Assessment of body composition using dual energy x-ray absorptiometry in patients with liver cirrhosis: comparison with anthropometry

Obesity as predictor of postoperative outcomes in liver transplant candidates: Review of the literature and future perspectives

BACKGROUND

Current American and European guidelines consider a pre-transplant BMI ≥40kg/m² as a relative contraindication for liver transplantation but this recommendation is graded as uncertain and requires further research. Moreover, conflicting results are reported on the predictive value of BMI 30-39.9kg/m² on post-transplant complication and mortality risk.

AIM

This study analyzed the data of the literature on the effect of all three BMI classes of obesity on postoperative outcomes in liver transplantation.

MATERIALS AND METHODS

A PubMed and Cochrane Library search was conducted from inception to October 2015.

RESULTS

Analysis of the literature demonstrates that discrepancies among studies are mainly either due to limitations of BMI per se, the different BMI cut-offs used to select patients with obesity or reference group and the different outcomes considered. Moreover, the evaluation of visceral adipose tissue and the detrimental effect of muscle mass reduction in presence of obesity are never considered.

CONCLUSIONS

BMI assessment should be used as a preliminary method to evaluate obesity. Subsequently, the assessment of visceral adipose tissue and muscle mass should complete the preoperative evaluation of liver transplant candidates. This innovative approach could represent a new field of research in liver transplantation.

Improved 4-compartment body-composition model for a clinically accessible measure of total body protein

BACKGROUND

Muscle wasting is a consequence of many primary conditions including sarcopenia, cachexia, osteoporosis, HIV/AIDS, and chronic kidney disease. Unfortunately, there is not a clinically accessible method to measure total body protein, which is the functional mass of muscle.

OBJECTIVE

We sought to derive a simple method to measure total body protein by using dual-energy X-ray absorptiometry (DXA) and bioimpedance analysis (BIA).

DESIGN

We retrospectively analyzed a clinical convenience sample of individuals with numerous metabolic conditions from the Monash Medical Centre, Melbourne, Australia, who had a concurrent protein measure by using neutron activation analysis-derived protein (NAA-TBPro), water measure by using BIA, and whole-body DXA scan. The study was split into calibration and validation data sets by using simple random sampling stratified by sex, BMI category, and age decade. We generated a protein estimate direct-calibration protein (DC-TBPro) derived from BIA water, bone mass, and body volume. We compared NAA-TBPro with DC-TBPro and 2 protein estimates from the literature, one that used the DC-TBPro equation with fixed coefficients [4-compartment Lohman method for analysis of total body protein (4CL-TBPro)] and another that used fat-free mass, age, and sex [Wang equation-derived protein (W-TBPro)].

RESULTS

A total of 187 participants [119 women; mean (±SD) age: 37.0 ± 15.4 y; mean (±SD) BMI (in kg/m(2)) 24.5 ± 7.7] were included. When plotted against NAA-TBPro, DC-TBPro had the highest correlation [coefficient of determination (R(2)) = 0.87], lowest root mean squared error (RMSE; 0.87 kg), and fewest outliers compared with 4CL-TBPro (R(2) = 0.75; RMSE = 1.22 kg) and W-TBPro (R(2) = 0.80; RMSE = 1.10 kg).

CONCLUSIONS

A simple method to measure total body protein by using a DXA system and BIA unit was developed and compared with NAA as proof of principle. With additional validation, this method could provide a clinically useful way to monitor muscle-wasting conditions.

Evaluation of arm anthropometry for assessing pediatric body composition: evidence from healthy and sick children

Arm anthropometry is used as a proxy of body composition in clinical and field research but its validity has not been established in children. To address this issue, mid-upper arm circumference (MUAC) and triceps skinfold thickness (TS) were measured in 110 healthy children aged 4.4-13.9 y (55 boys) and 49 cystic fibrosis (CF) patients aged 8.1-13.4 y (22 boys). Reference values were arm and whole-body fat mass (FM) and fat-free mass (FFM) measured by dual x-ray absorptiometry and four-component model, respectively. Arm fat area (AFA), MUAC, and TS correlated well with arm FM (r = 0.84-0.92) and total FM (r = 0.78-0.92). Arm muscle area (AMA) and MUAC correlated well with arm FFM (r = 0.68-0.82) and total FFM (r = 0.60-0.86). After adjusting for age, sex, and height, arm anthropometry correlated strongly with FM but weakly with FFM. AFA, MUAC, and TS explained 67, 63, and 61% of variability in total FM in healthy children and 70, 72, and 63% in CF. AMA and MUAC explained only 24 and 16% of variability in total FFM in healthy children and 33 and 28% in CF. Arm anthropometry is useful for predicting FM and ranking healthy children and patients for fatness. It has poorer success in predicting regional or total FFM.

Sensibilidade de indicadores da desnutrição protéico-energética em cirróticos com vários graus de disfunção hepatocelular

OBJETIVO: A sensibilidade de indicadores antropométricos e laboratoriais, na detecção da desnutrição protéico-energética de cirróticos foi estudada em 117 adultos, com gravidades (Child-Pugh), Child A (18), B (42) e C (57). RESULTADOS: Os indicadores antropométricos mais alterados foram: a circunferência braquial 61%, a prega cutânea tricipital 55% e a prega cutânea subescapular 53%, e os laboratoriais: albumina 93% e hemoglobina 90%. Com a combinação de indicadores circunferência braquial + prega cutânea subescapular + albumina ou hemoglobina, alcançaram-se 29% de déficit, valor idêntico ao da associação apenas de circunferência braquial + prega cutânea subescapular. Essa combinação (circunferência braquial e prega cutânea subescapular) detectou 63% de desnutrição protéico-energética, com predominância das formas moderada e grave em todos os graus Child. CONCLUSÃO: A desnutrição protéico-energética na cirrose hepática é predominantemente protéica, podendo ser caracterizada por indicadores laboratoriais (mais sensíveis) ou, com maior especificidade, pela circunferência braquial, embora inespecífica à discriminação da gravidade da desnutrição protéico-energética entre os grupos Child B e C.

Nutritional aspects of liver disease and transplantation

In the past year, some relevant papers related to the diagnosis of malnutrition and its pathogenesis in cirrhosis have been published. The value of anthropometrics in the nutritional assessment of end-stage cirrhotic patients has been reinforced. Also, the role of bioelectrical impedance analysis in these patients has been redefined. Several papers have investigated the relationship between leptin and malnutrition in chronic liver disease, particularly the role of alcoholism in hyperleptinaemia, and the importance of protein-bound leptin in these patients. In other papers, the impact of both undernutrition and obesity on the outcome of liver transplantation has been investigated. Two randomized, controlled trials on enteral nutrition in liver disease have been published in this period. One of them deals with a clinical situation (i.e. severe alcoholic hepatitis) associated with a high mortality rate, whereas the second is the first controlled trial in the field of preoperative nutrition in liver transplantation. Finally, some papers provide further arguments in the dilemma of which route of nutrition (enteral or parenteral) is better in cirrhosis.

Nutritional and metabolic issues in cirrhosis and liver transplantation

In the last year some relevant papers on nutrition and metabolism in chronic liver disease and transplantation have been published. Studies investigating the reliability of predicting energy expenditure in cirrhosis, and some relevant contributions to the understanding of metabolic consequences of liver transplantation, deserve particular mention. These include the first direct evidence that liver transplantation corrects the insulin resistance present in cirrhosis, as well as studies on the role of genetic polymorphism of the vitamin D receptor gene in bone loss after transplantation. Other papers have dealt with body composition, polyunsaturated fatty acid and antioxidant status in cirrhosis. However, relevant contributions in the field of nutritional support in cirrhosis are surprisingly lacking.