An essential aspect of treating the COVID-19 pandemic is focusing on the mortality rate and its associated risk factors. This has been a priority for healthcare decision-making centers in countries since the onset of the pandemic. Hence, this study retrospectively examined the correlation between demographic data, intubation, laboratory parameters, and the death rate in patients with COVID-19.
The present investigation found a significant correlation between intubation and the mortality rate of patients with COVID-19. The mortality rate among patients on mechanical ventilation was 97.6%. Similar studies have found that the mortality rate for COVID-19 patients on mechanical ventilation ranges from 86–97% (14, 15). In line with the present study's findings, the research conducted by Chang R et al. (2021) showed a correlation between intubation and the mortality rate of COVID-19 patients admitted to the intensive care unit (16). The insufficient training and expertise of nurses in operating mechanical ventilation devices, improper configuration of the device following intubation, and untimely intubation might contribute significantly to the rise in death rates among patients receiving mechanical ventilation. The study conducted by Zirpe KG et al. (2021) revealed that the death rate among patients who underwent early intubation was 60%, whereas for those who underwent late intubation, it was 77.7% (17). These results have collectively raised concerns about the low survival rate among individuals who experience mechanical ventilation (18, 19).
The current investigation demonstrated a direct correlation between the severity of abnormalities observed in chest X-ray and CT scan results of the lungs and the mortality rate of COVID-19 patients. Imaging technologies are crucial in promptly diagnosing and treating COVID-19 patients (20). Consistent with the results of this study, previous research in this area has consistently shown a clear and substantial correlation between the extent of lung involvement, disease severity, and mortality rate. Specifically, the mortality rate was significantly higher among COVID-19 patients who had severe lung involvement (21–24). Hence, unusual lung CT scan results signify an unfavorable disease prognosis (25).
The current investigation found that the mortality rate in COVID-19 individuals was directly correlated with the presence of a prior history of underlying kidney illness. Shetabi et al. (2022) also found that 24 out of 28 COVID-19 patients with kidney diseases died (26), which is consistent with the current study's findings. Cai R et al. (2021) found that the mortality rate among patients with renal difficulties and COVID-19 was substantially greater than among patients with kidney problems without COVID-19 infection (27). Cheng Y et al. (2021) also showed that intensive care unit intubation and specialist treatment were necessary for patients with elevated Creatinine (Cr) (28). Thus, even in patients with minor COVID-19 symptoms, monitoring renal function and paying attention to changes in the results of these tests is essential.
Severe infections and other acute systemic disorders might cause alterations in test parameters. The current study's conclusions about the correlation between blood test results and COVID-19 patients' death rates demonstrated that hospitalized patients' death rates rose as WBC, K, P, Urea, Cr, AST, and LDH levels increased. The values of these tests in patients who died from COVID-19 were higher compared to individuals who were discharged after recovering from COVID-19. Consistent with the findings of the current investigation, Nikseresht et al. (2020) observed a positive correlation between WBC, ALT, AST, LDH, and Cr levels, and the decrease in lymphocyte count, concerning the mortality rate (29). Pourbagheri et al. (2020) observed that individuals with COVID-19 commonly exhibited elevated ALT, AST, and bilirubin levels in laboratory tests and decreased albumin levels. An examination of 149 COVID-19 patients revealed that 28.8% exhibited elevated Cr levels, suggesting that COVID-19 could cause kidney damage (30).
The renal damage observed in patients with COVID-19 may be attributed to the direct cytopathic effects of the coronavirus on the kidney tissue (31). Furthermore, the coronavirus utilizes the angiotensin-converting enzyme 2 (ACE2) as a receptor for cellular entry, and the level of expression of the angiotensin 2 (ACE2) enzyme is higher in the kidneys (32). Early detection of polymerase chain reaction fragments of the coronavirus in the blood and urine of COVID-19 patients can avoid kidney damage and reduce mortality. Hence, the assessment of blood variables holds significance in the supervision and therapy of individuals with COVID-19, as alterations in these indicators could be linked to organ impairment, disease intensity, and fatality.
In contrast to the findings of the current investigation, Cao WJM (2020) demonstrated that Urea and Cr levels may not have a role in predicting the outcome of COVID-19 disease. Instead, they found that patients with severe symptoms of COVID-19 had elevated levels of ALT, AST, and lymphocytes (33). Contrary to the findings of the current investigation, Ferrari et al. (2020) found a decreased WBC count in COVID-19 patients (34). The discrepancy in the results may be attributed to the timing of monitoring inflammatory indicators, as WBC count may have stayed within a low or normal range during the initial phases of the illness.
Findings showed a statistically significant inverse correlation between COVID-19 patient mortality and PH, HCO3, and SaO2 levels. Consistent with our results, previous research has shown that a drop in SaO2 while hospitalized is an essential indicator of death in COVID-19 patients (35–38). As a result of hypoxia, vascular permeability increases, inflammatory cells accumulate, and lung damage progresses (39). To avoid the negative consequences of chronic hypoxia, which can lead to a lower rate of intubation and death in COVID-19 patients, it is crucial to detect hypoxemia early and provide oxygen to these patients as soon as possible during their admission and hospital stay.
This study identified a significant association between demographic characteristics and the mortality rate of patients with COVID-19. Specifically, it was revealed that advancing age significantly affected the mortality rate. Consistent with the results of this investigation, previous studies conducted during the COVID-19 pandemic have similarly documented the highest fatality rate among COVID-19 patients aged 60 and above (40, 41).
Limitations
One disadvantage of this study was that it was conducted exclusively at a medical education center in Tabriz, Iran, which served as an inpatient facility for COVID-19 patients. To ensure the results apply to a broader population, it is recommended that this research be replicated in additional medical facilities. There is a possibility that certain laboratory factors were not assessed in COVID-19 patients upon their hospitalization. Therefore, it is recommended that further studies be conducted on recently diagnosed patients to obtain more comprehensive findings.