Discussion
Coagulopathy becomes evident with increase in D-dimer and fibrinogen levels and minimal change in prothrombin time (PT), active partial thromboplastin time (aPTT) and platelet count 15. Hematological laboratory results can be used to determine the severity and prognosis of COVID-19 infection. Thrombocytopenia has been shown to be associated with an increased risk of severe disease and mortality associated with COVID-19 18. Platelet count has been accepted as a potential marker for COVID-19 since it is a simple, inexpensive and easily available hematological marker and since it is independent of disease severity and morbidity risk in the intensive care Unit 19.
In a study conducted on thrombocytopenia with patients with COVID-19,  mild thrombocytopenia was observed in approximately 5% of patients who had mild disease, thrombocytopenia was observed in 70-95% of patients who had severe disease 5-19. In a meta-analysis, when platelet count was compared, a significant difference was found between the COVID-19-negative group and the group that had severe COVID-19 in terms of platelet count and the individuals who had severe disease were found to have lower platelet count 18. In another study conducted on 1476 patients, a direct correlation was found in patients with COVID-19 between the decrease in platelet count and mortality 20. In another study conducted on patients with COVID-19, it was reported that low platelet count was associated with increased severe disease and death risk and it could serve as an indicator of worsening of the disease during the hospital stay in COVID-19 18. It has been reported that platelet count decreases significantly in patients with COVID-1921-22 and it is lower in patients who do not survive compared with those who survive 23.
Our study was found to be in parallel with the literature, a significant difference was found between groups and platelet count was found to be lower in the COVID-19 (+) group (U=5435.000, p=0.002, Effect size=0.20)(Table 2).
D-dimer is a fragment produced by the cleavage of fibrin by plasmin during clot breakdown 24. One of the most common laboratory findings in patients with COVID-19 who require hospitalization is the obvious elevation in D-dimer. A high D-dimer value has been reported as a poor prognostic marker associated with consistent critical course and higher mortality in patients with COVID-19 25-26. In a study conducted on 1099 patients with COVID-19 in China, high D-dimer levels were found in almost half of the patients 27.
In an observational study conducted on 183 patients in China, a statistically significant difference was found in the mean D-dimer concentration at admission between patients with COVID-19 who survived and those who did not 8. In another study conducted, patients with COVID-19 treated in ICU (Intensive Care Unit) were found to have higher D-dimer levels than patients with COVID-19 who were not treated in ICU 5. Finally, in another study involving 5279 patients with COVID-19, the COVID-19 (+) group was compared with the COVID-19 (-) group. The D-dimer level of the COVID-19 (+) group was found to be four times higher 28.
Our study was found to be consistent with the literature. The difference between groups was found to be significant. D-dimer levels were found to be higher in the COVID-19 (+) group, while they were found to be lower in the Covıd-19 (-) group (U=1457.500, p<0.001, Effect Size=0.69)(Table 2).
Among coagulation parameters, PT is another laboratory parameter with varying consequences in COVID-19. PT and aPTT are exogenous and endogenous coagulation system factors that can be used for the early diagnosis of DIC (Disseminated Intravascular Coagulation). In another observational study conducted on 183 patients in China, a mild prolongation was found in the mean PT concentration at admission between patients with COVID-19 who survived and those who did not and a statistically significant difference was found between the groups8. In another study conducted in China, the patients receiving treatment in ICU were found to have higher PT prolongation compared with patients who were not receiving treatment in ICU and a significant difference was found between the groups 5. In another study conducted on 187 patients diagnosed with COVID-19 and treated in the hospital, patients with high troponin-T level were found to have prolonged PT and aPTT levels 29. More pronounced prolongation of PT and APTT parameters indicates that patients are in a transition from high coagulation state to fibrinolytic state due to excessive coagulation factor consumption.
Our study was found to be consistent with the literature, a significant difference was found between the groups in terms of PT levels and prolongation was found to be higher in the PCR (+) Group (U=3765.500, p<0.001, Effect Size=0.40) (Table 2).
In conclusion, the relationship between PT, aPTT, DİMER, INR, PLT levels was evaluated according to COVID-19 results and gender. Our study showed statistical significance between groups in PT, D-dimer, INR, PLT values between PCR positive and negative groups in terms of especially COVID-19 results (p<0.01). It is important to find out coagulopathy and thrombocytopenia in Covid-19 patients. These parameters are also important biomarkers for the prognosis of the disease in COVID-19.
The results of this study have shown that hypercoagulation exists in patients with COVID-19 at an early stage and hypercoagulation is closely associated with disease progression and clinical outcome. For this reason, coagulation indicators such as D-dimer and PT should be monitored as early as possible to determine thrombotic complications. It is imperative to take preventive treatment to decrease thromboembolism and DIC risk secondary to coagulation disorder and thus to reduce the morbidity and mortality of patients infected with COVID-19.
Conflict of interest statement
There is no conflict of interest between the authors.