Sarcopenia and mortality after liver transplantation

Analytic morphomics, core muscle size, and surgical outcomes

OBJECTIVE

Assess the relationship between lean core muscle size, measured on preoperative cross-sectional images, and surgical outcomes.

BACKGROUND

Novel measures of preoperative risk are needed. Analytic morphomic analysis of cross-sectional diagnostic images may elucidate vast amounts of patient-specific data, which are never assessed by clinicians.

METHODS

The study population included all patients within the Michigan Surgical Quality Collaborative database with a computerized tomography(CT) scan before major, elective general or vascular surgery (N = 1453). The lean core muscle size was calculated using analytic morphomic techniques. The primary outcome measure was survival, whereas secondary outcomes included surgical complications and costs. Covariate adjusted outcomes were assessed using Kaplan-Meier analysis, multivariate cox regression, multivariate logistic regression, and generalized estimating equation methods.

RESULTS

The mean follow-up was 2.3 years and 214 patients died during the observation period. The covariate-adjusted hazard ratio for lean core muscle area was 1.45 (P = 0.028), indicating that mortality increased by 45% per 1000 mm(2) decrease in lean core muscle area. When stratified into tertiles of core muscle size, the 1-year survival was 87% versus 95% for the smallest versus largest tertile, whereas the 3-year survival was 75% versus 91%, respectively (P < 0.003 for both comparisons). The estimated average risk of complications significantly differed and was 20.9%, 15.0%, and 12.3% in the lower, middle, and upper tertiles of lean core muscle area, respectively. Covariate-adjusted cost increased significantly by an estimated $10,110 per 1000 mm(2) decrease in core muscle size (P = 0.003).

CONCLUSIONS

Core muscle size is an independent and potentially important preoperative risk factor. The techniques used to assess preoperative CT scans, namely analytic morphomics, may represent a novel approach to better understanding patient risk.

Nutrition support and infections associated with hepatic resection and liver transplantation in patients with chronic liver disease

Malnutrition is common in liver cirrhotic patients who will undergo liver resection or liver transplantation. A precise evaluation of their nutrition status is thus difficult because of the presence of ascites and the edema caused by their impaired protein synthesis. Both perioperative enteral and parenteral nutrition have benefits in reducing the morbidity and mortality of liver surgery, and in general, oral nutrition supplements are recommended. Branched-chain amino acids (BCAAs) promote protein and glycogen synthesis and regulate immune system function. Synbiotics, a combination of pro- and prebiotics, is reported to enhance immune responses. Oral nutrition support with BCAAs, synbiotics, and an immune-enhancing diet have a beneficial effect on preventing the perioperative infections associated with hepatic resection or liver transplantation.

Importance of lean body mass in the oncologic patient

Loss of lean body develops from an imbalance in protein synthesis and catabolism and is associated with a variety of different disease and nondisease states, including severe malnutrition, cachexia, and physiologic age-related loss (sarcopenia). Loss of lean body mass is prevalent among a significant proportion of the elderly population and has been associated with increased adverse clinical outcomes. Recognition of individuals at risk for low lean body mass may be difficult due to unequal distribution of losses across muscle and adipose compartments, and individuals who are both obese and sarcopenic demonstrate the highest risk for adverse events. Cross-sectional imaging modalities provide an accessible and easily interpretable means of quantifying lean muscle content and are routine diagnostic tests for cancer patients. As a result, a growing body of literature has developed characterizing the importance of low lean body mass as a poor prognostic factor among cancer patients, regardless of age. Cancer patients, especially those with sarcopenic obesity, are at increased risk for treatment-related toxicities from chemotherapy and increased overall mortality. Further investigations into the pathogenesis of muscle wasting among cancer patients are critical, as therapeutic oncologic interventions may inadvertently accelerate muscle catabolism. This review provides an overview of the definitions of low lean body mass, etiologic causes, clinical significance among cancer patients, and potential therapeutic interventions.

Impact of sarcopenia on outcomes following resection of pancreatic adenocarcinoma

INTRODUCTION

Assessing patient-specific risk factors for long-term mortality following resection of pancreatic adenocarcinoma can be difficult. Sarcopenia--the measurement of muscle wasting--may be a more objective and comprehensive patient-specific factor associated with long-term survival.

METHODS

Total psoas area (TPA) was measured on preoperative cross-sectional imaging in 557 patients undergoing resection of pancreatic adenocarcinoma between 1996 and 2010. Sarcopenia was defined as the presence of a TPA in the lowest sex-specific quartile. The impact of sarcopenia on 90-day, 1-year, and 3-year mortality was assessed relative to other clinicopathological factors.

RESULTS

Mean patient age was 65.7 years and 53.1 % was male. Mean TPA among men (611 mm²/m²) was greater than among women (454 mm²/m²). Surgery involved pancreaticoduodenectomy (86.0 %) or distal pancreatectomy (14.0 %). Mean tumor size was 3.4 cm; 49.9 % and 88.5 % of patients had vascular and perineural invasion, respectively. Margin status was R0 (59.0 %) and 77.7 % patients had lymph node metastasis. Overall 90-day mortality was 3.1 % and overall 1- and 3-year survival was 67.9 % and 35.7 %, respectively. Sarcopenia was associated with increased risk of 3-year mortality (HR = 1.68; P < 0.001). Tumor-specific factors such as poor differentiation on histology (HR = 1.75), margin status (HR = 1.66), and lymph node metastasis (HR = 2.06) were associated with risk of death at 3-years (all P < 0.001). After controlling for these factors, sarcopenia remained independently associated with an increased risk of death at 3 years (HR = 1.63; P < 0.001).

CONCLUSIONS

Sarcopenia was a predictor of survival following pancreatic surgery, with sarcopenic patients having a 63 % increased risk of death at 3 years. Sarcopenia was an objective measure of patient frailty that was strongly associated with long-term outcome independent of tumor-specific factors.

Advanced age affects the outcome-predictive power of RIFLE classification in geriatric patients with acute kidney injury

The RIFLE (risk, injury, failure, loss, and end-stage) classification is widely used to gauge the severity of acute kidney injury, but its efficacy has not been formally tested in geriatric patients. To correct this we conducted a prospective observational study in a multicenter cohort of 3931 elderly patients (65 years of age or older) who developed acute kidney injury in accordance with the RIFLE creatinine criteria after major surgery. We studied the predictive power of the RIFLE classification for in-hospital mortality and investigated the potential interaction between age and RIFLE classification. In general, the survivors were significantly younger than the nonsurvivors and more likely to have hypertension. In patients 76 years of age and younger, RIFLE-R, -I, or -F classifications were significantly associated with increased hospital mortality in a stepwise manner. There was no significant difference, however, in hospital mortality in those over 76 years of age between patients with RIFLE-R and RIFLE-I, although RIFLE-F patients had significantly higher mortality than both groups. Thus, the less severe categorizations of acute kidney injury per RIFLE classification may not truly reflect the adverse impact on elderly patients.

Selecting lung transplant candidates: where do current guidelines fall short?

In 2010, 1770 lung transplant procedures were performed in the USA, yet 2469 new candidates were added to the waiting list the same year. The shortage of suitable donor lungs requires that transplant professionals select patients for lung transplantation only if they are likely to sustain a survival benefit from the procedure. However, 20% of lung transplant recipients die within the first year of transplantation, suggesting that we are failing to identify those at high risk for severe early complications. In this perspective, we review the current guidelines for the selection of lung transplant candidates, which are based largely on expert opinion and small case series. We also propose the study of new extrapulmonary factors, such as frailty and sarcopenia, that might help improve the prediction of complications and early death after lung transplantation, leading to an improved candidate selection process.

Hypoalbuminemia and early mortality after lung transplantation: a cohort study

Hypoalbuminemia predicts disability and mortality in patients with various illnesses and in the elderly. The association between serum albumin concentration at the time of listing for lung transplantation and the rate of death after lung transplantation is unknown. We examined 6808 adults who underwent lung transplantation in the United States between 2000 and 2008. We used Cox proportional hazard models and generalized additive models to examine multivariable-adjusted associations between serum albumin and the rate of death after transplantation. The median follow-up time was 2.7 years. Those with severe (0.5-2.9 g/dL) and mild hypoalbuminemia (3.0-3.6 g/dL) had posttransplant adjusted mortality rate ratios of 1.35 (95% CI: 1.12-1.62) and 1.15 (95% CI: 1.04-1.27), respectively. For each 0.5 g/dL decrease in serum albumin concentration the 1-year and overall mortality rate ratios were 1.48 (95% CI: 1.21-1.81) and 1.26 (95% CI: 1.11-1.43), respectively. The association between hypoalbuminemia and posttransplant mortality was strongest in recipients with cystic fibrosis and interstitial lung disease. Hypoalbuminemia is an independent risk factor for death after lung transplantation.

Chronology of age-related disease definitions: osteoporosis and sarcopenia

Low muscle mass at older age has been associated with functional impairments, cognitive decline and mortality. The term sarcopenia, coined in 1988, has been used interchangeably to describe low muscle mass, strength, and function. Without a well defined definition, results of studies using the term sarcopenia cannot be compared. Difficulties in defining sarcopenia parallel the history of defining osteoporosis. To understand critical steps that are needed to reach consensus in defining age-related diseases, we have identified milestones in the history of defining osteoporosis and compared these to sarcopenia. As a result, the main missing steps in the process of defining sarcopenia are: specific treatment options, pharmaceutical interest, and public awareness. Similar to osteoporosis being defined as 'low bone mineral density', the term sarcopenia should be reserved for 'low muscle mass'. Consensus must be reached regarding the diagnostic criteria to quantify muscle mass, correction factors, and reference populations used to define cut-off values of muscle mass.

The advantages and limitations of cross-sectional body composition analysis

PURPOSE OF REVIEW

Cross-sectional (C-S) imaging is now commonly used to measure body composition in clinical studies. This review highlights the advantages, limitations and suggested future directions for this technique.

RECENT FINDINGS

Current understanding of C-S imaging reproducibility, tissue identification and segmentation methods, comparison between imaging techniques and estimates of whole body composition using a single image are described.

SUMMARY

C-S imaging can reliably measure muscle and fat distribution and uniquely discriminate between intra-abdominal organ and muscle component of fat-free mass. It precisely tracks changes within an individual, but is less able to distinguish true differences in whole body estimates between individuals.

Late evening snack: exploiting a period of anabolic opportunity in cirrhosis

BACKGROUND AND AIM

Cirrhosis is a state of accelerated starvation with impaired protein synthesis. Increased rate of gluconeogenesis and alterations in skeletal muscle signaling pathways result in anabolic resistance and consequent loss of muscle mass or sarcopenia in cirrhosis. Late evening snack (LES) is an intervention to reduce the postabsorptive (fasting) phase with the potential to improve substrate utilization and reverse sarcopenia. Published reports were evaluated to examine the effect of LES on regulation of substrate utilization (short-term studies) and nutritional outcomes (long-term studies).

METHODS

PubMed, EMBASE, Google scholar and OVID databases were searched. All studies published on LES in cirrhosis were included. Studies that included few (n < 3) subjects and patients with hepatocellular carcinoma were excluded.

RESULTS

Late evening snack decreased lipid oxidation and improved nitrogen balance, irrespective of the composition or type of formulation used. Daytime isocaloric isonitrogenous snacks did not have the metabolic or clinical benefit of LES. LES decreased skeletal muscle proteolysis. No studies have examined its effect on muscle protein synthesis. There was inconsistent translation into an increase in lean body or skeletal muscle mass. Improved quality of life occurs but decreased mortality or need for transplantation has not been reported. The optimal composition of LES has not been defined, but based on mechanistic considerations, a branched chain supplemented LES holds most promise.

CONCLUSIONS

Late evening snack holds the most promise as an intervention to reverse anabolic resistance and sarcopenia of cirrhosis with improved quality of life in patients with cirrhosis. Long term benefit and improved survival need critical evaluation.

A quantitative tool to assess degree of sarcopenia objectively in patients with hypercortisolism

BACKGROUND

Muscle weakness and wasting are known manifestations of hypercortisolism (HC). Central sarcopenia is a marker of frailty and predicts mortality. The hypothesis of this study is that central sarcopenia can be used as a marker of disease severity and frailty in patients with HC.

METHODS

Psoas muscle area and psoas muscle density (PMD) were measured at specific points on CT scans of patients with HC using a defined protocol. We compared 24-hour urine cortisol (24HUC) levels by time point to each CT scan. A linear regression model was used to describe the relationship between 24HUC and morphometric variables. A comparison with matched non-HC patients was performed.

RESULTS

We identified 45 patients (34 female). The median age was 46 years (range, 14-80); the median 24HUC was 211 mg/dL (range, 9.5-39,500); the median PMD was 50.1 24HUC (range, 20-72). An inverse correlation (-0.29) between 24HUC levels and PMD was noted (P = .045). Intra-abdominal fat was also significantly and positively correlated with 24HUC: 27 non-HC patients matched for age, sex, and body-mass index showed higher (58 vs 51) PMD (P = .0127) compared to those with HC.

CONCLUSION

PMD and intra-abdominal fat are significantly related to 24HUC levels. Morphometric measures of the overall burden of HC may allow more precise assessment of disease severity.

Malnutrition in cirrhosis: contribution and consequences of sarcopenia on metabolic and clinical responses

Malnutrition is the most common, reversible complication of cirrhosis that adversely affects survival, response to other complications, and quality of life. Sarcopenia, or loss of skeletal muscle mass, and loss of adipose tissue and altered substrate use as a source of energy are the 2 major components of malnutrition in cirrhosis. Current therapies include high protein supplementation especially as a late evening snack. Exercise protocols have the potential of aggravating hyperammonemia and portal hypertension. Recent advances in understanding the molecular regulation of muscle mass has helped identify potential novel therapeutic targets including myostatin antagonists, and mTOR resistance.

Body composition and outcome in patients undergoing resection of colorectal liver metastases

BACKGROUND

Recent evidence suggests that depletion of skeletal muscle mass (sarcopenia) and an increased amount of intra-abdominal fat (central obesity) influence cancer statistics. This study investigated the impact of sarcopenia and central obesity on survival in patients undergoing liver resection for colorectal liver metastases (CLM).

METHODS

Diagnostic imaging from patients who had hepatic resection for CLM in one centre between 2001 and 2009, and who had assessable perioperative computed tomograms, was analysed retrospectively. Total cross-sectional areas of skeletal muscle and intra-abdominal fat, and their influence on outcome, were analysed.

RESULTS

Of the 196 patients included in the study, 38 (19·4 per cent) were classified as having sarcopenia. Five-year disease-free (15 per cent versus 28·5 per cent in patients without sarcopenia; P = 0·002) and overall (20 per cent versus 49·9 per cent respectively; P < 0·001) survival rates were lower for patients with sarcopenia at a median follow-up of 29 (range 1-97) months. Sarcopenia was an independent predictor of worse recurrence-free (hazard ratio (HR) 1·88, 95 per cent confidence interval 1·25 to 2·82; P = 0·002) and overall (HR 2·53, 1·60 to 4·01; P < 0·001) survival. Central obesity was associated with an increased risk of recurrence in men (P = 0·032), but not in women (P = 0·712).

CONCLUSION

Sarcopenia has a negative impact on cancer outcomes following resection of CLM.

Development of a quantitative method for the diagnosis of cirrhosis

OBJECTIVE

To develop a novel non-invasive, quantitative approach utilizing computed tomography scans to predict cirrhosis.

MATERIALS AND METHODS

A total of 105 patients (54 cirrhosis and 51 normal) who had CT scans within 6 months of a liver biopsy or were identified through a Trauma registry were included in this study. Patients were randomly divided into the training set (n = 81) and the validation set (n = 24). Each liver was segmented in a semi-automated fashion from a computed tomography scan using Mimics software. The resulting liver surfaces were saved as a stereo lithography mesh into an Oracle database, and analyzed in MATLAB(®) for morphological markers of cirrhosis.

RESULTS

The best predictive model for diagnosing cirrhosis consisted of liver slice-bounding box slice ratio, the dimensions of the liver bounding box, liver slice area, slice perimeter, surface volume and adjusted surface area. With this model, we calculated an area under the receiver operating characteristic curve of 0.90 for the training set, and 0.91 for the validation set. For comparison, we calculated an area under the receiver operating characteristic curve of 0.70 for our dataset when we used the lab value based aspartate aminotransferase-platelet ratio index, another reported model for predicting cirrhosis. Last, by combining the aspartate aminotransferase-platelet ratio index and our model, we obtained an area under the receiving operating characteristic of 0.95.

CONCLUSION

This study shows "proof of concept" that quantitative image analysis of livers on computed tomography scans may be utilized to predict cirrhosis in the absence of a liver biopsy.

Changes in body composition after transjugular intrahepatic portosystemic stent in cirrhosis: a critical review of literature

Change in body composition with reduced muscle mass with or without loss of fat mass occurs in 60-90% of patients with cirrhosis. This has an adverse impact on the outcome of these patients and is an understudied area. Transjugular intrahepatic portosystemic stent (TIPS) is now a standard therapy for portal hypertension but its beneficial impact on nutritional indices is not well recognized. We included all publications on TIPS that had any nutritional index as an outcome measure or end point. Given the heterogeneity of the patient population, differences in study design and outcome measures, a meta-analysis was not feasible. Data were summarized and interpreted. A total of eight studies have been published on the changes in body composition after TIPS in cirrhosis in a total of 152 patients followed for 3-12 months. Improvement in fat-free mass and fluid-free or ascites-free body weight was reported in all studies. Plasma leptin, IGF1, insulin sensitivity, rate of glucose disposal and growth hormone did not change after TIPS. One study measured muscle strength that improved. Direct measurement of skeletal muscle mass was not performed in any study. TIPS resulted in an improvement in body composition. Given the clinical significance of skeletal muscle and fat mass in cirrhosis, nutritional indices should be considered to be an important outcome measure in patients with TIPS. The mechanism of these is unclear, but its clinical implication is that this may contribute to the improved survival after TIPS.

Surgical site infection and analytic morphometric assessment of body composition in patients undergoing midline laparotomy

BACKGROUND

Obesity is a known risk factor for surgical site infection (SSI). Our hypothesis is that morphometric measures of midline subcutaneous fat will be associated with increased risk of SSI and will predict SSI better than conventional measures of obesity.

STUDY DESIGN

We identified 655 patients who underwent midline laparotomy (2006 to 2009) using the Michigan Surgical Quality Collaborative database. Using novel, semiautomated analytic morphometric techniques, the thickness of subcutaneous fat along the linea alba was measured between T12 and L4. To adjust for variations in patient size, subcutaneous fat was normalized to the distance between the vertebrae and anterior skin. Logistic regression analyses were used to identify factors independently associated with the incidence of SSI.

RESULTS

Overall, SSIs were observed in 12.5% (n = 82) of the population. Logistic regression revealed that patients with increased subcutaneous fat had significantly greater odds of developing a superficial incisional SSI (odds ratio [OR] = 1.76 per 10% increase, 95% CI 1.10 to 2.83, p = 0.019). Smoking, steroid use, American Society of Anesthesiologists (ASA) classification, and incision-to-close operative time were also significant independent risk factors for superficial incisional SSI. When comparing subcutaneous fat and body mass index (BMI) as the only model variables, subcutaneous fat significantly improved model predictions of superficial incisional SSI (area under the receiver operating characteristic curve [AUC] 0.60, p = 0.023); BMI did not (AUC 0.52, p = 0.73).

CONCLUSIONS

Abdominal subcutaneous fat is an independent predictor of superficial incisional SSI after midline laparotomy. Novel morphometric measures may improve risk stratification and help elucidate the pathophysiology of surgical complications.

Sarcopenia negatively impacts short-term outcomes in patients undergoing hepatic resection for colorectal liver metastasis

BACKGROUND

As indications for liver resection expand, objective measures to assess the risk of peri-operative morbidity are needed. The impact of sarcopenia on patients undergoing liver resection for colorectal liver metastasis (CRLM) was investigated.

METHODS

Sarcopenia was assessed in 259 patients undergoing liver resection for CRLM by measuring total psoas area (TPA) on computed tomography (CT). The impact of sarcopenia was assessed after controlling for clinicopathological factors using multivariate modelling.

RESULTS

Median patient age was 58 years and most patients (60%) were male. Forty-one (16%) patients had sarcopenia (TPA ≤ 500 mm(2) /m(2) ). Post-operatively, 60 patients had a complication for an overall morbidity of 23%; 26 patients (10%) had a major complication (Clavien grade ≥3). The presence of sarcopenia was strongly associated with an increased risk of major post-operative complications [odds ratio (OR) 3.33; P= 0.008]. Patients with sarcopenia had longer hospital stays (6.6 vs. 5.4 days; P= 0.03) and a higher chance of an extended intensive care unit (ICU) stay (>2 days; P= 0.004). On multivariate analysis, sarcopenia remained independently associated with an increased risk of post-operative complications (OR 3.12; P= 0.02). Sarcopenia was not significantly associated with recurrence-free [hazard ratio (HR) = 1.07] or overall (HR = 1.05) survival (both P > 0.05).

CONCLUSIONS

Sarcopenia impacts short-, but not long-term outcomes after resection of CRLM. While patients with sarcopenia are at an increased risk of post-operative morbidity and longer hospital stay, long-term survival is not impacted by the presence of sarcopenia.