The present study was conducted to examine the nutritional status of COVID-19 patients and its relationship with clinical outcomes of the disease, including disease complications, severity, and length of hospitalization. The MNA and GLIM tools were used to determine the nutritional status of patients, and their concordance was examined.
The data analysis in this study shows a significant relationship between the reduction of systolic (SBP) and diastolic blood pressure (DBP) with the nutritional status of COVID-19 patients (p-value = 0.04, 0.01 MNA: SBP, DBP, and GLIM: SBP, DBP p-value = 0.038, 0.008), where systolic blood pressure decreased by 6–8 units and diastolic blood pressure decreased by approximately five units. There are various mechanisms for this phenomenon; on t one hand, it can be said that systemic oxidative stress plays a fundamental role in causing high blood pressure, which is prevented by calorie intake limitation, and as a result of the endothelium-dependent vasomotor function, blood pressure decreases24. The study conducted by Kunduraci et al. on patients with metabolic syndrome showed that calorie intake limitation could reduce blood pressure25. Additionally, Alam et al. examined the effect of limited calorie intake on cardiovascular factors such as blood pressure and found that calorie intake reduction can lead to a decrease in systolic and diastolic blood pressure26.
The oxygen saturation level (SaO2) of patients is another factor that was observed to have a significant difference between normal and malnourished states in this study through the performed analyses (MNA: p-value = 0.01 and GLIM: p-value = 0.012). According to the obtained results, consuming non-normal food causes a decrease of approximately 2.5% in the oxygen saturation level in malnourished individuals compared to normal individuals. Insufficient intake of iron-containing foods can lead to a decrease in the available iron for hemoglobin production, which can limit the blood oxygen saturation level27. Another factor involved in hemoglobin biosynthesis is the active form of vitamin B6 (pyridoxal 5-phosphate or PLP), and also the amino acid glycine. PLP is the co-factor of the amino levulinic acid synthase (ALA) enzyme, which is the first enzyme in hemoglobin biosynthesis and its role is to combine glycine and succinyl-Coenzyme A (succinyl-CoA) as the initial step in hemoglobin production 28. Therefore, it can be concluded that one of the consequences of malnutrition is insufficient intake of vitamin B6 and glycine, which can disrupt the process of hemoglobin production and lead to a decrease in oxygen saturation level and hypoxia.
Based on this information and its analysis, it can be said that nutritional status can be considered important for managing the clinical consequences of COVID-19 and reducing its complications. Various studies have been conducted to determine this importance; for example, Bedock and colleagues examined the nutritional status and its relationship with the severity of the disease in 114 patients with COVID-19 in their study. The importance of initial nutritional screening in patients with COVID-19 was emphasized in this study22. Additionally, Rouget and colleagues calculated a high rate of malnutrition (37.5%) in patients with COVID-19 in their study, and based on this data, it was determined that nutritional support is essential in COVID-19 care29. Mohammadi and colleagues found that nutritional status is of particular importance in hospitalized patients with COVID-19, and malnutrition can lead to longer hospitalization periods and even increased mortality in these patients30.
In this study, the GLIM criteria were compared with the MNA tool to determine their validity and reliability in assessing nutritional status. The analyses showed that the MNA tool and GLIM index had a relative agreement based on Cohen's analysis with a value of 0.35 and a p-value < 0.0001. Furthermore, the GLIM criteria were found to be more practical and accessible, making it a suitable tool for assessing the nutritional status of individuals, especially those suffering from malnutrition. As Shahbazi et al. also demonstrated, the GLIM criteria provide a fast diagnostic power with adequate accuracy and reliability and can be a good diagnostic tool for assessing nutritional status due to the reduced time for patient interaction21. However, other studies have found that the GLIM criteria are not a precise and reliable measure for assessing the severity and prevalence of malnutrition, contrary to our study's findings. For example, Rouget's study used the GLIM criteria to determine the level of malnutrition in patients with COVID-19 and ultimately reported that GLIM may not accurately determine the prevalence of malnutrition29.
In this study, we analyzed each item of MNA and GLIM separately in hospitalized and non-hospitalized ICU patients. The results showed significant differences between hospitalized and non-hospitalized ICU patients in item 1 of MNA (p-value = 0.01), which is related to a reduction in food consumption in the three months before the disease, and item 3 (p-value = 0.003), which is related to the level of patient mobility during hospitalization. Approximately 67.8% of non-hospitalized ICU patients had a moderate reduction in food intake in item 1 of MNA, while 41.6% of hospitalized ICU patients had a moderate decrease in food intake in the three months before COVID-19. On the other hand, 18.8% of non-hospitalized ICU patients did not have a decrease in food intake, and 58.3% of hospitalized ICU patients did not have a decrease in food intake. It can be interpreted that hospitalized ICU patients consume more medication, including corticosteroids. One of the side effects of these medications is an increase in patients' appetite31, as some hospitalized ICU patients reported an increase in their appetite and food intake during hospitalization.
In the analysis conducted on item 3 of the MNA tool, which relates to patients' mobility, approximately 5.6% of non-ICU hospitalized patients and 33.3% of ICU hospitalized patients were unable to get out of bed; 49.6% of non-ICU hospitalized patients and 50% of ICU hospitalized patients could get out of bed but were unable to walk, and 44.7% of non-ICU hospitalized patients could leave the ward and walk, while only 16.7% of ICU hospitalized patients had this ability. The reason for this is related to the clinical condition of patients and their hospital ward, where COVID-19 patients hospitalized in the ICU due to various reasons, including low oxygen saturation and shortness of breath, have less mobility compared to non-ICU hospitalized patients.
In this study, there were also some limitations. In addition to the MNA tool and GLIM criteria, we also used the NUTRIC-score questionnaire, but meaningful data could not be obtained due to the low number of analyzed patients. Furthermore, due to limitations in facing patients to measure their nutritional status using the GLIM criteria, their muscle mass was not determined from the phenotypic criteria, which based on previous studies, does not affect the results17. Additionally, since all patients were diagnosed with COVID-19, inflammatory conditions were considered for all of them.