INTRODUCTION
At the beginning of the coronavirus disease (COVID-19) outbreak, approximately 15% of the first deaths were people over the age of 60, encouraging strict social isolation to prevent infection; this negatively affected mental health with increased fear, anxiety, and isolation [1,2]. Reduced social interaction has led to increased frustration, anxiety, depression, stress, and fear of COVID-19 infection [2–5]. Psychological problems such as fear of COVID-19 and loneliness have been found to affect the quality of life of older people [2].
COVID-19 has also had a great impact on the physical activity of older people [4,6,7]. Due to quarantine and closure by COVID-19, the level of physical activity decreased significantly, resulting in physical fitness degradation, weakness, and the frailty of older people [7,8]. Changes in intake due to decreased physical activity were factors that aggravated sarcopenia, such as decreased muscle mass and increased body fat [4]. In a study comparing physical activity in 2020, the time of COVID-19, and the previous year, the frequency of going out of seniors aged 60 or older decreased by 54.2% for men and 62.6% for women. Physical activity also decreased by 43.6% in men and 52.8% in women [7]. In particular, the sedentary behavior also increased, indicating that it was a factor causing sarcopenia.
Sarcopenia is defined as a condition in which muscle function is reduced due to a decrease in the amount of muscle mass [9]. The focus of the diagnosis of sarcopenia in older people is to check the decrease in the quantity and quality of the muscle due to the decrease in muscle strength [10]. If there was no activity for 2 weeks, muscle atrophy of the lower extremities was about 2%, the lean mass of the lower extremities was changed. At the same time, the strength of knee extension was decreased by 7% [11]. World Health Organization added sarcopenia to the 11th edition of the International Classification of Diseases in 2017 [12], In Korea, the diagnosis code for sarcopenia was added in the 8th revision of the 2020 Korean standard cause of disease classification and recognized as a disease [13]. The Asian Working Group for Sarcopenia (AWGS) defined definition of sarcopenia as a state in which physical performance decreases due to age-related muscle loss and muscle weakness [9]. In 2019, they established a diagnostic algorithm, setting muscle strength thresholds of less than 28 kg for men and less than 18kg for women based on grip strength, and established cutoff criteria for low physical performance and short physical performance battery [14].
Sarcopenia is prevalent in older people and is a major risk factor for pneumonia by causing reduced immunity and lung capacity [15]. Sarcopenia in older people is also associated with falls, fractures [12,15], mortality [15], and quality of life [16]. It is very important to check sarcopenia in older people at an appropriate time and manage it so that it does not worsen [16–20]. Research trends show that sarcopenia is greatly affected by psychological factors such as loneliness, isolation, anxiety, fear, and depression [1,12,21].
After the COVID-19 pandemic, research on sarcopenia was expanded into the correlation between the physical activity of older people and the social distancing policy. Isolation and lockdown due to COVID-19 significantly reduced the level of physical activity, resulting in decreased physical strength and weakness in older people, and increased sedentary behavior was found to be a factor in sarcopenia [4,22]. Those with depressive symptoms and low social support were found to have low muscle mass, strength, and function [21]. However, there were few studies that simultaneously considered psychological and physical activity factors of sarcopenia during the COVID-19 pandemic. Therefore, to prepare basic data for establishing strategies to prevent and manage sarcopenia in older people during the COVID-19 period, research is needed to identify various risk factors for sarcopenia, including both physical and psychological variables in older people.
The specific purposes of this study are as follows: 1) To determine the prevalence of sarcopenia in older people in the community. 2) To identify risk factors for sarcopenia in older people in the community.
METHODS
1. Research Design
This study is a descriptive research design to confirm the prevalence of sarcopenia in older people living in the community and to identify related factors.
2. Participants
This study was conducted with older individuals (65 years or older) among older people registered at the Center for Older People Living Alone and the Senior Industrial Innovation Center located in S city, Korea. The criteria for selection of participants were those who could communicate, had been informed of the purpose and method of the study. Older people over 90 years of age were excluded from this study to prevent the risk of safety accidents during the physical performance measuring at home due to poor physical mobility. The target sample size was calculated based on the logistic regression sample size calculation formula proposed by Hsieh [23]. According to prior research [24], the prevalence of sarcopenia was 45%, and the odds ratio for the risk factor by gender was 2.1. Therefore, with OR=2.1, p=.45, ⍺=.05, and β=.05, a total of 98 individuals were calculated. Accounting for potential dropout rates, data collection was conducted with a sample of 110 individuals. After excluding seven incomplete response data copies, 103 data points were used for the final analysis. This study received ethical approval from Eulji University Institutional Review Board (NO: EU21-056).
3. Measurements
1) Sarcopenia
Sarcopenia can be evaluated by three criteria: strength, muscle mass, and physical performance presented by EWGSOP (European Working Group on Sarcopenia in Older People) and AWGS [9]. The prevalence of sarcopenia was calculated as the percentage of people with a SARC-F (Simple Questionnaire to Rapidly Diagnose sarcopenia) score of 4 or more and a grip strength of less than 28 kg for men and less than 18 kg for women. In this study, by applying the 2019 revised AWGS diagnostic criteria, the sarcopenia questionnaire tool SARC-F, muscle strength evaluation, and physical performance are evaluated in three ways. ① SARC-F: The simple sarcopenia self-diagnosis tool developed by Malmstrom and Morley [25] was adapted for Koreans by Kim et al.[26]. The total score ranges from 0 to 10, with a high score indicating more severe muscle loss, and a score of 4 or higher indicating suspected sarcopenia. The reliability of the tool was Cronbach's ⍺=.78 [25] and .87 in this study. ② Muscle strength: Muscle strength was measured using a digital dynamometer (PGF-1000, China) to assess grip strength. After stretching the arms in a standing position, each hand was measured twice, the highest value was recorded, and the average value was used [12]. A higher score indicates a stronger grip strength. The standard for lowering grip strength is less than 26 kg for men and 18 kg for women based on the AWGS [9]. ③ Physical performance: To measure physical performance, the Short Physical Performance Battery (SPPB) developed by the National Institute of Aging (NIA) [27]. It consists of three items: standing balance, gait speed, and repeated chair stands. If the total score was less than 9, it was judged that there was a problem with physical performance [28].
2) Fear of COVID-19
The tool developed by Ahorsu et al. [29] was translated into Korean by Hwang et al. [30]. The tool consists of seven items with three physiological responses to COVID-19 and four emotional responses. The higher the score, the higher the level of fear of COVID-19. The reliability of the tool was Cronbach's ⍺=.82 at the time of development and .82 in this study.
3) Distress
Among the Distress Thermometer & Problem List (DT & PL) tool, developed by the National Comprehensive Cancer Network in the United States, DT was employed to assess the level of emotional stress [31]. DT is an 11-point visual event scale ranging from 0 to 10, with the degree of emotional stress experienced over the past week being scored on a DT. A higher score indicates higher distress, a score of 4 or less reflects mild distress, and a score of 4 or more reflects severe distress.
4) Depression
Depression was measured using the Geriatric Depression Scale (GDS) Short Form [32]. We used the GDS Short Form Korean Version (GDSSFK)[33]. A score of 0~4 indicates normal, a score of 5-8 indicates mild, a score of 9~11 indicates moderate, and a score of 12~15 indicates severe depression. At the time of development, the reliability was .88, and .86 in this study.
4. Data Collection
The data collection period for this study was from August 24 to December 28, 2021. After obtaining permission from the senior centers, data were collected from older people who received home visits or participated in the center's health events. While social distancing was implemented due to COVID-19, research assistants collected data by directly visiting the participants’ homes in compliance with the home visit restrictions and permitted periods instructed by S City and the Center for older people Living Alone. Data were collected from those registered at the senior center who visited the center in November during the With Corona period. Data collection was conducted by research assistants, who were nursing students who received 3 hours of prior education and training on home visit quarantine, communication with older people, surveys, and measurement of SPPB. For older people who were unable to complete the survey on their own, the assistants read the survey questions directly and conducted the survey. The time taken to collect the data was 20 to 30 minutes.
5. Data Analysis
The collected data were analyzed using the statistical program SPSS 26.0 (IBM Corp., Armonk, NY, USA). Participants’ demographic characteristics were analyzed using frequency, percentage, mean, and standard deviation. Factors related to the risk of sarcopenia according to health factors were analyzed using univariate ordinal logistic regression analysis. As for the factors affecting sarcopenia, the factors related to sarcopenia were confirmed by multivariate ordinal logistic regression using variables that were significant in the univariate analysis as independent variables.
RESULTS
1. General Characteristics of the Study Participants and Scores of Research Variables
The demographic characteristics of the study participants were 65~74 years (43.7%), and the average age was 75.88 years. The 97.1% of the participants were vaccinated against COVID-19, but their experience of self-quarantine was very small (3.9%), and most of them were older people with no history of infection. This is because the research subjects included vulnerable groups who spent most of their time at home even before the COVID-19 pandemic. The average SARC-F score was 3.02±3.08 and grip strength was 25.71±7.53 kg for men and 15.41±5.96 kg for women. SPPB was 10.31±1.90 points for older men and 8.88±3.02 points for older women, and older women scored less than the cutoff score of 9 points. The fear of COVID-19 showed an average of 16.21±5.82 points. The average scores for distress and depression are 3.63±2.89 and 4.25±3.87, respectively (Table 1).
Table 1.
General Characteristics of Study Participants and Scores for Research Variables (N=103)
2. Prevalence of Sarcopenia
Table 2 shows the prevalence of sarcopenia among the participants. In the group with a SARC-F score of 4 or higher, 8 older men (7.8%) and 33 older women (32.0%) were included. Among them, 5 men (4.8%) and 30 women (29.1%) weighed less than 28 kg and 18 kg respectively, according to the grip strength criteria.
3. Risk Factors of Sarcopenia
Prior to identifying the risk factors affecting sarcopenia, age, gender, education level, subject economic status, residence type, physical performance ability, and depression were found to be significant in the univariate analysis (Table 3). Table 4 shows the results of the multiple logistic regression analysis by inputting the significant variables as the independent variables. In the Hosmer-Lemeshow test, which is a test of suitability for logistic regression, the p-value was .408, indicating that the null hypothesis was adopted and that the regression model was suitable. The explanatory power of the regression model for the dependent variable was 70.1% and the classification accuracy was 88.3%. Age (OR=14.48, CI=1.48~141.40), gender (OR=6.69, CI=1.11~40.06), physical performance (OR=7.41, CI=1.55~35.21) and depression (OR=5.29, CI=1.16~24.06) were significant risk factors for sarcopenia, but COVID-19-related factors were not significant (p>.05) (Table 4).
Table 3.
Risk Factors for Sarcopenia Estimated by Univariate Ordinal Logistic Regression Analysis (N=103)
Table 4.
Risk Factors for Sarcopenia Estimated by Multivariate Ordinal Logistic Regression Analysis
DISCUSSION
Based on the results of this study, the prevalence of sarcopenia was 7.8% in older men and 32.0% in older women based on the SARC-F diagnostic criteria. Compared to the 4.2% in men and 15.3% in women given in a cohort study of 1,222 older Korean people aged 70 years and older in 2016, before the COVID-19 period, this study showed a higher prevalence of sarcopenia. The difference in prevalence according to gender was approximately four times higher in women than in men [26], which was similar to the results of this study. According to the AWGS diagnostic criteria revised in 2018, among those with a SARC-F score of 4 or higher, if a person with a grip strength of less than 28 kg for men and less than 18 kg for women is diagnosed with sarcopenia [9], the prevalence of sarcopenia that satisfies both conditions at the same time was 4.8% for older males and 29.1% for older females, and the risk of sarcopenia was about six times higher in older females than in the older males. This was a higher result compared to 1.7% for men and 4.6% for women when the prevalence of sarcopenia was diagnosed with SARC-F and grip strength in 2,123 older people 70 years of age or older in Korea in 2016[14]. However, this result is lower than the prevalence of sarcopenia, which was measured by walking speed and muscle strength in older people residing in Japanese nursing homes, at 38.0% for men and 62.0% for women [18]. The reason for this difference was that the average age of this study was 75.8 years, in Kamo's study [18], which targeted older adults with an average age of 86.4 years old, the proportion of older women was also high at 82.4 %, showing a high prevalence of sarcopenia. In addition, the study by Kim & Won [14] is considered that the prevalence of sarcopenia was low because only older individuals who were able to walk were investigated.
As a result of performing a logistic regression analysis to identify related factors of sarcopenia, gender, age, physical performance, and depression were ultimately confirmed as significant factors, but COVID-related variables such as fear of COVID-19, experience of COVID-19 testing and self-quarantine, and vaccination status were not significant factors. The most relevant factor is age, according to the results of this study, the oldest adults (85 years or older) had a 14.48 times higher risk of sarcopenia than the younger people (65 years or older, less than 75 years old). The risk of sarcopenia was high in people over 85 years of age. Sarcopenia occurs during aging and occurs with ad-vancing age [12]. A study on 85-year-olds [22], and a study on older people living alone living in the Chinese community [6], a study on older patients with knee osteoarthritis [17], a study on older people aged 70 or older living in a senior residence [21], the prevalence of sarcopenia increased with age, supporting the results of this study. In terms of gender, the risk of sarcopenia was higher among older women than among men [21]. Based on this study, older women had a 4.58 times higher risk of sarcopenia than older men. A study investigating risk factors for sarcopenia among older people in Hong Kong during COVID-19 also supported this study by reporting that women have a 1.5 times higher risk of sarcopenia than men [22]. In particular, because of analyzing factors affecting muscle strength according to gender, older women had lower muscle strength than older men, and looking at the difference in factors affecting muscle strength, older women were more stressed, perceived themselves as more obese, and had the lower quality of life than men [21]. In studies on older people in Korea and Japan, older women were consistently identified as a risk factor for sarcopenia, supporting this study [14,18,26].
Physical performance was also identified as a risk factor for sarcopenia. In this study, the physical performance- restricted group with a cutoff score of 9 or less in the SPPB score measured for muscle function was 7.41 times more likely to have sarcopenia than the normal group. Sarcopenia has been known to predict a poor prognosis, such as falls and death, when muscle function is reduced, such as a decrease in walking speed [12]. Among the independent variables input to the regression model of the Barthel ADL index, which evaluates the level of daily activities for older people in nursing homes in Japan, SPPB, grip strength, and age were significantly higher [18]. In order to prevent and maintain daily life, it is necessary to prepare an intervention plan to detect and prevent the degree of sarcopenia in advance. In addition, a study on older Chinese people reported that obesity level and physical activity were factors affecting sarcopenia, supporting the results of this study [6].
During the COVID-19 pandemic, Brazilian adults' moderate to vigorous physical activity decreased by 59.7% due to self-isolation, and sedentary behavior increased by 42.0% [35]. Because older adults aged 55~65 spent more time sedentary than younger adults and middle-aged adults, the decline in physical activity was greater in the older group even during the COVID-19 pandemic, similar to the results of this study. Previous studies have shown that the decrease in the level of physical activity, such as a long time at home due to social policies such as social distancing due to low social interaction and social distancing due to COVID-19, is greatly affected by older people living alone [4]. The fact that this study was conducted during a period when strict social distancing policies due to COVID-19 were implemented and that approximately 61% of the study subjects were older people living alone is thought to be related to the high prevalence of sarcopenia.
Depression was also identified as a risk factor for Sarcopenia. In this study, the risk of sarcopenia was 5.29 times higher in the group with depression than in the group without depression. With prolonged COVID-19, the incidence of depression among older people also increased, and even among older people without a history of depression, the risk of developing depression increased by 2.4 times compared to before COVID-19 [5], and the mental health of older people was also very vulnerable. During the COVID-19 period, the risk of infection and isolation in quarantine facilities increased negative emotions such as stress, fear, and anger [34], and vulnerability to depression and mental health in older people increased compared to before COVID-19 [5] People with mental disorders have decreased moderate to vigorous physical activity and spend more time sitting, resulting in decreased activity performance [35].
Although sarcopenia in older people during the COVID-19 pandemic has not been proven to have statistical significance with COVID-19-related variables, depression, and reduced activity in older people, which were further amplified during the COVID-19 period, have been proven to be more influential factors in the worsening of sarcopenia in the older. In a study of factors affecting sarcopenia in older people with knee arthritis, the lower the depression score, the lower the sarcopenia by 0.5 times [17], supporting the findings of this study. In a previous study, social and religious activities decreased due to COVID-19 but did not affect the risk of developing depression [5]. In this study, approximately 61% of older people living alone without family members had an average depression score of 4.25±3.87, and about 60% of older people with mild depression corresponding to a score of 5 or higher. This is about twice as high as the average depression score of 2.76±2.43 for older people aged 60 years or older with osteoarthritis, and the depression rate was also 14.4% [17], which is the depression rate for older people with knee osteoarthritis and older people aged 65 years or older living in Turkey in 2015. The rate of depression is about 3 to 4 times higher than the target depression rate of 25.2%, hence an intervention plan through continuous psychological support for depression in older people after COVID-19 is needed. Therefore, Nursing education and interventions for older people in the community should be devised so that health behaviors and perceptions related to reduced physical activity can change during the COVID-19 period. A meta-analysis of sarcopenia interventions in older people showed that exercise improved strength, balance, and muscle mass [36]. However, the combination of protein supplementation and low-intensity exercise, which accounted for about 70% of women participants, was not effective for sarcopenia [37]. Additional research is needed. In future research, we recommend considering psychological factors when developing interventions to prevent sarcopenia and conducting comparative studies on the effectiveness of sarcopenia depending on the intensity of exercise.
The present study has several limitations. Firstly, since this was a cross-sectional study, caution is needed when interpreting the factors related to sarcopenia in older people in the community as a causal relationship between cause and effect. Secondly, since only older people in one community were targeted, there is a limit to extending the interpretation to the entire community. Thirdly, variables on food intake and diet, which are the major causes of sarcopenia, were not included. Therefore, we suggest the following for future research: Primarily, a study that expands the subject to represent older people in Korea and a study of sarcopenia targeting older people living alone or a study that includes the number of family members as a variable. Since the prevalence of sarcopenia in older people differs according to the diagnostic criteria and methods for sarcopenia, we suggest further research using various diagnostic criteria and methods is needed. Finally, follow-up studies including variables on protein intake, dietary form, and physical activity level, which are important causes of sarcopenia, are needed based on the literature.
CONCLUSION
In conclusion, among older people living in the community, the prevalence of sarcopenia among older women was six times higher than that among older men. The risk of sarcopenia, physical performance limitations, and depression is approximately five times higher in older adults aged ≥85 years. Therefore, measures to prevent sarcopenia in old women are urgently required. Since depression and physical performance are the main influencing Factors, we suggest the development of interventions to prevent sarcopenia in older people.
Declaration of conflict of interest: The authors declare no conflicts of interest.
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