Study design
Our study included 136 outpatients who visited the geriatric clinic in three months. To avoid confounding, 31 patients with known myositis, tendinitis, or disease in the muscle tendons, and a history of lower extremity surgery were excluded from the study. Additionally, 42 patients with advanced Alzheimer's disease, cerebrovascular disease, speech and language problems, systemic inflammatory disease, or lower extremity venous insufficiency were excluded. Of the remaining 63 patients, eight were lost to follow-up, and the final sample size was 55 patients. The patients’ sociodemographic data were recorded and a comprehensive geriatric evaluation was performed. The comprehensive geriatric evaluation comprised of the following tests: activities of daily living (ADL), instrumental activities of daily living (IADL), Mini Nutritional Assessment Test Short Form (MNA-SF), Geriatric Depression scale-15 (GDS-15), Mini-Mental State Examination (MMSE), and (SARC-F). The incidence of falls during the follow-up period was recorded. The presence of comorbid diseases and the number of drugs used were recorded. A radiologist who specialized in elastography, was an expert on the subject, and had performed several elastographies in the last five years performed the SWE examinations in our study. The radiologist was blinded to the patients’ details and fall history. After the baseline evaluations were performed, the patients were followed-up for six months. At the follow-up visit, the patients were interviewed in person and the number and incidence of falls during the six-month follow-up period was recorded. All patients were asked to record their falls in a diary and additional phone calls were made each month.
Components of the comprehensive geriatric assessment
1. Activities of daily living
This scale assigns one point for the adequate performance of each of six ADL functions including: bathing, dressing, toilet hygiene, mobility, incontinence, and feeding [15]. The overall ADL score between 0 and 6 is noted. The validity and reliability of the ADL scale in Turkish are reported by Gunes et al. [16].
2. Instrumental activities of daily living
The IADL scale measures an individual’s activity levels regarding phone use, shopping, meal preparation, house cleaning, laundry washing, transport, timely consumption of medications, and money management. The overall test score varies between 0 and 8, with lower scores indicating greater dependency [17]. The Turkish version of the IADL scale is validated [18].
3. Mini Nutritional Assessment-Short Form
This test is used for malnutrition screening, and the validity and reliability of its Turkish version have been reported [19, 20]. An overall MNA-SF score varies between 0 and 14. Scores ≤ 11 points indicate a risk for malnutrition [20].
4. Mini-Mental State Exam
The MMSE is commonly used for cognitive screening in older adults. The validity and reliability of this scale in Turkish has been reported. The overall MMSE score ranges between 0 and 30 [21, 22]. Scores ≤ 24 points indicate cognitive impairment [22].
5. Geriatric Depression scale-15
The GDS-15 evaluates depressive symptoms in older adults. Responses are scored between 0 and 15 and an overall score ≥ 5 indicates a risk of depression [23]. Durmaz et al. reported the validity of the Turkish version [24].
6. SARC-F
This scale, validated in Turkish by Güliastan et al., was recommended in 2018 for sarcopenia screening [25, 26]. The responses are scored between 0 and 10; scores ≥ 4 indicate sarcopenia that requires further investigation [26].
Muscle measurements
1. Handgrip strength
A digital handheld dynamometer (T.K.K.5401; Takei Scientific Instruments, Tokyo, JAPAN) was used to assess muscle mass. The patients were instructed to sit on a chair, extend their arms parallel to the ground, and squeeze the dynamometer with their dominant hand. This process was repeated thrice and the highest handgrip strength value was recorded. In the Turkish population, the cutoff values for handgrip strength are 22 and 32 kg for women and men, respectively [27]. For handgrip strength values below the cutoff values, the possibility of sarcopenia was investigated.
2. Evaluation of muscle thickness and elasticity
A single radiologist performed all the SWE examinations using an ultrasound system (LOGIQ E9; GE Medical Systems, Wisconsin, USA) with a 9-MHz linear transducer. The radiologist examined only the medial heads of the gastrocnemius and rectus femoris muscles bilaterally, with the patient in the prone position. The tip of the linear transducer was sufficiently covered with ultrasound gel. First, the medial head of the gastrocnemius and rectus femoris were scanned using B-mode imaging. The linear transducer was placed parallel to the longitudinal axis of the medial heads of both muscles. The thickest portion of each muscle was measured in millimeters. Thereafter, elastography imaging was performed in the same position, and particular attention was given to avoid applying any pressure to the skin. Shear wave elastography imaging was performed at the thickest portion of the medial heads of the gastrocnemius and rectus femoris. Stiffness values in kilopascals (kPa) were measured for the selected portions of these two muscles, whilst the muscles were in a relaxed state [28]. The examination was repeated for the other leg.
3. Muscle function assessment
The timed up and go (TUG) test is recommended by the European Working Group on Sarcopenia in Older People (EWGSOP2) to evaluate muscle function [29]. It is beneficial in measuring mobility and dynamic balance, and evaluating falls among older adults [30]. In the test, patients are asked to wear regular shoes, walk 3 meters away from a chair, then return to the chair, and sit. The total time elapsed determines the test result [30]. Bischoff et al. determined the TUG cutoff value for older adults as 12 s, which was used in our study [29].
Ethical approval
This study was performed in accordance with the Declaration of Helsinki and approved by the relevant ethics committee. Verbal and written informed consent were obtained from all the patients participating in the study.
Statistics
Categorical variables are expressed as numbers and percentages (n, %). Histograms and coefficients of variation were used to determine the distribution of the numerical parameters. Normally distributed numerical parameters are shown as mean ± standard deviation. Non-normally distributed numerical parameters are shown as medians (minimum – maximum). Student’s t-test was used to compare the numerical parameters showing a normal distribution between the two independent groups. Chi-square or Fisher's exact test was used to compare categorical variables. The comparison of non-normally distributed numerical data between the two groups was performed using the Mann–Whitney U test. Pearson's test was used to examine correlations between normally distributed numerical parameters, and Spearman's test was used for non-normally distributed numerical parameters. To interpret the Spearman or Pearson’s (r) coefficient, we used the following benchmarks: 0–0.20 = poor correlation; 0.21–0.40 = fair correlation; 0.41–0.60 = moderate correlation; 0.61–0.80 = substantial/strong correlation; and 0.81–1.0 = near-perfect correlation [30]. The parameters associated with the decline in handgrip strength within the six-month follow-up period were determined using univariate analysis, and those with p < 0.05 were included in the logistic regression analysis. The correlation matrix was evaluated and parameters with a high correlation were excluded from the regression analysis. The backward stepwise model was used; the omnibus test had p < 0.005, and the Hosmer-Lemeshow test had a p value of > 0.005.