Computed tomography-determined skeletal muscle density predicts 3-year mortality in initial-dialysis patients in China

Association of Muscle Radiodensity and Muscle Mass With Thoracic Aortic Calcification Progression in Dialysis Patients

BACKGROUND

Recent findings have spotlighted sarcopenia as a critical factor exacerbating cardiovascular risk in dialysis patients. However, no studies have investigated the relationship of muscle characteristics with thoracic aortic calcification (TAC). We explored whether skeletal muscle radiodensity (SMD) and skeletal muscle index (SMI) are associated with TAC in dialysis patients.

METHODS

In this study, 2517 dialysis patients (between January 2020 and June 2023) from four centres with chest computed tomography (CT) scans were analysed cross-sectionally. A cohort of 544 initial-dialysis patients (between January 2014 and December 2020) was followed for TAC progression. Chest CT images were used to assess SMD and SMI at the L1 level, as well as to measure the scores of TAC, including ascending TAC (ATAC), aortic arch calcification (AoAC) and descending TAC (DTAC). Multivariable linear regression models were employed to assess the effects of SMD and SMI on TAC and its progression. Restricted cubic spline was used to assess the potential non-linear relationships of SMD and SMI with TAC progression.

RESULTS

The mean (SD) age for the cross-sectional study was 54.8 (14.0) years, with males accounting for 58.2%. Over a mean (SD) follow-up duration of 3.45 (1.82) years, 85.7% showed TAC progression. Comparing the highest quartile of SMD to the lowest quartile, a significant inverse association was observed with TAC (β, -1.08 [-1.42 to -0.75]; p < 0.001); similar trends were noted for SMI (β, -0.42 [-0.74 to -0.10]; p = 0.011). SMD and SMI as continuous variables were also both significantly negatively correlated with TAC. In the longitudinal study, multivariable linear regression models revealed that an increase of 1 SD in SMD resulted in a decrease of 0.10 SD (95% CI, -0.17 to -0.02; p = 0.011) in TAC progression, and an increase of 1 SD in SMI resulted in a decrease of 0.12 SD (95% CI, -0.20 to -0.04; p = 0.003) in TAC progression. Restricted cubic spline models excluded non-linear trends for the relationships of SMD and SMI with TAC progression. The associations of SMD and SMI with DTAC were consistent with those observed for TAC, but neither showed a significant association with ATAC.

CONCLUSIONS

Higher SMD and higher SMI were significantly associated with lower TAC and its progression in dialysis patients. Improving SMD and SMI could be a new approach for reducing TAC.

The chest CT perspective on sarcopenia: Exploring reference values for muscle mass quantity/quality and its application in elderly adults

OBJECTIVE

To determine reference values for diagnosing sarcopenia through chest CT scans and evaluate their suitability for use among the Chinese elderly population.

METHODS

Chest CT scans were obtained from 500 healthy individuals aged 19-39. Skeletal muscle mass was assessed on chest CT at the level of T4 by the skeletal muscle area (T4SMA), skeletal muscle index (T4SMI), T12 erector spinae muscle area (T12ESMA), and T12 skeletal muscle index (T12SMI), as well as skeletal muscle density (SMD) at T4 and T12 levels. The diagnostic threshold for sarcopenia was defined as a gender-specific value below 2 SD of the mean value in the young group. These cutoff values were then applied to a group of older adults aged 65 and over.

RESULTS

Diagnostic thresholds for low skeletal muscle in men were 110.05 cm², 36.01 cm²/m², 29.56 cm², and 9.65 cm²/m² for T4SMA, T4SMI, T12ESMA, and T12SMI, respectively. For women, the thresholds were: 69.93 cm², 26.51 cm²/m², 17.84 cm²/m², and 6.87 cm²/m², respectively. Diagnostic thresholds for low SMD were 38.63HU in men, 34.74 HU for women at T4 level. At T12 level, the cutoff values were 40.94 HU for men and 36.63 HU for women. Sarcopenia prevalence in men, defined by T4SMA, T4SMI, T12ESMA, and T12SMI cutoffs, was 35.6%, 18.9%, 36.7%, and 23.7%, respectively. In women, sarcopenia prevalence was 5.1%, 3.2%, 3.2%, and 1.9%, respectively.

CONCLUSION

This study established reference values for sarcopenia diagnosis through chest CT scans among the Chinese population, highlighting the importance of utilizing chest CT scans for sarcopenia detection and muscle health monitoring in older adults.

The gut microbiome, chronic kidney disease, and sarcopenia

Sarcopenia is a prevalent condition in patients with chronic kidney disease (CKD), intricately linked to adverse prognoses, heightened cardiovascular risks, and increased mortality rates. Extensive studies have found a close and complex association between gut microbiota, kidney and muscle. On one front, patients with CKD manifest disturbances in gut microbiota and alterations in serum metabolites. These abnormal microbiota composition and metabolites in turn participate in the development of CKD. On another front, altered gut microbiota and its metabolites may lead to significant changes in metabolic homeostasis and inflammation, ultimately contributing to the onset of sarcopenia. The disturbance of gut microbial homeostasis, coupled with the accumulation of toxic metabolites, exerts deleterious effects on skeletal muscles in CKD patients with sarcopenia. This review meticulously describes the alterations observed in gut microbiota and its serum metabolites in CKD and sarcopenia patients, providing a comprehensive overview of pertinent studies. By delving into the intricate interplay of gut microbiota and serum metabolites in CKD-associated sarcopenia, we aim to unveil novel treatment strategies for ameliorating their symptoms and prognosis.

Prediction of hematologic toxicity in luminal type breast cancer patients receiving neoadjuvant chemotherapy using CT L1 level skeletal muscle index

This study aims to explore the correlation between the CT-L1 and L3 body composition parameters and analyze the relationship between L1 body composition and hematologic toxicity in luminal-type breast cancer patients undergoing neoadjuvant chemotherapy. Data from 140 luminal-type breast cancer patients who underwent surgical treatment after neoadjuvant chemotherapy were analyzed retrospectively. Spearman analysis was used to assess the correlation between CT-L1 and CT-L3 body composition parameters pre-neoadjuvant chemotherapy. Additionally, univariate and multivariate logistic regression analyses were performed to identify factors influencing hematologic toxicity. CT-L1 body composition parameters were positively correlated with CT-L3 body composition parameters in 34 patients. Severe hematological toxicity occurred in 46 cases among the patient cohort. A skeletal muscle index (SMI) of < 32.91 cm2/m2, initial tumor size ≥ 3.335 cm, and a glucose-to-neutrophil ratio (GLR) ≥ 2.88 were identified as independent risk factors for severe hematologic toxicity during neoadjuvant chemotherapy in luminal-type breast cancer patients. The sample size in this study is small, and the predictive capacity of GLR in hematologic toxicity requires further research for comprehensive validation. CT-L1 analysis represents a viable alternative to CT-L3 analysis for body composition assessment. Patients with a low skeletal muscle index were more prone to experiencing severe hematologic toxicity during neoadjuvant chemotherapy.