Influence of hormonal status and oral intake on phase angle in HIV-infected men

Decreased IGF-1 levels potentiate association of inflammation with all-cause and cardiovascular mortality in prevalent hemodialysis patients

OBJECTIVE

Insulin-like growth factor-1 (IGF-1) and inflammation have both been linked to high cardiovascular risk and mortality in the general population, as well as in hemodialysis (HD) patients. We hypothesized that the association of low IGF-1 with chronic inflammation may increase the mortality risk in HD patients.

DESIGN

We investigated the interactions between inflammatory biomarkers (IL-6 and TNF-α) and IGF-1 as predictors of death over a 4 years of follow-up (median--47 months, interquartile range--17.5-75 months) in 96 prevalent HD patients (35% women, mean age of 64.9 ± 11.6 years).

RESULTS

A significant interaction effect of low IGF-1 (defined as a level less than median) and high IL-6 (defined as a level higher than median) on all-cause and cardiovascular mortality was found: crude Cox hazard ratios (HR) for the product termed IGF-1 × IL-6 were 4.27, with a 95% confidence interval (CI): 2.10 to 8.68 (P<0.001) and 7.49, with a 95% CI: 2.40-24.1 (P=0.001), respectively. Across the four IGF-1-IL-6 categories, the group with low IGF-1 and high IL-6 exhibited the worse outcome in both all-cause and cardiovascular mortality (multivariable adjusted hazard ratios were 4.92, 95% CI 1.86 to 13.03, and 14.34, 95% CI 1.49 to 137.8, respectively). The main clinical characteristics of patients in the low-IGF-1-high IL-6 group didn't differ from other IGF-1-IL-6 categorized groups besides gender that consequently was inserted in all multivariable models together with the other potential confounders.

CONCLUSIONS

An increase in mortality risk was observed in HD patients with low IGF-1 and high IL-6 levels, especially cardiovascular causes.

Bioelectrical phase angle and impedance vector analysis--clinical relevance and applicability of impedance parameters

BACKGROUND & AIMS

The use of phase angle (PhA) and raw parameters of bioelectrical impedance analysis (BIA) has gained attention as alternative to conventional error-prone calculation of body composition in disease. This review investigates the clinical relevance and applicability of PhA and Bioelectrical Impedance Vector Analysis (BIVA) which uses the plot of resistance and reactance normalized per height.

METHODS

A comprehensive literature search was conducted using Medline identifying studies relevant to this review until March 2011. We included studies on the use of PhA or BIVA derived from tetrapolar BIA in out- and in-patient settings or institutionalized elderly.

RESULTS

Numerous studies have proven the prognostic impact of PhA regarding mortality or postoperative complications in different clinical settings. BIVA has been shown to provide information about hydration and body cell mass and therefore allows assessment of patients in whom calculation of body composition fails due to altered hydration. Reference values exist for PhA and BIVA facilitating interpretation of data.

CONCLUSION

PhA, a superior prognostic marker, should be considered as a screening tool for the identification of risk patients with impaired nutritional and functional status, BIVA is recommended for further nutritional assessment and monitoring, in particular when calculation of body composition is not feasible.

Bioimpedância elétrica e sua aplicação em avaliação nutricional

A busca por métodos de estimativa da composição corporal é uma preocupação constante da comunidade científica, com vistas à obtenção de um acurado diagnóstico do estado nutricional de indivíduos e populações. A bioimpedância elétrica tem sido uma alternativa atraente na avaliação da composição corporal, pela possibilidade de se trabalhar com equipamento não invasivo, portátil, de fácil manuseio, boa reprodutibilidade e, portanto, viável para a prática clínica e para estudos epidemiológicos. Sua utilização, que tem como finalidade determinar o fracionamento da composição corporal, tem sido apontada como uma técnica capaz de superar alguns desafios encontrados em outros métodos para avaliar o estado nutricional. Entre os componentes da bioimpedância elétrica, o ângulo de fase consiste em uma ferramenta cada vez mais utilizada na prática clínica, sendo estudado como indicador prognóstico e de estado nutricional. Esse ângulo indica alterações na composição corporal e na função da membrana celular, portanto, no estado de saúde de indivíduos. Dada a carência de estudos brasileiros sobre determinadas aplicações da bioimpedância elétrica, a proposta deste estudo, buscando contribuir com a literatura, é traçar um panorama sobre o emprego dessa técnica e, ainda, apresentar trabalhos que a comparam com outros métodos de avaliação nutricional e composição corporal.

Macronutrient supplementation and food prices in HIV treatment

Infection caused by HIV and malnutrition have a complex interaction and often coexist geographically. Malnutrition has synergistic immune effects and HIV affects nutritional status. HIV care and treatment programs are compelled to confront this dual burden to optimize HIV outcomes. In this article, we review the published literature concerning intervention studies in adults and children and the effect of food prices on HIV treatment programs. While the evidence base is relatively incomplete for specific macronutrient interventions in the context of HIV treatment, it is clear that a new standard of care is needed, guided by experience, rationale, and existing data, in which malnourished patients may easily access nutritional therapies within HIV treatment. From this clinical foundation, we may both treat patients and evaluate novel therapies. Some HIV care and treatment programs provide food-based supplements; however, rising food costs and economic instability may jeopardize the success of these programs. HIV treatment programs may struggle to meet the needs of patients with potential increased rates of malnutrition and food insecurity in the setting of high food prices.

Bioelectrical impedance and strength measurements in patients with heart failure: comparison with functional class

OBJECTIVE

Patients with chronic heart failure (HF) develop important changes in body composition. Nevertheless, the usual methods of body composition assessment can be misleading in patients with HF because tissue hydration is altered. Bioelectrical impedance vector analysis (BIVA) works without making any assumption about constant soft tissue hydration. In this study, patients with HF and systolic dysfunction (HFS) and preserved systolic function (HFPSF) underwent a body composition evaluation by the BIVA method; the comparison was done between New York Heart Association (NYHA) functional classes I-II and III-IV.

METHODS

We studied 243 patients with HF, 140 (101 in NYHA I-II and 39 in III-IV) with HFS and 103 (67 in NYHA I-II and 36 in II-IV) with HFPSF. Whole-body bioelectrical impedance was measured using BodyStat QuadScan 4000, which is tetrapolar and multiple-frequency equipment.

RESULTS

In both HF categories, reactance and phase angle were significantly lower, the impedance ratio of 200 kHz to that at 5 kHz was higher, and had significantly shorter and downsloping impedance vector in the NYHA III-IV group compared with the NYHA I-II group by gender.

CONCLUSION

Bioelectrical impedance analysis allows an easier evaluation of body composition and this might be particularly useful to stratify the severity of HF.

Bioelectrical impedance analysis in clinical practice: a new perspective on its use beyond body composition equations

PURPOSE OF REVIEW

The bioelectrical impedance analysis is not a direct method for estimating body composition. Its accuracy depends on regression equations, and recent papers have suggested that this approach should not be used in several clinical situations. Another option is to obtain information about the electrical properties of tissues by using raw bioelectrical impedance measurements, resistance and reactance. They can be expressed as a ratio (phase angle) or as a plot (bioelectrical impedance vector analysis). This review describes their use in clinical practice.

RECENT FINDINGS

The phase angle changes with sex and age. It is described as a prognostic tool in many clinical situations. There are some controversies about considering it as a nutritional marker. Studies in burn victims and sickle-cell disease corroborate its ability to evaluate cell membrane function. Bioelectrical impedance vector analysis allows a semi-quantitative estimation of body composition from information from tissue hydration and soft-tissue mass in a plot. It can be used in healthy individuals or patients, for a population or individual evaluation of fluid imbalance or an assessment of soft-tissue mass. It has also been used as a prognostic tool in dialysis and cancer patients.

SUMMARY

The phase angle can be considered a global marker of health, and future studies are needed to prove its utility in intervention studies. Bioelectrical impedance vector analysis has increased its utility in clinical practice, even when the equations may be inaccurate for body composition analysis.