrome, coagulation dysfunction and multiple organ failure⁽²‘³⁾.The case-fatality rate for COVID-19 is 2.3% but for patients aged 70-79 years is 8.0% and 80 years and above is 14.8%⁽⁴⁾. It is accompanied by various biochemical and cellular changes including leukocytosis, leukopenia, neutrophilia, hypoalbuminemia, hyperglycemia, etc⁽⁵‘⁶⁾. The critically ill patients particularly those requiring ICU admission have high probability of developing hypercoagulability. According to one of the study reports the higher neutrophil-to-lymphocyte ratio is associated with greater incidence of venous thromboembolism⁽⁷⁾. All of the coagulation profile including activated partial thromboplastin time, prothrombin time, fibrinogen, fibrin, etc can be derranged by covid-19 and there can be contrasting variations in the laboratory results of various patients with the severity of the disease⁽⁸⁾. The outbreak of  the  coronavirus  disease  can be managed efficiently  by determining the early and effective predictors of clinical outcomes. This study seeks to determine the utility of D-dimer and prothrombin time as a biomarker to predict the outcomes in covid-19 patients by determining the disease severity and prognosis.

This was a retrospective study done in the Government Medical College, Kathua .In this study only those patients were included who were admitted in the hospital premises. In GMC Kathua, for COVID-19 diseased patients, Isolation wards were made where in moderately ill patients were admitted and 24 hr ICU was kept for severely ill patients with severe disease complications. The study included the RT-PCR positive patients from isolation ward and ICU who were moderately to severely sick and those were admitted over a period of 6 months from 1st January to 30th June2021. The RT-PCR negative cases and asymptomatic and mild symptomatic diseased patients were not included in the study. The COVID-19 patient has been classified into 3 types by the AIIMS, New Delhi guidelines: Mild disease: Upper Respiratory tract symptoms (&/or fever) without shortness of breath or hypoxia. Moderate disease: Any one of: (1) Respiratory rate>/=24/min (2) Spo2 </=93% on room air -Severe disease : Any one of: (1) Respiratory rate>30/min 2)Spo2<90% on room air According to these guidelines; patients with Mild disease require only home isolation along with the prescribed medications. The patients with moderate disease have to be admitted in wards and discharged only after improvement whereas the patients with severe disease needs to be admitted in ICU. These patients can be discharged after clinical improvement as per the discharge criteria. So, the D-dimer and prothrombin levels of these admitted patients who were moderately to severely ill were sent in the clinical pathology section of Department of Pathology and were studied. D-DIMER: The d-dimer kit used in our hospital is Erba D-Dimer R which is an immunoturbidimetric assay used for the quantitative determination of the fibrin degradation products that contain D-dimer in human plasma. Clinical Significance: D-dimer containing moieties are formed by plasmin degradation of factor XIlla cross-linked fibrin. Elevated levels of D-dimer are found in clinical conditions such as deep vein thrombosis (DVT), pulmonary embolism (PE) and disseminated intravascular coagulation (DIC)⁽⁹‘ͬ¹⁰‘¹¹⁾, Laboratory measurements of fibrin degradation products, including D-dimer, have significance in the assessment of these conditions. Principle: Erba D-Dimer R is a turbidimetric assay that utilises antibody coated latex particles. In the presence of D-dimer, the particles aggregate and turbidity increases. The increase in scattered light is proportional to the amount of D-dimer in the sample. The latex particles are coated with a monoclonal antibody that reacts with fibrin D-dimer or fragment D of fibrin. The antibody has no cross reactivity with fibrinogen⁽¹²⁾. This allows for the determination of D-dimer in human plasma. Composition: Important: The reagents are lot-specific. Lots are not interchangeable. R1-D-Dimer Buffer: containing buffer and preservatives R2-D-Dimer Latex: latex particle coated with anti-D-Dimer monoclonal antibody. Working Reagent: Reagents are ready to use. Avoid reagents contamination. The Latex (R2) may sediment during storage. Mix thoroughly before use. Stability and storage: The unopened reagents are stable till the expiry date stated on the bottle and kit label when stored at 2-8°C R1-Buffer opened vials are stable: 4 weeks at 2-8°C 2 weeks at 20°C Procedure - Add 75ul of R1 in a cuvette. - After about 60 seconds, add 15ul of plasma of patient and mix properly with formation of froth. - Add 60ul of R2 but no mixing at this step should be done - The machine takes about 150-200seconds to give the reading. - The reading is multiplied by 2.5 to get value o D-dimer in ng/ml. Prothrombin Time: The prothrombin time kit used in our hospital is Erba Protime LS. Principle: The one-stage PT measures the clotting time of plasma after adding a source of tissue factor(thromboplastin) and calcium. The recalcification of plasma in the presence of tissue factor generates activated factor Xa. Factor Xa in turn activates prothrombin to thrombin,which converts fibrinogen to an insoluble fibrin clot.⁽¹³‘¹⁴⁾ The time of this clotting process is measurable manually or with optical or mechanical coagulation analysers. Composition: Erba Protime LS is a tissue thromboplastin from rabbit brain,which converts calcium ions and sodium azide(<0.01%)as preservative. Procedure: Plastic or siliconised glass should be used throughout.Blood (9parts)should be collected into 3.2% or 3.8% sodium citrate anticoagulant(1part).Separate plasma after centrifugation at 1500 x g for 15 minutes. Plasma should be kept at 18-24⁰C. Testing should be completed within 4 hours of sample collection,or plasma can be stored frozen at -20⁰c for 2 weeks or -70⁰c for 6 months. Thaw quickly at 37⁰C prior to testing. Donot keep at 37⁰C for more than 5 minutes.⁽¹⁵⁾ Manual Method - Mix sufficient Erba Protime LS reagent to complete the anticipated testing for the day and incubate reagent at 37⁰C no more than 4 hours. - Add 50ul of patient plasma or control plasma into a reaction tube and incubate at 37⁰C for 2 minutes. - Add 100ul of freshly mixed reagent and start simultaneously a timer. - Note the time for clot formation nearest 0.1 seconds. Automated Method In this method machine automatically gives reading within 15-20 seconds and no need of a timer.

1. Demographic characteristics: Out of 115 COVID-19 patients studied, about 65 cases (56.5%) were males and 50 cases (43.4%) were females. Moreover, majority of the patients were between the age group of 61-80 years that is 44 cases out of 115 (38.2%).Table 1 and Table 2 shows the complete data and according to this study, majority of the patients were males and more patients were above 60 years that is consistent with the previous literature report.

TABLE 1: Sex Distribution of COVID-19 patients

TABLE 2: Age Distribution of COVID-19 patients

2. Classification of COVID-19 patients: The COVID-19 patients were clinically classified according to symptoms, sPO₂ and respiratory rate into mild, moderate and severe cases. The admitted cases in the hospital were either moderate or severe cases only. The mild cases were given treatment with home isolation.

TABLE 3: Classification of COVID-19 cases:

According to our study,about 90 cases out of 115 cases (78.2%) were classified as severe cases and 25 cases out of 115 cases(21.7%) were classified as moderate cases as shown in table 3. Both moderate and severe cases showed male predominance which is consistent with the previous literature report.

3.Effect of dynamic changes of D-Dimer and Prothrombin Time on outcome of COVID-19 patients: D-dimer and Prothrombin Time values of moderate and severe cases were observed and about 30 of the 90 severe cases showed raised D-Dimer levels(33.3%) and 28 of the 90 severe cases showed raised raised Prothrombin time levels(31.1%). However, 5 of the 25 moderate cases showed raised D-Dimer levels(20%) and 3 of the 25 moderate cases showed raised Prothrombin levels(12%) as described in detail in table 4.

The outcome was followed in these patients that showed total 35 death cases(30.4%)out of 115 cases. Of these 30 deaths were of severe cases(33.3%) and 5 death cases  were of moderate cases(20%) . The rest 80 cases(69.5%) were discharged with or without morbidity as described in detail in table 5.

TABLE 4: D-Dimer and Prothrombin Time values of COVID-19 patients:

TABLE 5: OUTCOME OF COVID-19 CASES:

The results of this study showed that COVID-19 patients have a hypercoaguable state at an early stage that is directly related to the outcome of the disease and its progression to various complications.The total 35 deaths that occurred in covid patients were the patients with raised levels of both D-Dimer and Prothrombin time. Rest of the patients were discharged either with  or without morbidity. Therefore, the coagulation indicators like D-DIMER and PROTHROMBIN TIME should be assessed at an early stage to detect and avoid the thrombotic complications. This will also help the clinicians to start preventive treatment for thromboembolism and DIC that occur secondary to coagulation disorder, thereby reducing the morbidity and mortality of the COVID-19 patients.

Financial Support and Sponsorship: Nil

Conflicts of Interest: There are no conflicts of interest.