The Coronavirus disease 2019 (COVID-19) is currently a worldwide pandemic. The morbidity and mortality rates are still increasing, especially in developing countries such as Indonesia. More than one million Indonesians suffer from COVID-19. Data from several studies indicate high morbidity and mortality rates in the elderly population. The incidence rate of COVID-19 in the population is around 11-17%, while the case fatality rate (CFR) is around 8.9% and increases with age. ^{1 – 5}

The elderly population has an immunosenescence state, a condition that causes disturbances in both innate and adaptive immune systems. COVID-19 in the elderly results in a continuous inflammatory response, causing the clinical symptoms of COVID-19 in the elderly to often be more severe and the mortality rate to be high. ⁶

Survivors of COVID-19 have an increased risk of psychiatric disorders. About 20% of COVID-19 survivors will experience mental disorders. The most common clinical manifestations are depression, anxiety, and sleep disturbances. ^{6 – 10}

Mental disorders increase along with the increasing age of COVID-19 survivors. The pathogenesis of psychiatric disorders in COVID-19 survivors is a continuous inflammatory state that can result in disturbances in neuroendocrine, neuroimmune, and nervous structures. ^{11 – 15}

A total of 52.7% of the elderly population who were infected by COVID-19 suffers from malnutrition. This is due to the fact that most elderly people who suffered from COVID-19 have multiple comorbidities. In addition, the inflammatory reaction causes high catabolism, causing high protein consumption for the formation of acute phase reactants. The expression of angiotensin-2 receptor (ACE-2) in the gastrointestinal tract is high which causes symptoms of nausea, vomiting, diarrhea, and reduced appetite to increase in the elderly. The ongoing inflammatory reaction that occurs in the elderly results in a higher risk of malnutrition even when they have survived COVID-19. ^{16 – 20}

The risk of mental disorders and malnutrition in elderly COVID-19 survivors can lead to fragility. The fragility of elderly COVID-19 survivors increases hospitalization rates and mortality ( Figure 1). ^{17 , 21 – 25}

The aim of this study was to investigate the risk of mental disorders and malnutrition in elderly COVID-19 survivors.

This study invited 158 participants; 56 participants refused and did not respond the questionnaire. Two had missing data on the dependent variable and could not be contacted for confirmation of research data. A total of 100 participants were studied ( Figure 2).

A total of 100 respondents were tested based on baseline characteristics; p-values were over 0.05, so it can be concluded that there was no significant differences in the characteristics of respondents. The variable of availability of caregivers or nurses while being infected with COVID-19 for those who have a disorder did not show any significant differences; this is because the number of respondents who were outpatients is small.

As seen in Table 1, there was no difference in the occurrence of mental disorders between sexes; men and women had almost the same percentages. There was no difference in the occurrence of mental disorders between the different professions, nor was there a difference in the occurrence of mental disorders between those with caregivers and those without. Regarding treatment, a difference was observed because most of the elderly population infected with COVID-19 are likely to receive treatment in hospitals.

The characteristics of the malnourished group also showed there was no difference in baseline characteristics (gender, profession, caregiver, income, vaccinated status), where the characteristics of the respondents in patients who had malnutrition and those who did not suffer from malnutrition were homogeneous.

In Table 2 there are no differences between gender, profession, and availability of caregivers’ effect on the risk of malnutrition. However, there was a difference between treatment during COVID-19 infection and the risk of malnutrition; this may be because most elderly people infected with COVID-19 get treatment in hospitals.

Based on the results in Tables 3 and 4, the variables of age, symptoms, and comorbidities were included in the multivariate analysis, both for mental disorders and malnutrition disorders.

Table 3 shows there was a relationship between increased age and the risk of mental disorders. There was also a relationship between the severity of COVID-19 symptoms and the number of comorbidities with the risk of mental disorders.

Table 4 shows a relationship between increasing age and the risk of malnutrition. There was also a relationship between the severity of COVID-19 symptoms and the number of comorbidities with the risk of.

Based on the results of the multiple logistic regression analysis in Table 5, the factors that influenced mental disorders were age and symptoms. People older than 70 years had a three-time greater risk of experiencing mental disorders than the elderly aged between 60-70 years old, after controlling for symptoms and comorbidities variables at a 95% confidence interval (CI) between 1,071 to 8,83. The elderly with severe COVID-19 symptoms were at a 4.5-time greater risk of experiencing mental disorders compared to the elderly with mild symptoms, after controlling for age and comorbidities variables at a 95% confidence level between 1.23 to 16.71.

Based on the results of multivariate analysis, malnutrition disorders were influenced by symptom variables and comorbidities. Elderly people with more than one comorbidity had a 6.6-time greater risk of experiencing malnutrition after controlling for symptoms and age variables at a 95% confidence level, between 1.56 to 28.57.

One-third of the post-COVID-19 population experience mental disorders; 40% of patients will experience depression, and the rest will experience symptoms such as anxiety, and delirium. ^{10 , 11 , 23 , 31 - 33} Between 43-70% of COVID-19 survivors experience psychological disorders. Several studies say this is related to the degree of disease, age, and comorbidities. However, several studies have stated that mental disorders are not related to this, especially in the elderly. ^{5 , 6 , 14 , 15}

The older the age, the higher the risk for mental disorders will be. Based on the results of our study, it was found that as age increased, the risk of mental disorders in the elderly after COVID-19 infection increased by 2.5 times according to the results of the study in Tables 3 and 5. ¹⁶

COVID-19 infection predisposes to mental disorders, which are induced by cytokine bodies and hyperinflammatory states. ^{10 , 11} Therefore, it can cause disruption of the blood-brain barrier and ultimately inflammation of the nervous system. In the elderly, there is a susceptibility to inflammation. ¹⁷ Hyper-inflammatory conditions affect the severity of COVID-19 disease; the severity of COVID-19 disease will increase the risk of post-infection mental disorders. In addition, comorbidity in the elderly is often multi-comorbid. ¹⁷ The number of comorbidities increases the risk of mental disorders. ^{23 , 32 , 34} Table 3 shows that there is a relationship between age, the degree of disease severity, and comorbidities that increase the risk of mental disorders in the elderly after COVID-19 infection. The degree of severe illness leads to a 4.5 times higher risk of mental disorders and multi comorbidities lead to a 2.3 times higher risk of experiencing mental disorders. ³⁴

Malnutrition is a nutritional disorder that has an unfavorable impact, especially on the elderly. The incidence of malnutrition in the elderly infected with COVID-19 is higher than in the general population. The pathomechanism of malnutrition is an acute inflammatory state causing high body protein consumption, and less lean body mass in the elderly, which continues to decrease with increasing age so that elderly people often lose weight due to acute inflammation. The infection of SARS-CoV-2 in the gastrointestinal system of the elderly is greater, so elderly people who are infected with COVID-19 often experience severe gastrointestinal disorders. Other factors can also influence malnutrition: the severity of COVID-19 infection increases the risk of malnutrition as 32.3% of the elderly infected with COVID-19 will continue to be malnourished 30 days after infection. Comorbidity in the elderly is also related to the incidence of malnutrition, which is related to chronic inflammation that leads to acute exacerbations causing a hyperinflammatory state so that catabolism increases and muscle mass is used. ^{10 , 12 , 18 , 19 , 35 , 36}

Based on the results of the study, it was found that older age, degree of disease severity, and comorbidities were associated with the risk of malnutrition in the elderly after COVID-19. Increasing age increased the risk of malnutrition by 2.5 times. The severity of the disease also increased the risk of malnutrition, although in this study it was shown that people with the moderate disease had the highest risk of malnutrition, which was 6.3 times higher, while people with severe degree disease had 4.4 times risk of malnutrition. In some studies, 32.3% of patients suffering from malnutrition during treatment still experienced malnutrition on day 30, meaning about 70% experienced an improvement in their condition. In this study, multi-comorbidities led to 6.6 times higher risk of malnutrition, more comorbidities, and increased susceptibility in the elderly as seen in Table 6. Table 6.

Variable	P-Value	OR	95% Confidence interval
			Lower	Upper
Age
60-70 yo*
>70 yo	0.114	2.515	0.800	7.906
Symptoms
Mild*	0.003
Moderate	0.001	6.368	2.047	19.812
Severe	0.029	4.420	1.163	16.802
Comorbidities
None*	0.007
1 Comorbidity	0.005	5.045	1.645	15.472
>1 Comorbidity	0.010	6.685	1.56	28.57

Key: * reference group.

Age, COVID-19 symptoms and the presence of disease comorbidities are risk factors for mental disorders and malnutrition in COVID-19 elderly survivors. The older the age, the more severe the symptoms of COVID-19; the number of comorbidities also increased the risk of mental disorders and malnutrition.

Evaluation of mental health and nutritional status in elderly COVID-19 survivors needs to be carried out regularly to avoid vulnerabilities which will negatively impact the quality of life of elderly people.

The limitations of this study are the total sampling approach. In addition, in this study some variable confounders couldn’t be strictly controlled. Variable confounders that can affect the results include mental disorders that have previously been experienced or have had previous symptoms.