In this study, the D-dimer levels correlate with COVID-19 patients as a reliable prognostic marker. Notably, there was a higher tendency to have an intravascular coagulopathy in the COVID-19 patients as the Odds Ratio was 3.949, p < 0.001 for COVID-19 patients with high D-dimer > 500 ng/ml. Indeed, COVID-19 infections increased the D-dimer average level to six times higher than the non-infected samples. The relationship between D-dimer and COVID-19 infection is particularly important in severe cases, where elevated levels of D-dimer can contribute to the development of venous thromboembolism and other clotting disorders[18–20]. In this regard, a previous report demonstrates that patients with COVID-19 frequently have increased fibrinogen. Further, data revealed that in COVID-19 patients, high levels of fibrinogen are correlated with severe illness, exaggerated inflammation, and ICU hospitalization [21]. Additional recent research has demonstrated the significance of using inflammatory markers, such as serum ferritin and D-dimer, to predict the prognosis of COVID-19 patients. These markers have a strong correlation with disease mortality, ICU admission, and the requirement for mechanical ventilation, all of which aid in the early identification of case risk of progression and, ultimately, improve outcomes [22, 23]. Interestingly, Aydin and Golcuk found that the third and fourth months of the post-COVID-19 period had the highest rate of D-dimer increase [24].
Significant correlation between COVID-19 and age group was also demonstrated. In comparison to younger individuals, older populations were more likely to experience unfavorable consequences. Healthcare providers ought to focus mostly on patients in that risk category [25]. However, a previous report from India demonstrated that the most vulnerable age group was 21–30 years[26]. This could be related to the fact that this group represents the most active worker group even during the pandemic lockdown. Likewise, age can be an indirectly influential variable that affects D-dimer levels, according to our previous findings that have been evaluated in our lab (Aburayyan, 2023 unpublished data). In this context, the study population's odds ratio for age on D-dimer levels was 1.579. This means that an increased risk of expressing one of the coagulation events such as Deep Vein Thrombosis (DVT), pulmonary embolism, or heart attack will raise the release of fibrin degradation products as the bloodstream's D-dimer level rises. Other age-related conditions, such as renal function impairment because of aging, may also have an indirect impact on D-dimer levels. The kidneys are responsible for reducing D-dimer from the blood [27]. This indicates that D-dimer levels may have a minor propensity to rise with aging. However, the effects of aging on D-dimer levels are multifaceted and can be influenced by a range of factors, such as lifestyle decisions and underlying medical disorders. In a previous study (Aburayyan, 2023 unpublished data), a significantly positive correlation between the escalations in D-dimer levels in older people and young patients. The mean D-dimer levels exceeding 500 ng/ml were shown to have approximately 1.12 ODD, particularly in the age group of 35 to 60. The age range of the infected sample included newborns to elderly individuals, with 33.3% of infected samples being under 35 and two-thirds being over 35. This suggests that those in the mid-aged and older group had a higher risk of contracting the infection. According to a 2022 study by Statsenko et al., older patients had a higher risk of being hospitalized in the critical care unit and were more vulnerable to severe COVID-19 instances than their younger counterparts [28]. Bruine de Bruin who concluded that older adults have higher risks for mortality due to coagulopathy conducts another study that emphasizes the same result [29]. The World Health Organization (WHO) states that age is a risk factor for COVID-19 infection and that older people are more susceptible to serious disease outcomes. Age was directly correlated with the risk of getting COVID-19 severity and death, according to several researches conducted during the epidemic [28, 30, 31] [27, 29–31].
The current research has also evaluated the relationship between mutation in the FGA/FGG Factor and elevated D-dimer in COVID-19 patients. The results revealed that no impact between higher levels of D-dimer in COVID-19 patients and mutation of the FGA/FGG Factor. Likewise, a study published by Abu-Farha et al., 2020 has aroused the potential effect of rs13109457-A (G_A) FGG/FGA Factor mutation on escalating D-dimer levels[32]. In a previous study conducted by Nicholas L., Smith, 2011 reported no proved evidence on the association of FGG locus mutation and the D-dimer levels in hospital admitted patients [33]. The non-significant effect of FGG mutation could be attributed to several reasoning among them the ethnicity, Lu-Chen Weng, 2014 reported a significant effect for the FGG mutation in African American population whereas there was no significant effect among the Asian, and Hispanic populations [34]. Inversely, several studies showed that individuals with a mutation on other factors such as Factor V Leiden (FVL) had higher levels of D-dimer compared to individuals without the mutation. Indeed, the mutation on FVL exaggerates the threat of thrombus formation through the activation of Factor Va and VIIIa by 10 folds [35].