Skeletal Muscle Index as a Prognostic Marker for Kidney Transplantation in Older Patients

Myosteatosis is associated with poor survival after kidney transplantation: a large retrospective cohort validation

PURPOSE

We aim to establish diagnostic thresholds of sarcopenia and myosteatosis based on CT measurements, and to validate their prognostic value in a large cohort of kidney transplant recipients.

METHODS

Local healthy population with abdominal CT between 2010 and 2022, and patients underwent kidney transplantation between 2015 and 2019 at our center were retrospectively included. The skeletal muscle index and muscle attenuation of abdominal muscles were calculated based on CT image at the middle of the third lumbar vertebra. Primary endpoints included all-cause mortality and death censored allograft survival.

RESULTS

Age- and sex-specific thresholds for sarcopenia and myosteatosis were established based on 1598 healthy local population. The final patient cohort consisted of 992 kidney transplant recipients (median age 34 years, interquartile range 28-44 years; 694 males), including 33 (3.3%) with sarcopenia and 95 (9.5%) with myosteatosis. Multivariate analysis revealed myosteatosis (adjusted hazard ratio = 3.08, p = 0.022) was an independent baseline risk factor of mortality after adjusting for age, the history of cancer, and the history of cardiovascular event. Multivariate analysis found preemptive transplantation (adjusted hazard ratio = 0.36, p = 0.037) was an independent protective factor of allograft loss. No difference was found in the prognosis between kidney transplant recipients with and without sarcopenia.

CONCLUSION

Myosteatosis was an independent risk factor of mortality after kidney transplantation, but sarcopenia was not. Neither sarcopenia nor myosteatosis was associated with graft loss.

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.

Sarcopenic obesity is associated with adverse outcomes after kidney transplantation: a retrospective cohort study

PURPOSE

Sarcopenia was found to be a poor prognostic factor in kidney transplant recipients, but the role of sarcopenia obesity remains unclear. This study aimed to explore the effect of sarcopenic obesity on kidney transplantation.

METHODS

A retrospective analysis was performed on kidney transplant recipients between 2015 and 2019. Pretransplant CT scans were utilized to assess sarcopenia and visceral obesity. Based on the presence or absence of sarcopenia and visceral obesity, the recipients were classified into four distinct groups.

RESULTS

The recipients were categorized into four groups based on their characteristics: the nonsarcopenic nonobesity group (n = 493, 49.85%), the nonsarcopenic obesity group (n = 248, 25.08%), the sarcopenic nonobesity group (n = 188, 19.01%), and the sarcopenic obesity group (n = 60, 6.07%). Multivariate analysis, identified sarcopenic obesity was as an independent risk factor for mortality following kidney transplantation (adjusted hazard ratio, 5.861; 95% confidence interval [CI]: 1.627-21.108; P = 0.007). Additionally, sarcopenic obesity was associated with an increased risk of delayed graft function (adjusted odds ratio [aOR], 3.342; 95% CI 1.421-7.745; P = 0.005), perioperative incision infection (aOR, 9.654; 95% CI 1.572-60.648; P = 0.011), perioperative pulmonary infection (aOR, 2.557; 95% CI 1.208-5.215; P = 0.011), and readmission within 3 months (aOR, 2.100; 95% CI 1.051-4.017; P = 0.029). While sarcopenic obesity was found to be associated with impaired graft renal function, it did not show a significant correlation with death-censored graft survival or quality of life.

CONCLUSION

The presence of sarcopenic obesity prior to kidney transplantation represents an independent risk factor for mortality, and it is also linked to a range of unfavorable outcomes.

Nutrition support management of organ transplant recipients in the acute posttransplant phase

Patients who undergo solid organ transplant can have an extensive and challenging postoperative course. The chronicity of the disease state prior to transplant in combination with transplant-specific complications and immunosuppressant medications can lead to distinct challenges that are not observed in other critically ill patients. Although the manifestation of posttransplant complications may be specific to the organ being transplanted, there are common transplant challenges that affect nutrition therapy in these patients. Effects of malnutrition, metabolic aberrations, and posttransplant organ dysfunction should be considered when developing a nutrition care plan for patients in the immediate posttransplant phase. This article addresses the various complications that can arise in the immediate posttransplant phase among patients undergoing solid organ transplant and the appropriate nutrition interventions or considerations for this specialized patient population.

Creatinine-cystatin C ratio and death with a functioning graft in kidney transplant recipients

Death with a functioning graft is important cause of graft loss after kidney transplantation. However, little is known about factors predicting death with a functioning graft among kidney transplant recipients. In this study, we evaluated the association between post-transplant creatinine-cystatin C ratio and death with a functioning graft in 1592 kidney transplant recipients. We divided the patients into tertiles based on sex-specific creatinine-cystatin C ratio. Among the 1592 recipients, 39.5% were female, and 86.1% underwent living-donor kidney transplantation. The cut-off value for the lowest creatinine-cystatin C ratio tertile was 0.86 in males and 0.73 in females. The lowest tertile had a significantly lower 5-year patient survival rate and was independently associated with death with a functioning graft (adjusted hazard ratio 2.574, 95% confidence interval 1.339-4.950, P < 0.001). Infection was the most common cause of death in the lowest tertile group, accounting for 62% of deaths. A low creatinine-cystatin C ratio was significantly associated with an increased risk of death with a functioning graft after kidney transplantation.

Diagnosis, prevalence, and outcomes of sarcopenia in kidney transplantation recipients: A systematic review and meta-analysis

The prevalence of sarcopenia and its clinical predictors and clinical impact vary among kidney transplant recipients (KTRs), in part because of different diagnostic criteria. This study aimed to assess the reported diagnosis criteria of sarcopenia and compare them in terms of prevalence, clinical predictors, and impact of sarcopenia. The Medline, Embase, and Cochrane Library were searched for the full-length reports published until 28 January 2022. The subgroup analysis, meta-regression, and sensitivity analysis were performed and heterogeneity was assessed using the I² . A total of 681 studies were retrieved, among which only 23 studies (including 2535 subjects, 59.7% men, mean age 49.8 years) were eventually included in the final analysis. The pooled prevalence in these included studies was 26% [95% confidence interval (95% CI): 20-34%, I²  = 93.45%], including 22% (95% CI: 14-32%, I²  = 88.76%) in men and 27% (95% CI: 14-41%, I²  = 90.56%) in women (P = 0.554 between subgroups). The prevalence of sarcopenia diagnosed using low muscle mass was 34% (95% CI: 21-48%, I²  = 95.28%), and the prevalence of using low muscle mass in combination with low muscle strength and/or low physical performance was 21% (95% CI: 15-28%, I²  = 90.37%) (P = 0.08 between subgroups). In meta-regression analyses, the mean age (regression coefficient: 1.001, 95% CI: 0.991-1.011) and percentage male (regression coefficient: 0.846, 95% CI: 0.367-1.950) could not predict the effect size. Lower body mass index (odds ratio (OR): 0.57, 95% CI: 0.39-0.84, I²  = 61.5%), female sex (OR: 0.31, 95% CI: 0.16-0.61, I²  = 0.0%), and higher age (OR: 1.08, 95% CI: 1.05-1.10, I²  = 10.1%) were significantly associated with a higher risk for sarcopenia in KTRs, but phase angle (OR: 0.81, 95% CI: 0.16-4.26, I²  = 84.5%) was not associated with sarcopenia in KTRs. Sarcopenia was not associated with rejections (risk ratio (RR): 0.67, 95% CI: 0.23-1.92, I²  = 12.1%), infections (RR: 1.03, 95% CI: 0.34-3.12, I²  = 87.4%), delayed graft functions (RR: 0.81, 95% CI: 0.46-1.43, I²  = 0.0%), and death (RR: 0.95, 95% CI: 0.32-2.82, I²  = 0.0%) in KRTs. Sarcopenia was found to be very common in KRTs. However, we have not found that sarcopenia had a negative impact on clinical health after kidney transplantation. Large study cohorts and multicentre longitudinal studies in the future are urgently needed to explore the prevalence and prognosis of sarcopenia in kidney transplant patients.

Study of Post-Kidney Transplantation Parietal Complications and Presarcopenia

BACKGROUND

Sarcopenia is defined as a loss of muscle mass and strength. Its effects on postoperative outcomes in oncology and geriatrics have already been shown. Approximately 40% of patients in end-stage renal failure are affected with sarcopenia. A recent study suggests that sarcopenia could predict surgical complications after renal transplantation in obese patients. The aim of this study was to evaluate the effect of sarcopenia on parietal complications (eg, wound healing, lymphocele, hematoma).

METHODS

Two indices of muscle fat infiltration (intra-muscular adipose content [IMAC], Hounsfield unit average calculation [HUAC]) and 3 of muscle mass index (total psoas index [TPI], visceral fat area/total abdominal muscle area [VFA/TAMA], and skeletal muscle mass index [SMMI]) were retrospectively measured on pretransplant computed tomography scans for patients undergoing kidney transplantation between 2007 and 2017. Patients were considered sarcopenic when the index was above the third quartile for muscle fat infiltration (IMAC, HUAC) and VFA/TAMA, and under the first quartile for muscle mass (TPI, SMMI). The occurrence of wound healing, collection (hematoma and lymphocele), and acute rejection were compared between sarcopenic and nonsarcopenic patients.

RESULTS

Of 484 transplanted patients, 117 patients had a computed tomography scan before transplantation. Patients with a high HUAC had significantly more collections (P = .02) and total parietal complications (P = .09). Patients with a high IMAC had significantly more acute rejection (P = .001).

CONCLUSIONS

Muscle fat infiltration appears to influence the outcome of renal transplantation. The management of sarcopenia in pretransplantation should be a subject of further research.

Muscle mass, muscle strength and mortality in kidney transplant recipients: results of the TransplantLines Biobank and Cohort Study

BACKGROUND

Survival of kidney transplant recipients (KTR) is low compared with the general population. Low muscle mass and muscle strength may contribute to lower survival, but practical measures of muscle status suitable for routine care have not been evaluated for their association with long-term survival and their relation with each other in a large cohort of KTR.

METHODS

Data of outpatient KTR ≥ 1 year post-transplantation, included in the TransplantLines Biobank and Cohort Study (ClinicalTrials.gov Identifier: NCT03272841), were used. Muscle mass was determined as appendicular skeletal muscle mass indexed for height² (ASMI) through bio-electrical impedance analysis (BIA), and by 24-h urinary creatinine excretion rate indexed for height² (CERI). Muscle strength was determined by hand grip strength indexed for height² (HGSI). Secondary analyses were performed using parameters not indexed for height². Cox proportional hazards models were used to investigate the associations between muscle mass and muscle strength and all-cause mortality, both in univariable and multivariable models with adjustment for potential confounders, including age, sex, body mass index (BMI), estimated glomerular filtration rate (eGFR) and proteinuria.

RESULTS

We included 741 KTR (62% male, age 55 ± 13 years, BMI 27.3 ± 4.6 kg/m²), of which 62 (8%) died during a median [interquartile range] follow-up of 3.0 [2.3-5.7] years. Compared with patients who survived, patients who died had similar ASMI (7.0 ± 1.0 vs. 7.0 ± 1.0 kg/m²; P = 0.57), lower CERI (4.2 ± 1.1 vs. 3.5 ± 0.9 mmol/24 h/m²; P < 0.001) and lower HGSI (12.6 ± 3.3 vs. 10.4 ± 2.8 kg/m²; P < 0.001). We observed no association between ASMI and all-cause mortality (HR 0.93 per SD increase; 95% confidence interval [CI] [0.72, 1.19]; P = 0.54), whereas CERI and HGSI were significantly associated with mortality, independent of potential confounders (HR 0.57 per SD increase; 95% CI [0.44, 0.81]; P = 0.002 and HR 0.47 per SD increase; 95% CI [0.33, 0.68]; P < 0.001, respectively), and associations of CERI and HGSI with mortality remained independent of each other (HR 0.68 per SD increase; 95% CI [0.47, 0.98]; P = 0.04 and HR 0.53 per SD increase; 95% CI [0.36, 0.76]; P = 0.001, respectively). Similar associations were found for unindexed parameters.

CONCLUSIONS

Higher muscle mass assessed by creatinine excretion rate and higher muscle strength assessed by hand grip strength are complementary in their association with lower risk of all-cause mortality in KTR. Muscle mass assessed by BIA is not associated with mortality. Routine assessment using both 24-h urine samples and hand grip strength is recommended, to potentially target interdisciplinary interventions for KTR at risk for poor survival to improve muscle status.

Low muscle mass and early hospital readmission post-kidney transplantation

PURPOSE

Patients exhibiting features of frailty and sarcopenia increasingly are presenting for kidney transplantation (KT) assessment. Sarcopenia, when ascertained by radiological measures, is associated with a higher transplant waiting list mortality; but studies on post-operative outcomes are lacking. We aimed to determine the clinical significance of low muscle mass in chronic kidney disease (CKD) patients subsequently receiving KT.

METHODS

We retrospectively analyzed 63 patients with Stage 4-5 CKD who, between 2012 and 2020, had undergone abdominal computed tomography (CT) scanning up to 2 years before KT. The degree of skeletal muscle loss was assessed using the total cross-sectional skeletal muscle area at the third lumbar vertebral level (L3). Cox proportional-hazards regression and Frailty models were used to identify risk factors for early hospital readmission post KT.

RESULTS

Thirty-four patients (54%) displayed low muscle mass, which was independently associated with a lower serum creatinine and phosphate, lower body mass index, lower mean muscle attenuation of the L3 cross-sectional area, and higher serum parathyroid hormone (for all p < 0.05). Deceased donor transplant recipients (n = 45) with low muscle mass demonstrated greater hospital readmissions within 30 days of KT [adjusted hazard ratio (HR) = 4.24, 95% CI 1.40-12.90, p = 0.01].

CONCLUSION

Low muscle mass is highly prevalent in the pre-transplant CKD population and is associated with increased hospital readmission in the early post-transplant period.

Sarcopenia and Frailty: Challenges in Mainstream Nephrology Practice

Sarcopenia and frailty are prevalent in the chronic kidney disease (CKD) population. Sarcopenia is characterised by the loss of muscle mass and function, while frailty is defined as a multi-system impairment associated with increased vulnerability to stressors. There is substantial overlap between the 2 conditions, particularly with regards to physical aspects: low grip strength, gait speed and low muscle mass. Both sarcopenia and frailty have been associated with a wide range of adverse health outcomes. Although there is no recommended pharmacological treatment as yet, it is widely accepted that exercise training and nutritional supplementation are the key interventions to maintain skeletal muscle mass and strength. This review aims to present a comprehensive overview of sarcopenia and frailty in patients with CKD.