The impact of body mass index (BMI) variation on mortality of incident elderly patients on peritoneal dialysis: a joint model analysis / O impacto da variação do índice de massa corporal (IMC) na mortalidade de pacientes idosos incidentes em diálise peritoneal

Abstract Introduction: Data on impact of high body mass index (BMI) on mortality of patients on peritoneal dialysis (PD), especially among elderly, are inconsistent. Objective: To evaluate impact of BMI on cohort of incident elderly PD patients over time. Methods: Prospective multicenter cohort study (December / 2004-October/2007) with 674 patients. Socio-demographic and clinical data evaluated with patients followed until death, transfer to hemodialysis (HD), recovery of renal function, loss of follow-up or transplant. Patients were divided into incident on renal replacement therapy (RRT) for PD (PD first: 230) and transferred from hemodialysis (HD first: 444). Analysis was performed comparing these two groups using chi-square or Kruskal Wallis. Similar analysis was used to compare patients on automated peritoneal dialysis (APD) vs. continuous ambulatory peritoneal dialysis (CAPD). Data were compared between patients according to BMI by ANOVA, Kruskal Wallis or chi-square. For analysis of survival, Kaplan Meier method was used and to adjust confounding variables, Cox regression proportional hazard. Joint model for longitudinal and time-dependent data was conducted, assessing impact that a longitudinal variable displays on time of survival. Results: Malnourished patients (76.79 ± 7.53 years) were older (p < 0.0001) with higher percentage of death (44.6%, p = 0.001); diabetes mellitus showed high prevalence in obese patients (68%, p < 0.0001); higher blood pressure levels (p = 0.002) were present in obese and overweight patients. Conclusions: Increased BMI variation over time proved to be a protective factor, with a decrease of about 1% in risk of death for every BMI unit earned.

Resumo Introdução: Dados sobre o impacto do índice de massa corporal (IMC) sobre mortalidade de pacientes em diálise peritoneal (DP), especialmente entre os idosos, são inconsistentes. Objetivo: Avaliar o impacto do IMC sobre a mortalidade de coorte de pacientes incidentes idosos em DP ao longo do tempo. Métodos: Estudo de coorte prospectivo multicêntrico (dezembro de 2004 a outubro de 2007), com 674 pacientes. Avaliados dados sociodemográficos, clínicos e pacientes acompanhados até morte, transferência para hemodiálise (HD), recuperação da função renal, perda de seguimento ou transplante. Pacientes foram divididos em incidentes em terapia renal substitutiva por PD (230) e transferidos da hemodiálise (444). A análise foi feita comparando estes dois grupos usando Qui-Quadrado ou Kruskal Wallis. Análise semelhante foi utilizada para comparar os pacientes em diálise peritoneal automatizada vs. diálise peritoneal ambulatorial contínua. Os dados foram comparados entre pacientes de acordo com o IMC por ANOVA, Kruskal Wallis ou Qui-Quadrado. Para análise de sobrevivência, método de Kaplan Meier foi utilizado e, para ajustar variáveis confundidoras, usada regressão de Cox. Um modelo conjunto para dados longitudinais tempo-dependente foi utilizado, avaliando o impacto de variações longitudinais sobre a sobrevida. Resultados: Pacientes desnutridos (76,79 ± 7,53 anos), eram mais velhos (p < 0,0001) e apresentaram maior mortalidade (44,6%, p = 0,001). Diabetes mellitus foi mais prevalente em obesos (68%, p < 0,0001); níveis mais elevados de pressão arterial (p = 0,002) também foram mais frequentes em obesos e com sobrepeso. Conclusão: A variação positiva do IMC ao longo do tempo provou ser um fator de proteção, com uma diminuição de cerca de 1% no risco de morte por unidade de elevação do IMC.

Study of the incidence of dialysis in São Paulo, the largest Brazilian city

OBJECTIVES: Chronic kidney disease is a major public health problem worldwide. In Brazil, approximately 100,000 patients (January 2012) receive renal replacement therapy. Nevertheless, data on dialysis incidence in the Brazilian population are scarce. This study aims to analyze the incidence of patients starting dialysis therapy in São Paulo City, the largest Brazilian metropolis. METHOD: This cohort study analyzed data from 9,994 patients starting hemodialysis or peritoneal dialysis funded by the Brazilian Public Health System during a 5-year period (2007-2011). Patient data for this study (recorded as electronic files) were obtained from the São Paulo City's Dialysis Regulatory Bureau, which regulates the allocation of patients requiring dialytic therapy. RESULTS: The dialysis incidence rates were 178, 174, 170, 185 and 188 per million population for the years 2007, 2008, 2009, 2010 and 2011, respectively. The incidence rates increased with age. Hypertension and diabetes were the main etiologies diagnosed. Hemodialysis was the chosen dialysis modality in the majority of patients (92.6%), whereas the percentage of patients referred for peritoneal dialysis decreased from 10.1% to 5.5%. CONCLUSION: The incidence of patients starting renal replacement therapy from 2007-2011 in São Paulo was stable but higher than the projected incidence for the entire country. The authors emphasize the need for further studies of the incidence of dialysis in the Brazilian population and for the creation of a Brazilian registry of dialysis patients, which would be a valuable tool for developing healthcare policies and renal replacement therapy strategies. .

Body size and longitudinal body weight changes do not increase mortality in incident peritoneal dialysis patients of the Brazilian peritoneal dialysis multicenter study

OBJECTIVES: To determine the roles of body size and longitudinal body weight changes in the survival of incident peritoneal dialysis patients. PATIENTS AND METHODS: Patients (n = 1911) older than 18 years of age recruited from 114 dialysis centers (Dec/ 2004-Oct/2007) and participating in the Brazilian Peritoneal Dialysis Multicenter Cohort Study were included. Clinical and laboratory data were collected monthly (except if the patient received a transplant, recovered renal function, was transferred to hemodialysis, or died). RESULTS: Survival analyses were performed using Kaplan-Meier survival curves and Cox proportional hazards. Total follow-up was 34 months. The mean age was 59 years (54% female). The weight category percentages were as follows: underweight: 8%; normal: 51%; overweight: 29%; and obese 12%. The multivariate model showed a higher risk of death for a body mass index <18.5 kg/m², a neutral risk between 25 and 29.9 kg/m² and a protective effect for an index >30 kg/m². Patients were divided into five categories according to quintiles of body weight changes during the first year of dialysis: <-3.1%, -3.1 to+0.12%, +0.12 to <+3.1% (reference category), +3.1 to +7.1% and >+7.1%. Patients in the lowest quintile had significantly higher mortality, whereas no negative impact was observed in the other quintiles. CONCLUSION: These findings suggest that overweight/obesity and a positive body weight variation during the first year of peritoneal dialysis therapy do not increase mortality in incident dialysis patients in Brazil.

Fatores associados à qualidade de vida de pacientes incidentes em diálise peritoneal no Brasil (BRAZPD) / Factors associated with the quality of life of incident patients on PD in Brazil (BRAZPD)

INTRODUÇÃO: O número de pacientes em diálise peritoneal (DP) no Brasil é significativo, havendo maior prevalência de diabéticos e idosos neste grupo do que no grupo em hemodiálise. Esses dados apontam para um viés de seleção nessa população. Objetivo: Avaliar a qualidade de vida (QdV) na admissão de pacientes em diálise peritoneal no Brasil. MÉTODOS: Avaliados 6.198 pacientes participantes de um estudo de coorte prospectivo multicêntrico, utilizando-se os dados do BRAZPD. A avaliação da QdV foi realizada segundo o índice de Karnofsky (avaliação da QdV pelo profissional de saúde) e segundo o SF-36 (autoavaliação pelo paciente) em 1.624 pacientes incidentes. RESULTADOS: Entre os pacientes analisados, 40 por cento eram diabéticos e 47 por cento eram idosos (acima de 60 anos). Os pacientes apresentaram baixos escores de QdV em todos os aspectos do SF-36, sendo o domínio "aspectos físicos" o mais prejudicado. O domínio que apresentou melhor escore foi "aspecto social". Por outro lado, segundo o índice de Karnofsky, a maior parte dos pacientes possuía altos escores de QdV. Idosos e diabéticos apresentaram qualidade de vida inferior quando comparados aos não idosos e não diabéticos através da avaliação pelo SF-36 e pelo Karnofsky. CONCLUSÃO: Na avaliação geral pelo SF-36 observou-se redução da qualidade de vida. A avaliação pelo Karnofsky apresentou melhor performance comparado ao SF-36 na avaliação geral da qualidade de vida, sendo encontrados resultados semelhantes entre os dois instrumentos no que diz respeitos aos subgrupos avaliados, onde os grupos que apresentaram pior QdV foram pacientes diabéticos e idosos em ambas as avaliações.

INTRODUCTION: The number of patients on peritoneal dialysis (PD) in Brazil is significant, with a higher prevalence of diabetic and elderly individuals on PD than on hemodialysis. These data point to a selection bias in that population. OBJECTIVE: To assess the quality of life (QOL) of patients starting PD in Brazil. METHODS: The study assessed 6,198 patients participating in a multicenter prospective cohort study, using data from BRAZPD. The QOL was assessed by use of the Karnofsky index (QOL assessment by health professionals) and the SF-36 (patient's self-assessment) in 1,624 incident patients. RESULTS: Of the patients analyzed, 40 percent were diabetic and 47 percent were elderly (over the age of 60 years). Patients had low QOL scores in all the SF-36 domains, the "physical role" domain being the most affected and the "social functioning" domain having the best score. On the other hand, according to the Karnofsky index, most patients had high QOL scores. Elderly and diabetic patients had lower QOL as compared with non-elderly and non-diabetic by using both the SF-36 and Karnofsky index. CONCLUSION: The overall evaluation by use of the SF-36 showed a reduction in the QOL. The Karnofsky index showed a better QOL as compared with the SF-36 assessment, but similar results were found in the subgroups evaluated: the ederly and the diabetic patients had the worst QOL in both assessments.