OBJECTIVES: We evaluated the validity and reliability of ultrasonography measurement of rectus femoris cross-sectional area compared to computed tomography in patients in pre-dialysis chronic kidney disease and analyzed the association between these measurements and the diagnosis of sarcopenia. METHODS: One hundred patients with nondialysis chronic kidney disease were evaluated. Sarcopenia was defined using the criteria of the Foundation for the National Institutes of Health Sarcopenia Project (FNIH). The rectus femoris cross-sectional area was evaluated using ultrasonography and computed tomography. RESULTS: The prevalence of sarcopenia was 29% according to the FNIH criteria. The difference in mean rectus femoris cross-sectional area by ultrasonography and computed tomography was 3.97 mm, with a strong correlation between the two methods (p<0.001). Bland-Altman plot analysis showed good agreement between computed tomography and ultrasonography. Rectus femoris cross-sectional area was significantly correlated with muscle strength (r=0.300, p=0.002), lean body mass in the upper limbs (r=0.286, p=0.004), and lean body mass in the lower limbs (r=0.271, p=0.006). The prevalence of sarcopenia was 12% (n=12) based on the definition of low muscle mass according to ultrasonography of the rectus femoris cross-sectional area. CONCLUSION: Ultrasonography was demonstrated to be a valid and reliable method for evaluating the rectus femoris cross-sectional area in patients in pre-dialysis chronic kidney disease.

Introdução: Inúmeros estudos avaliaram as associações entre fatores sociodemográficos, econômicos e doença renal crônica (DRC) e demonstraram que essas associações foram complexas e multifatoriais. Um método para avaliar os fatores socioeconômicos é construir um modelo de vulnerabilidade social (VS). Objetivo: Identificar a influência de vulnerabilidade social (VS) sobre os desfechos de uma coorte de pacientes com doença renal crônica (DRC) pré-dialítica. Métodos: Foram coletados dados demográficos, clínicos e laboratoriais, em uma coorte retrospectiva com pacientes nos estágios 3 a 5, que foram acompanhados por uma equipe interdisciplinar, no período compreendido entre janeiro de 2002 e dezembro de 2009, em Minas Gerais, Brasil. Para calcular a VS, foram utilizadas três técnicas estatísticas em sequência, análise fatorial, análise de agrupamento e análise discriminante. A sobrevida foi analisada com as curvas de Kaplan-Meier. O desfecho foi mortalidade ou iniciar a terapia renal substitutiva (TRS), analisadas por uma regressão de Cox. Resultados: Foram avaliados 209 pacientes, 29,4% eram vulneráveis. Não observamos diferença na mortalidade entre os grupos VS pela Kaplan Meier. Na regressão de Cox, hazard ratio (HR) e intervalo de confiança (CI) para o impacto da VS sobre a mortalidade, não ajustado foi HR: 1.87 (CI: 0.64-5 0,41) e HR ajustado:1,47 (C1: 0.35-60,0). O impacto da VS em TRS mostrou o HR e CI HR não ajustado: 1,85 (CI: 0.7140,8) e HR ajustado: 2,19 (CI: 0.50-90,6). Conclusão: Estes resultados indicam que a VS não influenciou os resultados de pacientes com DRC na pré-diálise tratados em um centro interdisciplinar.

Introduction: Numerous studies examined the associations between socio-demographic, economic and individual factors and chronic kidney disease (CKD) outcomes and observed that the associations were complex and multifactorial. Socioeconomic factors can be evaluated by a model of social vulnerability (SV). Objective: To analyze the impact of SV on the outcomes of predialysis patients. Methods: Demographic, clinical and laboratory data were collected from a cohort of patients with predialysis stage 3 to 5 who were treated by an interdisciplinary team (January 2002 and December 2009) in Minas Gerais, Brazil. Factor, cluster and discriminant analysis were performed in sequence to identify the most important variables and develop a model of SV that allowed for classification of the patients as vulnerable or non-vulnerable. Cox regression was performed to examine the impact of SV on the outcomes of mortality and need for renal replacement therapy (RRT). Results: Of the 209 patients examined, 29.4% were classified as vulnerable. No significance difference was found between the vulnerable and non-vulnerable groups regarding either mortality (log rank: 0.23) or need for RRT (log rank: 0.17). In the Cox regression model, the hazard ratios (HRs) for the unadjusted and adjusted impact of SV on mortality were found to be 1.87 (confidence interval [CI]: 0.64-5.41) and 1.47 (CI: 0.35-6.0), respectively, and the unadjusted and adjusted impact of need for RRT to be 1.85 (CI: 0.71-4.8) and 2.19 (CI: 0.50-9.6), respectively. Conclusion: These findings indicate that SV did not influence the outcomes of patients with predialysis CKD treated in an interdisciplinary center.

A sarcopenia é uma condição crônica associada ao processo fisiológico de envelhecimento e é definida pela redução da massa, força e função musculares. Na Doença Renal Crônica (DRC), a sarcopenia é prevalente, e associa-se ao aumento da morbimortalidade e à ocorrência de complicações cardiovasculares. Ao analisarmos a sarcopenia em pacientes com insuficiência renal, destacam-se mecanismos complexos que contribuem para a perda de massa muscular, como ativação de mediadores que estimulam o sistema da ubiquitina-proteossoma (SUP) dependente de ATP, inflamação, acidose metabólica, angiotensina II e alguns fatores hormonais. A abordagem terapêutica da sarcopenia na DRC inclui a realização de exercícios, correção da acidose metabólica, reposição hormonal e tratamento da resistência insulínica. Desta forma, é de suma importância o reconhecimento precoce da sarcopenia nesta população, com o intuito de estabelecer intervenções terapêuticas eficazes, evitando-se, assim, toda a gama de complicações associadas à perda de massa muscular na DRC.

Sarcopenia is a chronic condition associated with physiological aging process and is defined by the reduction of the mass, muscle strength and function. In Chronic Kidney Disease (CKD), sarcopenia is prevalent and is associated with increased morbidity and mortality and the occurrence of cardiovascular complications. By analyzing sarcopenia in patients with renal insufficiency, complex mechanisms that contribute to loss of muscle mass are highlighted, such as activation of mediators that stimulate the ubiquitin-proteasome system (SUP) ATP-dependent, inflammation, metabolic acidosis, angiotensin II and some hormonal factors. The therapeutic approach to sarcopenia in CKD includes exercises, correction of metabolic acidosis, hormone replacement therapy and insulin resistance. Thus, it is of paramount importance early recognition of sarcopenia in this population, in order to establish effective therapeutic interventions, thus avoiding the full range of complications associated with muscle wasting in CKD.