Diálise peritoneal no idoso: análise de uma coorte multicêntrica brasileira

Abstract

Introduction: Since old age is a risk factor for chronic kidney disease (CKD), we are experiencing today higher and progressive incidence of elderly patients on renal replacement therapy (RRT). As there is no Brazilian studies on peritoneal dialysis (PD) in elderly patients, we consider necessary to understand topics in this population. The objectives of this study are to describe a cohort of peritoneal dialysis elderly patients; evaluate risk factors associated with patient survival; assess the impact of blood pressure, body mass index and anemia on survival. Patients and Methods: A multicenter prospective cohort study was designed from December 2004 to October 2007. Evaluated 102 centers with more than ten patients on peritoneal dialysis and who were using Baxter systems. The data filled by nurses and physicians, were divided into sociodemographic, clinical and laboratory. Patients were followed until death, kidney transplantation, hemodialysis (HD) transfer, recovery of renal function or loss of follow-up. Elderly patients were considered over 60 years of age and all PD incidents patients incidents that have completed 90 days of therapy were included. We performed a descriptive analysis of data, expressed as mean ± standard deviation, median, or percentage, as the variables were categorical or numerical (normal or not). Normality was assessed using the Kolmogorov-Smirnov test. To compare the groups regarding initial therapy, first PD vs. HD first, we used the chi-square or Kruskal Wallis. A similar analysis was used to compare patients on automated peritoneal dialysis (APD) vs continuous ambulatory peritoneal dialysis (CAPD). Data were compared between the patients divided according to body mass index (BMI) or blood pressure levels by ANOVA, Kruskal Wallis or the chi square. Competitive risk analysis and time-dependent Cox were performed, considering the dialysis modality (DPA vs. APD) as dependent variables, since HR is not proportional throughout therapy time. To analyze survival, we used the Kaplan Meier curve and the log rank, when required. We assess the risk factors associated with major clinical outcomes or death using the Cox regression model. In this analysis, those transferred from the clinic, transfer to HD, with recovery of renal function or transplant were censored. The association of blood pressure behavior, anemia and BMI with clinical outcomes was done using analysis models that consider these same variables as modified in time (time dependent regression analysis). A joint model for longitudinal data and time dependent was conducted, assessing impact of a longitudinal variable displays on survival. We adopted whenever possible the 95% confidence interval (CI) and the calculation of odds ratio. Software used: SPSS 15.0 and STATA 13. Results: 1) Mean age 74.5 ± 6.8 years in APD, 74.6 ± 6.7 in 9 CAPD, 50.8% female in APD, 54.4% in CAPD. Comorbidities: diabetes (52.3% in APD and 47% in CAPD) and left ventricular hypertrophy (36.3% in APD and 46.1% in CAPD) whereas 93.6% presented Davies score ≥ 2. In Cox time dependent analysis, HR showed that beyond 18 month, APD modality revealed lower risk of mortality (HR=0.25, CI=0.073-0.86) when compared with CAPD. 2) Malnourished patients (76.79 ± 7.53 years) were older (p = <0.0001) with higher percentage of death (44.6%, p = 0.001); diabetes showed higher prevalence in obese patients (68%, p <0.0001); higher blood pressure levels (p = 0.002) were present in obese and overweight patients. APD was a protective factor beyond 18 months; 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; increase of systolic blood pressure is protective, reaching 40% decrease in risk of death for a slope of a unit; the mean initial hemoglobin (Hb) is protective with approximately 12% decrease in risk of death for each Hb unit. Conclusions: This study showed that APD is better than CAPD from the 18th month of therapy, and that the increase in BMI and systolic BP throughout therapy proved protective, as well as hemoglobin on admission.