Presence of Sarcopenia before Kidney Transplantation Is Associated with Poor Outcomes

Age Is Just a Number for Older Kidney Transplant Patients

The rise in the mean age of the global population has led to an increase in older kidney transplant (KT) patients. This demographic shift, coupled with the ongoing organ shortage, requires a nuanced understanding of which older adults are most suitable for KT. Recognizing the increased heterogeneity among older adults and the limitations of solely relying on chronological age, there is a need to explore alternative aging metrics beyond chronological age. In this review, we discuss the impact of older age on access to KT and postoperative outcomes. Emphasizing the need for a comprehensive evaluation that extends beyond chronological age, we explore alternative aging metrics such as frailty, sarcopenia, and cognitive function, underscoring their potential role in enhancing the KT evaluation process. Most importantly, we aim to contribute to the ongoing discourse, fostering an optimized approach to KT for the rapidly growing population of older adults.

Dialysis Duration, Time Interaction, and Visceral Fat Accumulation: A 6-Year Posttransplantation Study

BACKGROUND

Kidney transplantation (KT) leads to body composition change, particularly increasing the fat mass. However, limited researches have focused on the long-term follow-up of these changes and factors influencing body composition after KT.

METHODS

This study evaluated body composition in 31 adult KT recipients, measuring body mass index (BMI), the psoas muscle mass index (PMI) representing muscle mass, visceral and subcutaneous adipose tissue (VAT and SAT) representing fat mass, and skeletal muscle radiodensity (SMR) representing muscle quality before KT and at 2, 4, and 6 years posttransplantation using computed tomography. Linear mixed models (LMM) analyzed temporal changes and contributing factors, while growth curve models assessed influence of these factors on body composition changes posttransplantation.

RESULTS

Following KT, BMI, and PMI remained stable, while SAT increased significantly, revealing a 1.30-fold increase from baseline 2 years after transplantation. Similarly, a substantial increase in VAT was observed, with a 1.47-fold increase from baseline 2 years after transplantation with a further 1.75-fold increase 6 years after transplantation. In contrast, SMR decreased with a 0.86-fold decrease from baseline after 2 years. VAT increase was significantly influenced by the interaction between posttransplantation and dialysis duration. Growth curve models confirmed this interaction effect persistently influenced VAT increase posttransplantation.

CONCLUSIONS

The study revealed that KT promoted significant alterations in body composition characterized by increase in the VAT and SAT and a decline in SMR. Notably, dialysis duration and its interaction with posttransplantation duration emerged as significant factors influencing VAT increase.

Abdominal computed tomography measurements of body composition and waitlist mortality in kidney transplant candidates

Body mass index is often used to determine kidney transplant (KT) candidacy. However, this measure of body composition (BC) has several limitations, including the inability to accurately capture dry weight. Objective computed tomography (CT)-based measures may improve pre-KT risk stratification and capture physiological aging more accurately. We quantified the association between CT-based BC measurements and waitlist mortality in a retrospective study of 828 KT candidates (2010-2022) with clinically obtained CT scans using adjusted competing risk regression. In total, 42.5% of candidates had myopenia, 11.4% had myopenic obesity (MO), 68.8% had myosteatosis, 24.8% had sarcopenia (probable = 11.2%, confirmed = 10.5%, and severe = 3.1%), and 8.6% had sarcopenic obesity. Myopenia, MO, and sarcopenic obesity were not associated with mortality. Patients with myosteatosis (adjusted subhazard ratio [aSHR] = 1.62, 95% confidence interval [CI]: 1.07-2.45; after confounder adjustment) or sarcopenia (probable: aSHR = 1.78, 95% CI: 1.10-2.88; confirmed: aSHR = 1.68, 95% CI: 1.01-2.82; and severe: aSHR = 2.51, 95% CI: 1.12-5.66; after full adjustment) were at increased risk of mortality. When stratified by age, MO (aSHR = 2.21, 95% CI: 1.28-3.83; P interaction = .005) and myosteatosis (aSHR = 1.95, 95% CI: 1.18-3.21; P interaction = .038) were associated with elevated risk only among candidates <65 years. MO was only associated with waitlist mortality among frail candidates (adjusted hazard ratio = 2.54, 95% CI: 1.28-5.05; P interaction = .021). Transplant centers should consider using BC metrics in addition to body mass index when a CT scan is available to improve pre-KT risk stratification at KT evaluation.

Assessing nutrition status, sarcopenia, and frailty in adult transplant recipients

The assessment of nutrition status, sarcopenia, and frailty holds significant relevance in the context of adult transplantation, as these factors are associated with an unfavorable prognosis; thus, transplant candidates must undergo a full nutrition assessment. Screening tools may be used to prioritize patients, this can be done using the Nutrition Risk Screening 2002 or Royal Free Hospital-Nutritional Prioritizing Tool. Subsequently, a thorough nutrition-focused physical examination should be conducted to evaluate clinical signs of nutrition deficiencies, fat and muscle loss, and fluid overload; dietary history and current intake must also be assessed. Apart from physical examination, specific testing for sarcopenia and frailty are recommended. For sarcopenia assessment, specifically for muscle quantification, the gold standard is the cross-sectional measurement of the muscle at L3 obtained from a computed tomography scan or magnetic resonance imaging; dual-energy x-ray absorptiometry is also a good tool especially when appendicular skeletal muscle index is calculated. Other more readily available options include phase angle from bioelectrical impedance or bioimpedance spectroscopy. In the sarcopenia assessment, muscle function evaluation is required, handgrip strength stands as the primary test for this purpose; this test is also part of the subjective global assessment and is included in some frailty scores. Finally, for frailty assessment, the Short Physical Performance Battery is useful for evaluating physical frailty, and for a multidimensional evaluation, the Fried frailty phenotype can be used. Specifically for liver transplant candidates, the use of Liver Frailty Index is recommended.

Validity of computed tomography defined body composition as a prognostic factor for functional outcome after kidney transplantation

BACKGROUND

The prevalence of sarcopenia is markedly higher in kidney transplant candidates than in the general population. It is a syndrome characterized by progressive and generalized loss of skeletal muscle mass and strength, which increases the risk of adverse postoperative outcomes.

METHODS

We studied the impact of computed tomography defined preoperative sarcopenia, defined as a skeletal muscle index below age and gender specific cut-off values, on postoperative physical functional outcomes (grip strength, 4-m walking test, timed up and go, and sit to stand) at 6 months follow up.

RESULTS

A total of 107 patients transplanted between 2015 and 2019 were included in this single-centre study. Mean age was 60.3 (±13.1), and 68.2% of patients were male. Ten patients (9.4%) were identified as sarcopenic. Sarcopenic patients were younger (55.6 (±15.1) vs. 60.8 (±12.9) years), more likely to be female (60.0% vs. 28.9%), and had an increased dialysis vintage (19 [2.5-32.8] vs. 9 [0.0-21.0] months) in comparison with their non-sarcopenic counterparts. In univariate analysis, they had a significantly lower body mass index and skeletal muscle area (P ≤ 0.001). In multivariate regression analysis, skeletal muscle index was significantly associated with grip strength (β = 0.690, R2  = 0.232) and timed up and go performance (β = -0.070, R2  = 0.154).

CONCLUSIONS

We identified a significant association between sarcopenia existing pre-transplantation and poorer 6 months post-transplantation physical functioning with respect to hand grip strength and timed up and go tests in kidney transplant recipients. These results could be used to preoperatively identify patients with an increased risk of poor postoperative physical functional outcome, allowing for preoperative interventions to mitigate these risks.

Coexistence of Low Muscle Mass and Osteoporosis as a Predictor of Fragility Fractures in Long-Term Kidney Transplant Recipients

INTRODUCTION

Sarcopenia and osteoporosis are highly prevalent among kidney transplant recipients (KTRs). Although osteoporosis is known to increase fracture risk in KTRs, it is unclear whether sarcopenia or osteosarcopenia is associated with this increased risk. Thus, we aimed to investigate the association of the coexistence of low muscle mass (LMM) and osteoporosis with the risk of fracture in long-term KTRs.

METHODS

Exactly 342 stable KTRs underwent dual-energy X-ray absorptiometry and skeletal muscle mass index (SMI) measurement using bioelectrical impedance analysis.

RESULTS

LMM and osteoporosis were observed in 109 (31.9%) and 93 patients (27.2%), respectively. During a follow-up period of 5.1 years, 48 (14.0%) fractures occurred. KTRs with LMM had a higher fracture risk, but this was not significant (adjusted hazard ratio [aHR] 1.82, 95% confidence interval [CI] 0.94-3.50, p = 0.073). Similar results were obtained in KTRs with osteoporosis (aHR 1.84, 95% CI 0.96-3.47, p = 0.063). We divided the KTRs into four groups according to the presence of LMM and/or osteoporosis. The cumulative incidence rates of fractures were 13.0%, 11.1%, 10.5%, and 31.3% in the KTRs without both LMM and osteoporosis, those with LMM alone, those with osteoporosis alone, and those with both, respectively. The KTRs with both LMM and osteoporosis had a 2.92fold higher risk of fractures (95% CI 1.29-6.49; p = 0.010) than those without both LMM and osteoporosis.

CONCLUSION

Long-term KTRs with the coexistence of LMM and osteoporosis had an independently higher risk of fragility fractures than those without both LMM and osteoporosis. The combination of SMI and osteoporosis definitions can be used to identify KTRs with a high fracture risk.

Impact of Sarcopenia on Percutaneous Epidural Balloon Neuroplasty in Patients with Lumbar Spinal Stenosis: A Retrospective Analysis

Background and Objectives: With the aging population, the incidence of degenerative lumbar spinal stenosis (LSS) is increasing. Sarcopenia is an age-related muscular decrease. Although epidural balloon neuroplasty is effective in patients with LSS refractory to conventional treatments, its effect has not been assessed in patients with sarcopenia. Therefore, this study evaluated the effect of epidural balloon neuroplasty in patients with LSS and sarcopenia. Materials and Methods: This retrospective study reviewed the following details from the electronic medical records: patient characteristics, including sex, age, body mass index, diabetes, hypertension, stenosis grading, pain duration, location, pain intensity, and medications. Back and leg pain intensity was evaluated before and after the procedure at one, three, and six months during the follow-up period. A generalized estimating equations model was used at six months follow-up. Patients were divided into sarcopenia and non-sarcopenia groups using the cross-sectional area of the psoas muscle at the level of L3 on magnetic resonance imaging. Results: A total of 477 patients were included (sarcopenia group: 314 patients, 65.8%; non-sarcopenia group: 163 patients, 34.2%). Age, sex, body mass index, and medication quantification scale III were statistically different between both groups. The generalized estimating equations analyses-with unadjusted and adjusted estimation-revealed a significantly reduced pain intensity after the procedure compared to the baseline in both groups. The difference in pain intensity between both groups was not statistically different. Conclusions: Percutaneous epidural balloon neuroplasty may be considered for patients with chronic lumbar LSS regardless of accompanying sarcopenia.

Sarcopenia of kidney transplant recipients as a predictive marker for reduced graft function and graft survival after kidney transplantation

PURPOSE

The association between sarcopenia of kidney transplant recipients and outcome after kidney transplantation (KT) has not yet been fully understood and is still considered controversial. The aim of our study was to analyze the impact of pre-transplant sarcopenia on graft function, postoperative complication rates, and survival of the patients after renal transplantation.

METHODS

In this retrospective single-center study, all patients who underwent KT (01/2013-12/2017) were included. Demographic data, rejection rates, delayed graft function, and graft and patient survival rates were analyzed. Sarcopenia was measured in computed tomography images by the sex-adjusted Hounsfield unit average calculation (HUAC).

RESULTS

During the study period, 111 single KTs (38 women and 73 men) were performed. Living donor kidney transplants were performed in 48.6%. In total, 32.4% patients had sarcopenia. Sarcopenic patients were significantly older (59.6 years vs. 49.8 years; p < 0.001), had a higher body mass index (BMI = 27.6 kg/m2 vs. 25.0 kg/m2; p = 0.002), and were more likely to receive deceased donor kidneys (72.2% vs. 41.3%; p = 0.002). Interestingly, 3 years after KT, the creatinine serum levels were significantly higher (2.0 mg/dl vs. 1.5 mg/dl; p = 0.001), whereas eGFR (39.9 ml/min vs. 53.4 ml/min; p = 0.001) and graft survival were significantly lower (p = 0.004) in sarcopenic transplant recipients. Sarcopenic patients stayed in hospital significantly longer postoperatively than those who were non-sarcopenic.

CONCLUSIONS

At the time of kidney transplantation, sarcopenia was found to predict reduced long-term graft function and diminished graft survival after KT. The early identification of sarcopenic patients can not only enable an optimized selection of recipients, but also the initiation of pre-habilitation programs during the waiting period.

The "adult inactivity triad" in patients with chronic kidney disease: A review

Background

The "pediatric inactivity triad" framework consists of three complex, interrelated conditions influencing physical inactivity and associated health risks. Evidence on the beneficial effects of physical activity in adults with chronic kidney disease (CKD) continues to grow, but few studies have explored the complex interactions behind inactivity in this population.

Results

Based on the "pediatric inactivity triad" framework and prior research, we would like to propose a new concept, the "adult inactivity triad" in CKD, including (1) exercise deficit disorder, (2) sarcopenia, and (3) physical illiteracy. Individuals can shift from "adult inactivity triad" to "adult activity triad" and move at different rates and directions along the arrows in each of the three components.

Conclusion

This review explores and summarizes previous research on the three main adult inactivity triad components in the chronic kidney disease population.