This study showed that the prevalence of sarcopenia in the elderly in China was 28.8%, which was consistent with the results reported by Cruz-Jentoft et al[30]ranging from 1–29%.Sarcopenia can lead to limited mobility, increased risk of disability, falls, and death[31, 32].Therefore, identifying high-risk individuals is critical to prevent sarcopenia and related adverse outcomes.
This study shows that sex is a predictor of sarcopenia, and the research results show that sarcopenia is related to sex, and the male population is more frequently affected by sarcopenia, which is consistent with the results of previous studies[33, 34].The reason may be that sarcopenia is caused by genetic inheritance or gene mutation, as the causative gene is located on the sex chromosome, whereas in males there is only one chromosome, so one mutation is sufficient to cause the disease, whereas in females there are two chromosomes and mutations in two copies of the gene cause the disease, and it is rare for females to inherit two copies of the gene, so males are more likely to develop myotonic dystrophy than females[35].This is why men are more likely to develop dystrophy than women. There is no way to change the genes, whether they are inherited or mutated, but the disease can only be controlled by medication to slow down the progression, improve symptoms, improve muscle strength and prolong life expectancy.
Our study showed that BMI was also a predictor of sarcopenia, with the lower the BMI, the higher the risk of having sarcopenia, which is similar to the findings of Wu LC[36] et al. Therefore, it can be inferred that the higher the BMI, the better the prognosis for elderly. However, considering that being overweight in the elderly can lead to metabolic syndrome, this may place a physiological burden on the elderly. At the same time, metabolic disorders can lead to malnutrition, which in turn can create a vicious circle. A Meta-analysis of 26 studies showed[37] that the different training modes had significant effects on muscle strength and physical performance in elderly patients with sarcopenia. A systematic review showed that[38] appropriate physical activity can enhance muscle strength and flexibility, prevent muscle atrophy and degeneration, as well as improve blood circulation and metabolism, helping to maintain good health. In summary, physical activity has beneficial effects on muscle mass, muscle strength or physical performance in people aged 60 years and above[39].In addition, nutritional supplements can be effective in improving muscle mass and preventing the occurrence of metabolic syndrome. Selenium and magnesium have been studied as supplements in randomized controlled trials and observational dietary studies[40, 41], and appear to be potentially associated with physical activity and muscle performance in the elderly. Also, in randomized controlled trials[42], omega-3 fatty acids have repeatedly demonstrated value in maintaining muscle mass and preventing normal decline in older people. Therefore, older adults at risk of muscle loss should be provided with early nutritional interventions and muscle exercises to reduce the risk of sarcopenia.
The study also found that blood pressure was strongly associated with the development of sarcopenia, with high systolic blood pressure possibly reflecting vascular stiffness, which may reduce the ability of blood flow to the muscles, resulting in insufficient nutrient supply to the muscles, thereby increasing the risk of sarcopenia; low diastolic blood pressure may indicate that the heart is unable to adequately supply the body with blood during diastole, which may likewise affect the nutrient supply to the muscles, which may also affect nutrient supply to the muscles[43].High systolic blood pressure and low diastolic blood pressure may be the signs of the decline of body function in the elderly, and the decline of body function is closely related to sarcopenia. Therefore, in the future, in addition to paying attention to the heart, brain and kidney complications brought by hypertension patients, we should also pay attention to the loss of muscle.
In addition, this study shows that pain is also associated with sarcopenia, which has a crucial impact on spinal health as the maintenance of spinal function requires the involvement of strong low back muscles. On the one hand, the number and quality of muscles decline, so that the muscle tolerance to strain is reduced, the muscle is more prone to fatigue, its ability to maintain the overall stability of the spine decreases, spine instability greatly increases the incidence of chronic low back pain; On the other hand, the function of the trunk muscles, especially the function of the dorsal extensor group, is reduced, resulting in weak muscle suspension of the spine, and it is difficult for the body to maintain a normal upright posture, resulting in severe leaning forward. However, the posture of leaning forward will increase the work done by the muscles in the rear, fatigue the muscle tissue, and make it impossible to maintain the body upright, resulting in a vicious cycle and affecting the quality of life of patients[44]. Therefore, the prevention and treatment of sarcopenia is a very important and urgent problem for the spine health of the elderly.
On the basis of multi-factor regression analysis, the column chart integrates multiple prediction indicators, and then uses line segments with scales to draw on the same plane according to a certain proportion, so as to express the relationship between various variables in the prediction model. It can be used to predict the probability of clinical outcome events by combining scores for each predictor to obtain an overall score. It is a common predictive model used in research in many clinical fields. In this study, we found that Sex, BMI, MSBP, MSBP and Pain were the main predictors of sarcopenia in older Chinese people. Our predictive model was constructed based on these five factors that influence the development of frailty and showed good discrimination, calibration and clinical validity, indicating that the predictive model is valuable for effectively identifying older adults at high risk for sarcopenia. The column chart can specifically quantify the hazard ratio in the form of scores, and the probability of certain outcomes for patients can be obtained through simple calculation, and personalized risk assessment can be provided for each individual with high relevance and accuracy. Therefore, the development of a predictive model for sarcopenia in the elderly is a new achievement of this study. As a highly efficient and accurate assessment tool, our predictive model can help physicians to screen older adults at risk for sarcopenia and provide a theoretical basis and entry point for developing early prevention and intervention measures. The predictive model has good clinical applicability and can help screen patients at high risk of sarcopenia.
There are some limitations to this study. First, some potential predictors were not provided in the CHARLS database, including potential factors such as dietary habits, nutritional status, and so on. Secondly, the nomogram was developed based on data from China, and whether the results of this study can be generalized to other regions and countries requires further analysis using externally validated data. Third, this was a retrospective study with no follow-up of this population, so more data from patients who received long-term follow-up should be analyzed to improve the current nomogram model.