In this study, we estimated the pooled prevalence and risk factors of sarcopenia among Chinese MHD patients. Of total 28 articles were identified, with 6123 patients. In this meta-analysis, the pooled prevalence of sarcopenia in Chinese MHD patients was 29.0% (95% CI: 25.0–32.0%), which was higher than the overall prevalence of sarcopenia in older Chinese adults (14%, 95%CI: 11.0–18.0%)[22]. It indicates that MHD patients are more likely to experience sarcopenia than general elderly patients. However, high heterogeneity exists between studies, and univariable meta-regression showed that mean age accounted the overall heterogeneity.
Subgroup analyses found that the pooled incidence of sarcopenia among Chinese MHD patients with increasing age, which was the most common cause of sarcopenia[23]. It’s widely known that sarcopenia is an age-related syndrome and skeletal muscle tissue, physical activity and physical function often decrease with age. A new meta-analysis in community-dwelling older adults showed that the prevalence of sarcopenia was associated with age (OR = 1.12, 95%CI: 1.10 to 1.13).23 Previous studies also revealed that physical activity and physical function protected against sarcopenia[49, 50]. However, apart from age, physical activity and physical function, MHD patients more likely to suffered from poor nutrition, inflammation, cognitive impairment and diabete compared with the general population, which lead to MHD patients being more susceptible to experiencing sarcopenia[51–54]. Given that the prevalence of sarcopenia is related to age, a higher incidence could be expected in future research involving elderly MHD patients.
Subgroup analyses showed that the prevalence of sarcopenia in MHD patients decreased with increasing sample size. Smaller sample groups (31.8%) were higher than moderate sample groups (26.8%), which significantly higher than larger sample groups (16.9%). Sample size affects selection and publication bias, contributing to more extreme prevalence estimates[55]. Therefore, optimal sample sizes need to be carefully considered in the future study.
Meta-analyses revealed that age, BMI, dialysis duration, hs-CRP, MQSGA score,upper arm circumference and gender were significantly associated with sarcopenia in Chinese MHD patients. Our result demonstrated that BMI and upper arm circumference were protective factors for sarcopenia and for every 1 kg/m2 increased in BMI, the odds of sarcopenia decreased by a factor of 0.67. MQSGA, with higher score indicating lower nutritional status, was the risk factor for sarcopenia, and for every 1 point increased in MQSGA score, the odds of sarcopenia increased by a factor of 1.75. However, BMI, upper arm circumference and MQSGA score all indicate the presence of nutrition. Special diet restriction, hemodialysis treatment, and uremic substance-included central loss of appetite cause MHD patients to be liable to protein-energy wasting (PEW), defined as inadequate protein and energy intake, which was associated with sarcopenia[56, 57]. Previous studies also demonstrated that nutrition supplementation contributed to improving muscle mass and strength[58]. Our study found that high levels of hs-CRP, a marker of low-grade chronic inflammation, increased the risk of sarcopenia, which was often used to evaluate the inflammation state in clinical practice. Inflammatory cytokines could stimulate protein catabolism and suppressing muscle synthesis, resulting in muscle wasting[59]. Dialysis duration was considered as the risk factor for sarcopenia among MHD patients in this study. With longer dialysis duration, MHD patients are more susceptible to suffering from malnutrition, inflammatory stimulation, hormone imbalance and glycogen ect., all of which may increase the rate of sarcopenia. This study also found that male as a risk factor for sarcopenia, which might be because male MHD patients are more prone to hypogonadism, resulting in low testosterone[60]. Study has demonstrated that testosterone as a centre hormone contributed to increasing muscle mass and muscle function[61]. Therefore, this result need to be explore in future study due to the limited number of studies.
LIMITATIONS
To our knowledge, this meta-analysis is the first study to explore the pooled prevalence and risk factors for sarcopenia in Chinese MHD patients. However, some limitations should be acknowledged. First, high heterogeneity is observed between studies, which indicates the results need to be interpreted with caution. Second, some small sample sizes and a lack of high-quality records were included in this study. Both of them may increase the risk of bias in this review. Third, no grey literature is searched, which may lead to a relatively high publication bia in this study. Finally, the combination of some risk factors may lack representation for sarcopenia in Chinese MHD patients due to the limited number of studies.