Abstract
The prevalence of low handgrip strength and sarcopenia in people aged ≥65, in the Republic of Korea, was investigated using data from the Korea National Health and Nutrition Examination Survey (KNHANES). This study included participants in the 2022 KNHANES aged ≥65 years who had handgrip strength and muscle mass measured by bioelectrical impedance analysis, according to the Asian Working Group for Sarcopenia 2019 guidelines. In 2022, prevalence of low handgrip strength among those aged ≥65 was 14.2% for men and 18.8% for women, and the prevalence of sarcopenia was 6.6% for men and 9.2% for women. In this study, the prevalence of sarcopenia was higher in older age, women than in men, and low-income groups. In conclusion, older people and those with in low-income groups are vulnerable to sarcopenia; therefore, it is necessary to focus on early identification of sarcopenia and development of prevention and management intervention programs for these people.
Keywords: Sarcopenia, Handgrip strength, Korea National Health and Nutrition Examination Survey
Key messages
① What is known previously?
Sarcopenia is defined as the age-related loss of skeletal muscle mass, loss of muscle strength, and/or reduced physical performance, and it increases the risk of falls, fractures, and chronic diseases. In a previous study conducted in the Republic of Korea, the prevalence of sarcopenia was reported to be approximately 10%.
② What new information is presented?
The prevalence of sarcopenia was 6.6% in men and 9.2% in women and was higher in low-income groups.
③ What are implications?
Early identification of sarcopenia and development of prevention/management interventions for vulnerable groups, such as older people and individuals in low-income groups, are required.
Introduction
Sarcopenia is characterized by the loss of muscle mass associated with aging, as well as the decline in muscle strength or physical function [1]. The loss of muscle mass increases the risk of falls and fractures and the incidence of chronic diseases such as diabetes mellitus, high blood pressure, and cardiovascular disease [1-3]. The lower extremity muscle strength performance evaluated in the National Survey of Older Koreans was decreasing from 79.7% in 2014 to 78.6% in 2017 and 77.9% in 2020 [4-6]. Although a domestic study of community-dwelling people aged 70 years or older in 2016–2017 reported that the prevalence of sarcopenia was 14.4% in men and 6.4% in women, continuous trends in its prevalence have not been reported [7]. As sarcopenia is recognized as a disease, its disease code (M62.84) was registered in the World Health Organization’s 10th International Statistical Classification of Diseases and Related Health Problems code (ICD-10) in 2016. In the Republic of Korea (ROK), sarcopenia was also included as a diagnosis code (M62.5) in the 8th Korean Standard Classification of Diseases and Causes of Death (KCD-8) in 2021 [1]. The Korea National Health and Nutrition Examination Survey (KNHANES) has included measuring handgrip strength and published the distribution of handgrip strength in individuals aged 10 years or older since 2014, along with the prevalence of low handgrip strength in people aged 65 years or older according to the criteria of the Asian Working Group for Sarcopenia (AWGS 2019) since 2019 [1]. In 2022, the KNHANES introduced bioelectrical impedance analysis (BIA) to measure muscle mass and newly calculate the prevalence of sarcopenia. In this study, we investigated the prevalence of sarcopenia in the ROK based on the handgrip strength and muscle mass measurement data from the 2022 KNHANES.
Methods
1. Participants
The KNHANES is a nationwide health and nutrition survey to assess health status, health behaviors, and food and nutritional intake status of Koreans based on Article 16 of the National Health Promotion Act [8]. The target sample of the KNHANES was extracted to select primary sampling units (PSUs) and household members in the primary and secondary stages using two-stage stratified, clustered sampling. The participants in the KNHANES comprise approximately 192 PSUs every year, and all household members aged 1 year or older in 25 sample households per PSU. This study analyzed 2022 KNHANES participants aged 65 years or older who underwent handgrip strength (n=1,462) and body composition (n=1,276) analyses.
2. Methods
The health examination of the KNHANES was conducted at mobile examination centers by survey staff members from the Korea Disease Control and Prevention Agency. For measuring handgrip strength, the handgrip strength of both hands or one hand was measured twice using a digital grip dynamometer (TKK 5401; Takei), and a maximum value was used as the handgrip strength measurement. A visual examination and survey were conducted to select those who should be excluded from handgrip strength testing. Handgrip strength testing was not performed in people with visual examination items, such as defects in the arm/hand/thumb, hand paralysis, cast or bandage on the hand/wrist, or survey items, such as subjective inability to participate in the survey or worsening of pain/tingling/stiffness in the hands within the past 7 days.
Body composition analysis was performed to evaluate lean body mass, muscle mass (excluding bone mineral), body fat mass, body water, and whole-body phase angle using an impedance body fat analyzer (Inbody 970; InBody Co., Ltd.). Some participants with artificial pacemakers and implantable cardioverter defibrillators were excluded. Muscle mass (excluding bone mineral) was measured for each body part, and the sum of the limb muscle masses (right arm, left arm, right leg, left leg) was calculated.
3. Statistical Analysis
In this study, data were analyzed using a complex sample design analysis method that assigned sample weights to represent the Korean population using SAS (version 9.4; SAS Institute Inc.). The prevalence of low handgrip strength and sarcopenia were analyzed for only those aged 65 years or older who participated in the KNHANES and who had no missing data required for calculating the concerned indicators. The residential area was classified into dong (urban area), which is a lower administrative district of a city or district, and eup-myeon (rural area), which is a lower administrative district of a county. Household income levels were classified using the monthly equivalized household income (monthly household income/√ number of household members) into quintiles by sex and age (5-year units).
4. Definitions of Indicators
The prevalence of low handgrip strength was calculated as the percentile of those with a maximum grip strength value of <28 kg for men and <18 kg for women, among the values of handgrip strength, which were measured twice for both hands or one hand according to the criteria of the AWGS 2019 [1]. The prevalence of sarcopenia was also calculated as the percentage of those with correspondingly low handgrip strengths based on the criteria of the AWGS 2019, and the sum of all limbs muscle masses (excluding bone minerals)/height2 <7.0 kg/m2 for men and <5.7 kg/m2 for women in the results of impedance body fat analysis [1].
Results
1. Prevalence of Low Handgrip Strength
The prevalence of low handgrip strength among those aged 65 years or older was 16.7% (14.2% in men, 18.8% in women) as of 2022 and increased with age, reaching 40.1% in those aged 80 years or older (Table 1). For those under 75 years old, there was no remarkable sex difference, but for those aged 75–79 years or older, it was higher in women than in men. There was no difference in the prevalence of low handgrip strength in men with respect to residential area. However, the prevalence of low handgrip strength in women was higher in eup-myeon area residents (25.4%) than in dong area residents (17.0%). With respect to income levels, the prevalence of low handgrip strength was higher in low-income groups for both men and women, and it was more evident in women.
Table 1. Prevalence of low handgrip strength (2022)a).
| Variables | Total | Men | Women | |||||
|---|---|---|---|---|---|---|---|---|
| n | % (SE) | n | % (SE) | n | % (SE) | |||
| Total (≥65) | 1,462 | 16.7 (1.2) | 681 | 14.2 (1.5) | 781 | 18.8 (1.7) | ||
| Age (yr) | ||||||||
| 65–69 | 498 | 6.7 (1.4) | 233 | 6.8 (2.2)c) | 265 | 6.5 (1.7)c) | ||
| 70–74 | 390 | 12.9 (2.0) | 182 | 12.6 (2.9) | 208 | 13.2 (2.6) | ||
| 75–79 | 341 | 19.9 (2.3) | 161 | 15.5 (3.0) | 180 | 22.9 (3.4) | ||
| ≥80 | 233 | 40.1 (3.9) | 105 | 35.2 (5.8) | 128 | 43.3 (5.2) | ||
| Residential area | ||||||||
| Urban areas | 1,020 | 15.6 (1.4) | 475 | 13.8 (1.8) | 545 | 17.0 (1.9) | ||
| Rural areas | 442 | 21.1 (2.5) | 206 | 15.6 (2.7) | 236 | 25.4 (3.7) | ||
| Household incomeb) | ||||||||
| Low | 276 | 21.8 (3.0) | 129 | 16.0 (3.3) | 147 | 26.5 (4.7) | ||
| Low-middle | 289 | 20.4 (3.1) | 135 | 17.6 (3.9) | 154 | 22.9 (4.5) | ||
| Middle | 290 | 12.8 (2.3) | 137 | 11.7 (3.1)c) | 153 | 14.0 (2.9) | ||
| Middle-high | 302 | 15.1 (2.8) | 142 | 11.6 (2.6) | 160 | 18.1 (4.5) | ||
| High | 302 | 14.9 (2.6) | 138 | 14.9 (3.9)c) | 164 | 15.0 (3.3) | ||
SE=standard error. a)Cited from Korea Health Statistics 2022 [8]. b)The household income was calculated by dividing the household monthly income by the square root of the household size, and then categorized into quintile. c)Coefficient of variation: 25–50%.
2. Prevalence of Sarcopenia
The prevalence of sarcopenia in those aged 65 years or older was 7.9% as of 2022 and increased with age, reaching 7.1% in those aged 70–74 years, 9.9% in those aged 75–79 years, and 20.0% in those aged 80 years or older (Table 2). Its prevalence was higher in women (9.2%) than in men (6.6%), its prevalence in women aged 75–79 years was about twice as high as in men aged 75–79 years and was similar between men and women aged 80 years or older. With respect to residential areas, the prevalence of sarcopenia showed no difference in men. However, its prevalence in women was about twice as high in eup-myeon area residents (14.8%) than in dong area residents (7.7%). With respect to income levels, the prevalence of sarcopenia in both men and women was higher in the low (or bottom 40% of income earners) or lower-middle income groups.
Table 2. Prevalence of sarcopenia (2022)a).
| Variable | Total | Men | Women | |||||
|---|---|---|---|---|---|---|---|---|
| n | % (SE) | n | % (SE) | n | % (SE) | |||
| Total (≥65) | 1,276 | 7.9 (0.8) | 605 | 6.6 (1.0) | 671 | 9.2 (1.2) | ||
| Age (yr) | ||||||||
| 65–69 | 461 | 2.7 (0.8)c) | 220 | 2.2 (1.0)c) | 241 | 3.3 (1.2)c) | ||
| 70–74 | 343 | 7.1 (1.4) | 163 | 5.9 (1.9)c) | 180 | 8.1 (2.1)c) | ||
| 75–79 | 287 | 9.9 (1.7) | 133 | 6.6 (2.0)c) | 154 | 12.8 (2.8) | ||
| ≥80 | 185 | 20.0 (3.3) | 89 | 18.8 (4.5) | 96 | 21.2 (5.0) | ||
| Residential area | ||||||||
| Urban areas | 910 | 7.3 (1.0) | 428 | 6.8 (1.1) | 482 | 7.7 (1.4) | ||
| Rural areas | 366 | 10.4 (1.7) | 177 | 5.9 (2.1)c) | 189 | 14.8 (2.5) | ||
| Household incomeb) | ||||||||
| Low | 235 | 9.8 (2.0) | 110 | 8.2 (2.5)c) | 125 | 11.1 (2.7) | ||
| Low-middle | 254 | 13.8 (2.4) | 123 | 10.0 (3.0)c) | 131 | 17.9 (3.8) | ||
| Middle | 252 | 4.6 (1.2)c) | 121 | 4.2 (1.8)c) | 131 | 5.1 (1.8)c) | ||
| Middle-high | 271 | 5.6 (1.3) | 129 | 4.9 (1.7)c) | 142 | 6.2 (2.0)c) | ||
| High | 262 | 6.9 (1.9)c) | 122 | 6.5 (2.2)c) | 140 | 7.2 (2.5)c) | ||
SE=standard error. a)Cited from Korea Health Statistics 2022 [8]. b)The household income was calculated by dividing the household monthly income by the square root of the household size, and then categorized into quintile. c)Coefficient of variation: 25–50%.
Discussion
The prevalence of low handgrip strength among Koreans aged 65 or older was 16.7% (14.2% in men, 18.8% in women). The prevalence of sarcopenia was 7.9% (6.6% in men, 9.2% in women). The prevalence of sarcopenia was higher in women than in men and in those with low income.
The prevalence of sarcopenia varies from 10% to 27% depending on the methods to measure muscle mass and the criteria [9]. Although AWGS criteria are used, the calculated prevalence still vary with respect to measurement methods, for example, 18% in a study using dual-energy X-ray absorptiometry (DXA) and 14% in a study using BIA [9]. More so, the prevalence of sarcopenia also differs in the same participants with respect to the criteria other than the AWGS criteria [7,10].
The prevalence of sarcopenia in this study was 7.9%, which was lower than that reported in a meta-analysis study of Asians (15.0%) [9]. In another study that used BIA, the prevalence of sarcopenia in Asians (10% in men, 11% in women) was lower than that in non-Asians (Europeans, Americans, etc.) (19% in men, 20% in women) [11], and that in the ROK was even lower (6.6% in men, 9.2% in women). Regarding racial differences in the prevalence of sarcopenia, it has been suggested that the cutoff value for calculating the prevalence of sarcopenia in Asians is lower than that in Western societies and that sarcopenia was likely to be prevented in Asians by consuming healthier foods and engaging in more physical activity compared to people in Western societies [11].
By sex, the prevalence of sarcopenia in women was higher than that in men, and in those aged 70 years or older (AWGS 2019, DXA, and handgrip strength measurement) as reported in the results of the frailty cohort in the ROK, it was higher in men (14.4%) than in women (6.4%) [7]. However, a meta-analysis based on the AWGS criteria reported that the prevalence of sarcopenia in men and women was 14.0%, respectively, with no sex difference. Therefore, follow-up studies are needed to investigate study results in different directions according to sex [9].
By age, the prevalence of sarcopenia in women aged 75–79 years was higher than that of men of the same age group, but there was no significant difference in those aged 80 or older. In women, the secretion of sex hormones such as estrogen and androgen decreases after menopause, leading to loss of muscle mass, which increases the prevalence of sarcopenia in their 60s and 70s. Meanwhile, in men, the secretion of sex hormones (testosterone) decreases at a later age than women and its prevalence increases rapidly after the eighth decade of life [11].
The results of this study showed that the prevalence of sarcopenia differed according to income level. A study of people aged 65 or older in China reported that lower household income was associated with a higher prevalence of sarcopenia (based on AWGS 2019, muscle mass [BIA], and handgrip strength [3 measurements] or walking speed) [12], which was similar to the results of this study. A study of individuals aged 60–89 years living in rural areas in China suggested that the factors contributing to the higher prevalence of sarcopenia in those with lower income levels might be affected by the possibility that lower income levels might be associated with lower nutritional knowledge levels for health management [13]. A study involving middle-aged people in China stated that patients with sarcopenia in the low-income class might have increasing risk of catastrophic health expenditure, making it difficult for them to diagnose and manage sarcopenia [14].
Moreover, the results of this study showed that there was no significant sex difference in the prevalence of sarcopenia in dong area residents, but there was a distinct difference in its prevalence among eup-myeon area residents (5.9% in men and 14.8% in women). In a previous study of people aged 60–89 years living in rural areas of China (based on AWGS 2019, muscle mass [BIA] and handgrip strength [more than 2 measurements]) were also higher in women (21.7%) than in men (12.9%), which was similar to the results of this survey [15].
In conclusion, the results of this study suggest that the prevalence of sarcopenia in those aged 65 or older in the ROK is 7.9%, which is lower than in other countries [9]. However, this study suggests that sarcopenia increases with age, and, in particular, those with low income levels may be particularly vulnerable to sarcopenia. In the 5th Health Plan, public health centers’ home visiting health services for older adults, which were focused on managing chronic diseases, were reorganized into a universal healthcare service system for frailty and is promoting expansion of community support projects such as AI or IoT-based health service projects for older adults [16]. It is important to provide vulnerable groups such as low-income groups with priority early intervention such as early detection of sarcopenia, nutritional management programs (senior gathering programs at senior centers and welfare centers, home visit/delivery programs, cooking classes, etc.), and exercise programs. Along with handgrip strength measurement, the KNHANES plans to introduce DXA between 2024 and 2028 to measure muscle mass more accurately and monitor trends in sarcopenia and related factors accordingly.
Acknowledgments
None.
Declarations
Ethics Statement: This study was approved by the Institutional Review Board of Korea Disease Control and Prevention Agency, and all subjects provided written informed consent (IRB no. 2018-01-03-4C-A).
Funding Source: None.
Conflict of Interest: The authors have no conflicts of interest to declare.
Author Contributions: Conceptualization: DYK, KWO. Data curation: DYK. Methodology: DYK, KWO. Writing – original draft: DYK. Writing – review & editing: KWO.
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