This study was performed using the baseline data of Namgaram-2, which was developed to study the relationship between the prevalence of musculoskeletal disorders and activity limitations in the older adults in 6 rural villages. [14, 15]
At the time of the study, subjects who were diagnosed with chronic diseases and are currently receiving cancer treatment were excluded from the study. Only those with no cognitive problems were included in the study. The cognitive performance evaluation for participants with no cognitive function disorders was performed via an interview study utilizing the Korean version of the Mini-Mental State Examination for Dementia Screening (MMSE-DS). All surveys were evaluated by a medical professional.
After providing written informed consent, participants completed a questionnaire to assess cognitive function. Subsequently, fasting blood samples were collected from participants, followed by physical function evaluation. Among the 1,010 surveyed subjects, 885 were 60 years or older and had all necessary tests performed. These 885 population were selected as study subjects
All investigations were conducted after obtaining participant consent and after being reviewed by the Institutional Review Board of our institution (approval number: GIRB-A16-0012).
Data on social demographic variables such as gender, age, marital status, economic level perceived by the person, and health behavior variable such as smoking was acquired. Also, survey results, such as one on whether or not the subject was affected by hypertension and diabetes, were used. In addition, the blood test measured hemoglobin, cholesterol, albumin, uric acid, γ-GTP, and creatinine.
1) Frailty (Kaigo-Yobo checklist in Korean older adults)
The Kaigo-Yobo checklist was developed by researchers at the Tokyo Senior Research Institute, and the reliability and validity in Korean older adults have been confirmed. The checklist consists of 15 questions and is a survey instrument that focuses on social activities and evaluation of daily life. The Kaigo-Yobo checklist is a complex domain phenotype aging assessment tool and comprises questions only. The checklist’s 15 items consist of four products for nutritional status; three items for fall; two items for activities; two items for social relationships; and one item each for general health status, communication, mobility, and leisure activities. Furthermore, the appropriate answer to each query was 'Yes' or 'No,' and a score of one point was possible for each query. The final score is in the range of 0-15 points, and the higher the score was indicated the higher the degree of frailty.
The World Health Organization (WHO) developed the WHO Disability Assessment Schedule (WHODAS) based on the International Classification of Functioning, Disability, and Health (ICF). WHODAS-12 measures the difficulties caused by health conditions by dividing the difficulties into six areas (cognition, mobility, self-care, getting along, life activities, and participation).
All questions were measured with a 5-point Likert item system (1 point, not very difficult to 5 points, very severe). The final score is in the range of 0-100 points, and the higher the score, the higher the degree of disability in everyday life.
3) Depressive symptoms
To understand the symptoms of depression in the older adults, the Geriatric Depression Scale-Short Form-Korean (GDSSF-K) adapted and developed for aged people in Korea was used. The GDSSF-K has the advantage of comprising items that are easy for the older adults to understand relative to other current depression measurement tools. This scale of 15 items is graded from 0 to 15 points; higher values indicate worse depression.
Although several criteria have been proposed to define sarcopenia, the recent criteria of the Asian Working Group for Sarcopenia (AWGS 2019) were applied in this study. 
Dual energy X-ray absorptiometry (DEXA) was used to measure muscle mass. In addition, the measured total appendicular skeletal muscle mass (ASM), excluding bone and fat, divided by the square of the height (m2) was calculated (ASM/Ht2) and used as the skeletal muscle mass index (SMI). Sarcopenia was defined as SMI less than 7.0 kg/m2 in men and less than 5.4 kg/m2 in women. Muscle strength was evaluated by grip strength, and the measurement was conducted using the Smedley-type dynamometer (TKK 5401; Takei Scientific Instruments Co., Tokyo, Japan). Both hands were evaluated, twice each. Grip strength was used for analysis as one of the four measured values. The maximum value was used as a reference level, for men below 28 kg and for women below 18 kg.
Osteopenia was measured using data from dual energy X-ray absorptiometry (DEXA) and osteopenia was diagnosed when the T-score was less than -1.0.
The study subjects were divided into four groups : the normal group, in which both sarcopenia and osteopenia were undiagnosed, and the osteosarcopenia group, which was subdivided into those diagnosed with both sarcopenia and osteopenia, osteopenia only, and sarcopenia only.
The general characteristics of the participants generated descriptive statistics; the chi-square test was conducted on categorical variables, and the ANOVA test was performed on continuous variables. Post-hoc analysis was performed using the Tukey method. The odds ratios (OR) of osteosarcopenia prevalence according to socioeconomic status were analyzed by logistic regression.
The comparison of WHODAS, Kaigo-Yobo, and GDSSF values among the four groups of study subjects occurred after adjustment for gender, age, marital status, economic level, smoking status, hypertension, diabetes, hemoglobin, uric acid, albumin, r-GTP, creatinine, and cholesterol. [24–26] Adjusted means and their 95% confidence intervals (CIs) were estimated by general linear model (GLM) and the post-hoc test is based on Turkey method. And Partial eta squared (ηp2) was calculated to determine the effect size, using the 0.0099, 0.0588, and 0.1379 considered as small, medium, and large effect sizes. The SAS Version 9.4 program (SAS Institute Inc., Cary, NC) was used as the analysis tool, and the significance level was set to 0.05.