Low skeletal muscle mass is associated with mortality in kidney transplant recipients

The Prognostic Significance of Preoperative Computed Tomography Diagnosed Sarcopenia on Allograft and Postoperative Outcomes Following Kidney Transplantation: A Systematic Review and Meta-Analysis

BACKGROUND

The identification of individuals who will benefit most from kidney transplantation is challenging, with no clear consensus as to which clinical features provide the most prognostic information. Recently, computed tomography (CT)-diagnosed sarcopenia has proven to be accurate in predicting poorer outcomes solid organ transplant recipients. This systematic review and meta-analysis evaluates the role of sarcopenia, as defined by preoperative CT, in the prediction of postoperative recipient and allograft outcomes in patients undergoing kidney transplantation.

METHODS

A comprehensive literature search was performed on Medline, Embase, Google Scholar and CINAHL databases. Seven articles involving 1153 patients were included in this review.

RESULTS

There was strong evidence to suggest that CT-defined sarcopenia was associated with increased mortality (OR: 2.72, 95% CI, 1.66-4.47, P < .0001) and greater likelihood of readmission (OR: 1.98, 95% CI, 1.34-2.92, P = .00006). There was a lack of evidence to support the use of preoperative CT to define sarcopenia as a prognostic factor for allograft and other postoperative outcomes following kidney transplantation.

CONCLUSIONS

This systematic review and meta-analysis demonstrates evidence to suggest pretransplant sarcopenia identified on CT imaging is predictive of increased mortality and readmission. Given the limitations of evidence related to risk of bias and heterogeneity, there is a need for more robust prospective research to elucidate the true effect of CT diagnosed sarcopenia as a prognostic factor in the kidney transplant setting.

Performance of Five Estimated Glomerular Filtration Rate Equations in Vietnamese Kidney Transplant Recipients: A Cross-Sectional Study

BACKGROUND

Despite the critical role of glomerular filtration rate (GFR) assessment in monitoring kidney transplants, the most accurate estimate remains uncertain. This study aimed to evaluate the performance of established estimated GFR (eGFR) equations in the Vietnamese population.

METHODS

This cross-sectional study involving 299 Vietnamese kidney transplant recipients (KTRs) compared measured GFR (mGFR), determined using technetium-99m-diethylenetriaminepentaacetate (99mTc-DTPA) renal dynamic scintigraphy, with five eGFR equations (Modification of Diet in Renal Disease [MDRD], Asian modified Chronic Kidney Disease Epidemiology Collaboration [CKD-EPI], CKD-EPI SCysC 2012, CKD-EPI SCr 2021, and CKD-EPI SCr-SCysC 2021). The performances of the five eGFR equations were compared based on bias, P30 accuracy, absolute accuracy, precision, root mean square error (RMSE), concordance correlation coefficient (CCC), and Pearson's correlation coefficient (r), along with their 95% confidence intervals (CIs).

RESULTS

CKD-EPI SCr-SCysC 2021 showed the best performance. The values for median bias, P30 accuracy, absolute accuracy, precision, RMSE, CCC, and r were: 2.57 [1.22; 3.55] mL/min/1.73 m2, 87.6% [83.3; 90.6], 10.0% [8.3; 11.7], 11.29 [9.57; 13.40] mL/min/1.73 m2, 11.54 [10.42; 12.92], 0.787 [0.737; 0.828], and 0.810 [0.759; 0.850], respectively. The MDRD equation did not show significantly lower precision and accuracy than the CKD-EPI SCr-SCysC 2021 equation. All five equations demonstrated improved accuracy in the mGFR ≥ 60 mL/min/1.73 m2 subgroup compared to the mGFR < 60 mL/min/1.73 m2 subgroup.

CONCLUSIONS

CKD-EPI SCr-SCysC 2021 is the most accurate eGFR equation for Vietnamese KTRs. Further studies with larger cohorts and comparisons with gold-standard methods are needed to confirm these findings.

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.

Assessing Patients beyond the Simple Optics of BMI: The Concomitant Role of Sarcopenia and BMI in Predicting Kidney Transplant Outcomes

BACKGROUND

Body composition is associated with prognosis in many clinical settings, and patients undergoing kidney transplantation are often high risk with multiple comorbidities. We aimed to assess the effect of sarcopenia and body composition on transplant outcomes.

METHODS

We performed a retrospective analysis of 274 kidney transplants with CT scans within 3 years of transplantation. The skeletal muscle index (SMI) at the L3 vertebrae was used to evaluate sarcopenia (SMI < 40.31 cm2/m2 in males, <30.88 cm2/m2 in females). Sarcopenia, body mass index (BMI), and the visceral-to-subcutaneous-fat ratio (VSR) were assessed separately. We also used a composite BMI/sarcopenia measurement in four patient groups: BMI < 25/Non-Sarcopenic, BMI < 25/Sarcopenic, BMI > 25/Non-Sarcopenic, and BMI > 25/Sarcopenic. The outcomes measured were eGFR (1 and 3 months; and 1, 3, and 5 years), delayed graft function (DGF), rejection, major adverse cardiovascular events (MACE), and post-operative complications.

RESULTS

Sarcopenia was associated with an increased 1-year risk of MACE (OR 3.41, p = 0.036). BMI alone had no effect on function, DGF, MACE, or on other complications. High VSR was associated with a lower risk of DGF (OR 0.473, p = 0.016). When sarcopenia and BMI were assessed together, the BMI > 25/sarcopenic patients had the poorest outcomes, with increased risk of MACE (OR 26.06, p = 0.001); poorer eGFR at 1, 3, 12, and 36 months; (p < 0.05 at all timepoints), and poorer graft survival (p = 0.002).

CONCLUSIONS

Sarcopenia alone is associated with an increased risk of MACE. Overweight sarcopenic patients are additionally at increased risk of graft loss and have poorer graft function for up to three years.

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.

Lean body mass in living kidney donors impacts postoperative renal function

PURPOSE

A living donor kidney transplant is the optimal treatment for chronic renal impairment. Our objective is to assess if lean skeletal muscle mass and donor factors such as body mass index, hypertension, and age impact on renal function following donor nephrectomy.

METHODS

Potential donors undergo CT angiography as part of their work-up in our institution. Using dedicated software (Horos®), standardized skeletal muscle area measured at the L3 vertebrae was calculated. When corrected for height, skeletal muscle index can be derived. Skeletal muscle mass index below predefined levels was classified as sarcopenic. The correlation of CT-derived skeletal muscle index and postoperative renal function at 12 months was assessed. Co-variables including donor gender, age, body mass index (BMI), and presence of pre-op hypertension were also assessed for their impact on postoperative renal function.

RESULTS

275 patients who underwent living donor nephrectomy over 10 years were included. Baseline pre-donation glomerular filtration rate (GFR) and renal function at one year post-op were similar between genders. 29% (n = 82) of patients met the criteria for CT-derived sarcopenia. Sarcopenic patients were more likely to have a higher GFR at one year post-op (69.3 vs 63.9 mL/min/1.73 m2, p < 0.001). The main factors impacting better renal function at one year were the presence of sarcopenia and younger age at donation.

CONCLUSION

When selecting donors, this study highlights that patients with low skeletal mass are unlikely to underperform in terms of recovery of their renal function postoperatively at one year when compared to patients with normal muscle mass and should not be a barrier to kidney donation.

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.

Association between pulse pressure and low muscle mass in Korean adults: A nationwide cross-sectional study

Sarcopenia is characterized by a loss of muscle mass and strength and is associated with a high risk of cardiovascular events and increased mortality. Pulse pressure (PP) serves as a marker for changes in heart structure and function, as well as arterial stiffness. A high PP also increases the risk of cardiovascular disease and all-cause mortality. However, the relationship between PP and sarcopenia is poorly understood. We used the data of participants of the Korea National Health and Nutrition Examination Survey (KNHANES) of 2008 to 2011. Participants were divided into a control group (PP < 40 mm Hg) and a high-PP group (PP ≥ 40 mm Hg). PP was calculated by subtracting the diastolic blood pressure (DBP) from the systolic blood pressure (SBP), and the low muscle index was assessed using appendicular skeletal muscle mass (ASM) normalized by body mass index (BMI). Multiple logistic regression analyses were performed to examine the association between PP and the prevalence of low muscle mass, adjusting for potential confounders. The high-PP group had a higher age, SBP, DBP, and prevalence of hypertension, diabetes and hyperlipidemia than the control group. The high-PP group had a higher prevalence of low muscle mass than the control group in all models. A high PP is significantly associated with a higher prevalence of low muscle mass. Therefore, PP monitoring may help identify individuals at risk of sarcopenia and guide interventions to improve health outcomes.