Associations between the quality of life in sarcopenia measured with the SarQoL® and nutritional status

The subjects of this study were those who visited a health care center or a senior welfare center among the aged 65 years or older living in a community in two counties (Jinju, Sacheon), and the survey was conducted from April to August 2019. Among them, those with cardiovascular disease, cognitive disorder, or malignancy were excluded.

All surveys were conducted on a one-on-one basis after trained researchers interviewed subjects, explained the content of the survey, and obtained written informed consent from the subjects. In addition, this study was approved by the Institutional Review Board of Gyeongsang National University (Approval Number: GIRB-A19-0031).

Demographic characteristics for investigation were sex, age, living alone, educational level, smoking, and patient health questionnaire-2 (PHQ-2) survey for depressive symptoms that were thought to be associated with sarcopenia and nutritional status. After the survey, the education level was categorized into primary school level and more than only primary school level. In addition, those with a score of 3 or more on the PHQ-2 were considered to likely have depressive symptoms [11].

To determine the nutritional status of elderly participants, a questionnaire screening tool called DETERMINE was used [12]. This auto-administered questionnaire consists of 10 questions, with the name, DETERMINE, referring to an alphabetic collection of the first letters (in English) of each item assessed. Thus, questionnaire items consist of Disease, Eating poorly, Tooth loss, Mouth pain, Economic hardship, Reduced social contact, Multiple medicines, Involuntary weight loss or gain, Need for assistance in self-care, and Elderly [people] over 80 years old.

Weights are assigned according to importance. Nutritional risk scores were divided into 0–21 points, with 0–2 points categorizing the low-risk group, 3–5 points for the moderate-risk group, and 6 points for the high-risk group.

Specialized questionnaire tools have been developed and used to assess health-related quality of life (QOL) in older people as their muscle strength deteriorates [2]. The SarQoL questionnaire consists of seven domains and assesses quality of life in physical, mental, and social areas in the context of sarcopenia [2, 3]. This questionnaire is used to assess quality of life following intervention for sarcopenia, as well as health-related QOL in living with the condition.

Developed as a health-related quality of life tool for sarcopenia, the SarQoL questionnaire consists of 55 items and 22 questions. The questionnaire calculates a total 7 domain scores and a total score, each between 0 and 100 points.

Domain score are 0–100, items are (mostly) likert scales. The domains (enumerated 1–7) and items are as follows: (1) physical and mental health, assessed with eight items, such as loss of arm strength or feelings of being frail, (2) locomotion, assessed with nine items, such as limitations in walking time and difficulty in walking on uneven ground, (3) body composition, assessed with three items, such as loss of muscle mass, (4) functionality, assessed with 14 items, such as balance problems and frequency of falls, (5) activities of daily living, assessed with 15 items, such as difficulty during light physical effort, fatigue during light physical effort, and use of public transportation, (6) leisure activities, assessed with two items, such as changes in leisure activities, and (7) feelings of fear, assessed with four items, such as fear of getting hurt and fear of falling [3, 13].

The SARC-F questionnaire was developed for screening sarcopenia in the elderly. Question items consist of five categories of strength, assistance required for walking, rising from a chair, climbing stairs, and frequency of falls. Sarcopenia is suspected in patients receiving 4 points or more.

Calf circumference qualified participants for the sarcopenia (robust vs low) risk group with a cut-off point less than 34 cm for men and less than 33 cm for women [9].

The skeletal muscle index (SMI) was calculated using the following bioelectrical impedance analysis (BIA) regression equation (measured by InBody 720, Biospace Co., Ltd., Seoul, Korea): skeletal muscle (kg) = [0.401 × (height²/resistance) + (3.825 × sex) − (0.071 × age) + 5.102]. Low muscle mass was classified as a height-adjusted SMI value < 5.7 kg/m² for women and < 7.0 kg/m² for men [9].

Grip strength was measured using a smedley dynamometer (TK 5001 Grip-A, Takei, Tokyo, Japan), and dominant hand grip strength was classified as “robust” if the value was over 28 kg for men and over 18 kg for women [9].

To measure physical performance using the timed up and go (TUG) test, each individual was asked to stand from a sitting position, walk 3 m, and then return to a sitting position on the same chair, during which a trained researcher measured the time (in seconds) required to perform this task. Times were divided into robust and low level based on a baseline of 10 s [14].

The results were expressed as the median (percentile, 25 and 75) for those that did not followed a normal distribution. The normality of the variables was checked by a Kolmogorov–Smirnov test. Frequencies (N, %) were described for qualitative variables.

Study participants comprised 324 individuals living in six rural villages, and research was conducted at senior and welfare centers. All participants aged 65 years who lived in villages and were able to move to senior and welfare centers were surveyed. Of a population of 351 elderly people, 341 responded that they did not suffer from cognitive impairment, cancer, stroke, or myocardial infarction. A total of 324 participants was finally included in the investigation (341 healthy respondents, excepting 17, who declined to consent to participation).

The median (percentile 25 and 75) age of study subjects was 72.0 (68.3, 78.0) years, with women comprising 283 (87.3%) of total subjects. Of the elderly subject sample, 47.5% lived alone and 31.2% had depression. Skeletal muscle mass, calf circumference, grip strength, and TUG decreased in 11.1%, 43.5%, 21.9%, and 30.9% of all subjects, respectively. In terms of nutritional assessment, the low-risk group comprised 42.6%, the moderate-risk group comprised 29.3%, and the high-risk group comprised 28.1% of the sample. The overall (median (percentile of 25, 75)) of SarQoL was 70.2 (56.0, 81.8), among the sub-domains, physical and mental health had the lowest quality of life scores (62.2 (51.4, 76.6)), and fears were the highest (87.5 (75.0, 100.0)) (Table 1).

To evaluate the association between SARC-F and sarcopenia assessment, nutritional status, logistic regression analysis was performed. Among the assessment tools for evaluating sarcopenia, calf circumference (OR = 2.150, 95% CI = 1.057–4.376, p = 0.037) and TUG (OR = 3.414, 95% CI = 1.710–6.816, p = 0.001) showed statistically significant (Table 2). SARC-F and nutritional status (Determine ≥ 6 vs. < 3) were statistically associated (OR = 3.703, 95% CI = 1.580–8.682, p = 0.003).

Total score of SarQoL was significant in relationship to SARC-F (B = − 13.314, p < 0.001), grip strength (B = − 3.866, p = 0.034), and TUG (B = − 5.459, p = 0.001). The relationship between total score of SarQoL and nutritional status was significant in the moderate-risk group (B = − 5.542, p = 0.001) and in the high-risk group (B = − 8.136, p < 0.001) in comparison to the low-risk group (Table 3).

Relationships between physical and mental health and nutritional status were statistically significant in the moderate-risk group (B = − 4.353, p = 0.033) and in the high-risk group (B = − 7.013, p = 0.002) in comparison to the low-risk group. Trends were shown in locomotion (moderate-risk group (B = − 6.127, p = 0.026) and high-risk group (B = − 14.801, p < 0.001)), body composition (moderate-risk group (B = − 4.924, p = 0.019) and high-risk group (B = − 5.670, p = 0.017)), functionality (moderate-risk group (B = − 5.542, p = 0.012) and high-risk group (B = − 7.480, p = 0.003)), activities of daily living (moderate-risk group (B = − 5.857, p = 0.002) and high-risk group (B = − 5.287, p = 0.014)), and leisure activities (moderate-risk group (B = − 8.662, p = 0.004) and high-risk group (B = − 14.943, p < 0.001)). In particular, leisure activities were only significantly related to nutritional status. However, SARC-F was significantly related to physical and mental health (B = − 11.741, p < 0.001), locomotion (B = − 16.935, p < 0.001), body composition (B = − 9.124, p < 0.001), functionality (B = − 13.897, p < 0.001), and activities of daily living (B = − 14.336, p < 0.001). Findings from TUG tests were significantly related to locomotion (B = − 8.010, p = 0.001), functionality (B = − 6.869, p = 0.002), and activities of daily living (B = − 7.210, p < 0.001). In addition, grip strength was significantly related to activities of daily living (B = − 5.103, p = 0.014) and feelings of fear (B = − 7.243, p = 0.001). However, there were no SarQoL domains related to limb muscle mass or calf circumference.