2. 1 Study subjects
This study was a controlled observational study conducted in accordance with the Declaration of Helsinki. It was reviewed and approved by the Medical Ethics Committee of Hunan Provincial People's Hospital (approval number: LL-20250517-457). As this was not a prospective intervention study, no clinical study lot number was requested. All participants signed written informed consent.
Patients who were hospitalized in the Department of Geriatrics of our hospital from November 2021 to January 2023 and voluntarily underwent sarcopenia screening were selected. Inclusion criteria: (1) age ≥60 years old; (2) able to independently complete all motor function assessments required for sarcopenia screening; (3) be conscious and able to complete the questionnaire; Exclusion criteria: (1) Recent conditions that may cause drastic changes in body composition, such as acute systemic infection, electrolyte disturbance, massive blood loss, etc. (2) acute or chronic organ failure; (3) patients with stroke or hemiplegia cannot independently complete motor function assessment; (4) Unable to complete the questionnaire independently. After strict screening according to the inclusion and exclusion criteria, the AWGS (Asia Working Group for Sarcopenia) 2019 diagnostic consensus (AWGS2) was used as the “gold standard” [13], and all enrolled patients were divided into the sarcopenia group and the non-sarcopenia group.
2. 2 Equipment and Methods
2. 2. 1 Clinical data collection
All patients were informed about the content and methods of the study and signed an informed consent form before participating in the study. The same physician measured the height and weight of the patients on the day of hospitalization, recorded their age and other basic clinical information, and drew venous blood from the patients early in the morning before the start of the treatment to test the biochemical indexes: albumin(ALB), triglyceride(TG), and so on.
2. 2. 2 Basic Information Questionnaire
A questionnaire survey was conducted in the awake state of the patients, and the intake of eggs and meat, and the number and duration of weekly exercises were recorded. The questionnaire was developed by us according to the research needs (shown in supplemental material 1).
2. 2. 3 HGS ( hand grip strength ) measurement
The patient was instructed to stand in a position with the shoulders retracted, the upper arms close to the median axillary line, the elbows flexed at 90 degrees, the long axis of the upper arms perpendicular to the floor, and the long axis of the forearms parallel to the floor. The data were read when the patient held the force surface of the grip strength device (RL-PG-07 from Guangzhou, China) with the dominant hand and tightened the handle device to the maximum extent. A total of 3 measurements were made and the maximum value was recorded.
2. 2. 4 Gait speed (GS) measurement
Measure the length of 6 meters on a flat, clean, and unobstructed ground, mark the starting point and the endpoint, ask the patient to walk as fast as possible from the starting point to the endpoint without slowing down in the middle, and use a stopwatch to record the time needed, test twice in total and take the average value.
2. 2. 5 Skeletal muscle mass was measured by Bioimpedance analysis(BIA)
The skeletal muscle mass of the patients was measured using a Korean Jevon IO1 human tissue composition analyzer. During the examination, patients removed their shoes and socks after urination, took off their metal jewelry, stood calmly, and held the handle of the instrument with both hands to ensure that the skin on the soles of the feet and palms of the hands was in direct contact with the electrodes of the feet and the handle. The patient's legs were slightly spread to ensure that the skin of the inner thighs did not come into direct contact with the electrodes, and the patient remained calm and did not move until the machine indicated that the measurement had been completed, obtaining the patient's body weight, fat mass, defatted mass, and muscle mass of the limbs.
Body Mass Index (BMI) and Fat-Free Mass Index (FMI) were calculated according to the formula BMI / FMI = body weight or fat-free mass (kg) / height (m) 2, and the unit was kg/m². Appendicular Skeletal Mass (ASM) was obtained by summing the muscle mass of the skeletal muscles of the extremities measured by BIA. Skeletal Muscle Mass Index (SMI) is obtained by dividing ASM (kg) by the square of height (m) in kg/m².
2. 2. 6 Ultrasonic measurement
Mindray M9 ultrasound instrument (Myriad Medical International Ltd, Shen Zhen, China) was used to measure the muscle thickness (MT) of bilateral brachioradialis (BR), vastus medialis(VM), gastrocnemius medial head(Gmh) and gastrocnemius lateral head(Glh) in the resting state of patients with L12-4 high-frequency superficial probe.
Muscle measurement methods
1. Brachioradialis(BR): The patient was placed in the supine position with the hands flat on either side of the body, palms naturally facing upward, and the probe was placed in the proximal 1/3 of the radius between the radial head and the condylar eminence of the carpal tunnel, with the long axis of the probe perpendicular to the long axis of the forearm. The MT of the BR was measured by scanning over an area of 6 centimeters above and below the BR, taking the largest cross-section of the BR(as show in Figure 1).
Figure 1: Measurement of BR MT (B: brachioradialis muscle, R: radius)
2. Vastus medialis (VM): the patient lies supine with the knee bent at 120° and the legs slightly separated. The probe was placed horizontally at the distal 1/3 of the inner thigh, and the scanning range was 6cm up and down. The MT of the VM was measured at the maximum cross-section(as show in Figure 2).
Figure 2: Measurement of VM MT (V:Vastus medialis muscle, F:Femur)
3. Gastrocnemius medial head(Gmh) and Gastrocnemius lateral head(Glh): the patient lies in the supine position with both knees bent at 120 degrees and legs slightly separated by 30 degrees—probe on the lateral and medial crus, popliteal fossa proximal 1/3, and tibial articular surface level. The longitudinal axis of the probe was perpendicular to the long axis of the calf. The scan range was 6 cm above and below, and MT was measured at the thickest point of the Glh and Gmh(as show in Figure 3).
Figure3: Measurement of Gmh MT ( G: gastrocnemius medial head, S: Soleus )
4. Calf muscle maximum circumference(CMMC): Select the C5-1 abdominal probe and extend it to the maximum imaging angle, with the probe perpendicular to the skin. Take the largest cross-section of the calf muscle group and track the trajectory along the outer edge of the calf muscle group to measure the CMMC(as show in Figure 4).
Figure 4: Measurement of CMMC. The white line was the trajectory depicted when the maximum circumference was measured around the periphery of the calf muscle using the trajectory method.
2. 2. 7 Quality control
1. All instruments are calibrated before use to ensure optimal functioning. 2. questionnaires were conducted and recorded by the same trained professional to ensure consistency. 3. all ultrasound images are captured and stored by a physician trained in musculoskeletal ultrasound with at least one year of experience in diagnostic ultrasound to ensure standardization of sections and clear imaging. 4. During the ultrasound procedure, a thick layer of coupling agent is applied between the probe and the skin to prevent external forces from interfering with the imaging. 5. Ultrasound data are averaged by the same sonographer after three repeated measurements on the stored images, retaining one decimal place.
2. 2. 8 Diagnostic criteria
The consensus for the diagnosis of Sarcopeniarecommended by the Asia Working Group for Sarcopenia in 2019 ( AWGS2) was used as the "gold standard" for this study. For details, see the figure:
(1) SMI ≤7.0 kg/m2 in men and ≤5.7 kg/m2 in women (measured by BIA);
(2) HGS < 28 kg in males and < 18 kg in females;
(3) GS < 1.0 m/s;
If it was 1+2/3, it could be judged as sarcopenia, and all patients were divided into the sarcopenia group and the non-sarcopenia group.
2, 3 Statistical methods
SPSS 26.0 software was utilized for conducting statistical analysis. The Shapiro-Wilk test was employed to assess the normality of the data distribution. In cases where the data followed a normal distribution, intergroup comparisons were performed using an independent t-test. For non-normally distributed data, non-parametric tests were applied for comparison purposes. Frequency was used to express count data, and group comparisons were analyzed using the chi-square test. Univariate and multivariate logistic regression analyses were conducted to identify independent predictors of sarcopenia in hospitalized elderly patients, leading to the development of a predictive model. The predictive performance of individual predictors and the model was evaluated through receiver operating characteristic (ROC) curves analysis. Statistical significance was defined as P<0.05.