Discussion
In the last one year, the prevalence of COVID-19 infection has increased on a daily basis among all over the world. As a result, determining the severity and mortality of the disease is necessary in order to minimize the pandemic’s spread. Many studies have identified clinical features of COVID-19 patients, including epidemiological, clinical, laboratory, radiological, and treatment results. Laboratory findings at the time of admission to hospital were shown as important differences between severe and non-severe patients. In addition, the role of several laboratory parameters in the evaluation of the disease severity of COVID-19 in hospitalization has been revealed in some previous studies. (3, 7-9). In this study, our aim was to evaluate whether hematological parameters and ferritin level predicted the mortality of patients and whether they had an effect on the duration of hospitalization in patients treated by hospitalization.
It has been stated that as the age of infected patients rises, so does the mortality rate, with the crude mortality rate in people over 80 years old being 21.9 percent (4). Multivariate analysis showed that old age and high concentration of LDH were independent predictors of poor prognosis in a retrospective study (10). As a consequence, identifying and diagnosing serious or critical patients is vital. This study showed that the patients’ median age was 70 years, with a range of 19 to 98 years. In a study comparing moderate and severe patient groups, no significant difference was found in terms of gender (4). It was observed that the number of female patients hospitalized was higher than the number of male patients in this study. However, the majority of patients who did not respond to treatment and had mortality were males. In patients who responded to the treatment and could be discharged, the duration of hospitalization was observed to be longer in women.
According to a meta-analysis report, COVID-19 severity is associated with higher WBC counts and lower lymphocyte, CD4+ T cell, and CD8+ T cell counts in COVID-19 patients. (11). The decrease in lymphocyte count appears to be directly proportional to the severity of COVID-19 infection. Wang et al. reported that leukocyte, neutrophil, NLR, platelet-to-lymphocyte ratio in the severe group were significantly higher than those in the moderate group; additionally the study reported that lymphocyte, eosinophile, and hemoglobin in the severe group were significantly lower than those in the moderate group (4). In our study, leukocyte, neutrophil and NLR levels were found to be statistically significantly higher in patients with mortality. At the same time, hemoglobin, lymphocyte, eosinophil and albumin levels were found to be statistically significantly lower in patients with mortality. This may be due to long-term infection and hypoxia, which allows the bone marrow to compensate by producing more granulocytes. SARS-CoV-2 can continue to invade more lymphocytes, proliferate, and cause lymphocytes to die or become exhausted when they enter the spleen and other immune organs, resulting in severe lymphopenia in patients with mortality (4). Fan et al. reported that mild thrombocytopenia and leukopenia were found in some COVID-19 positive patients at first admission. Additionally, they showed that on admission; older age, lymphopenia and raised LDH were associated with intensive care unit admissions (12). In previous years Xu et al. reported that thrombocyte counts are substantially low in pneumonia patients, and this drop is directly proportional to the patients’ clinical status(13).
Henry et al. reported that both serious and fatal COVID-19 patients had elevated biomarkers of cardiac and muscle damage. Patients who deceased due to disease had substantially elevated cardiac troponin levels at the time of diagnosis. When these results are coupled with substantial elevations in liver enzymes (alanine aminotransferase and aspartate aminotransferase), renal biomarkers (blood urea nitrogen, creatinine), and coagulation steps, an image of multiorgan failure appears in patients who experience the extreme type of the disease. In one study, increased serum ferritin levels were reported among patients who did not survive compared with patients who survived(14). This important result was also observed in another meta-analysis study among severe and non-survival patients with COVID-19 infection(15). Similarly, in our study, ferritin values were found to be significantly higher in patients with mortality on admission to the hospital. Among other biochemical parameters evaluated during hospital admission, ALT, urea, uric acid, CK, D-dimer and LDH were found to be statistically significantly higher in patients with mortality. On the other hand, it was observed that the albumin value at admission in these patients was statistically significantly lower than the patients who were discharged.
Our study had some limitations. First, this study was retrospective. Second all patients included in the study consisted of patients who were hospitalized due to their symptoms. Outpatients with mild symptoms were not included in the study and blood values were not known at the time of diagnosis. However, in this study, it has seen that it is important to associate the onset of symptoms (days of illness) with hematological parameters. In conclusion, multiple laboratory parameters can be related to the severity and mortality of COVID-19 infection and should be screened and assessed on a regular basis as the pandemic progresses. WBC count, neutrophil, lymphocytes, NLR, eosinophil, platelet count, ferritin, ALT, urea, uric acid, CK, albumin, D-dimer, and LDH were among the parameters tested. This study indicates that by using the most simple and routine hematological tests at the time of COVID-19 diagnosis, it may be possible to predict a patient’s prognosis. This will help patients receive early clinical care, reducing patient mortality and aiding in the control and prevention of the outbreak.