Effect of Serum Albumin Changes on Mortality in Patients with Peritoneal Dialysis: A Joint Modeling Approach and Personalized Dynamic Risk Predictions.

Peritoneal dialysis (PD) is a frequently used and growing therapy for end-stage renal diseases (ESRD). Survival analysis of PD patients is an ongoing research topic in the field of nephrology. Several biochemical parameters (e.g., serum albumin, creatinine, and blood urea nitrogen) are measured repeatedly in the follow-up period; however, baseline or averaged values are primarily associated with mortality. Although this strategy is not incorrect, it leads to information loss, resulting in erroneous conclusions and biased estimates. This retrospective study used the trajectory of common renal function indexes in PD patients and mainly investigated the association between serum albumin change and mortality. Furthermore, we considered patient-specific variability in serum albumin change and obtained personalized dynamic risk predictions for selected patients at different follow-up thresholds to investigate the effect of serum albumin trajectories on patient-specific mortality. We included 417 patients from the Erciyes University Nephrology Department whose data were retrospectively collected using medical records. A joint modeling approach for longitudinal and survival data was used to investigate the relationship between serum albumin trajectory and mortality of PD patients. Results showed that averaged serum albumin levels were not associated with mortality. However, serum albumin change was significantly and inversely associated with mortality (HR: 2.43, 95% CI: 1.48 to 4.16). Risk of death was positively associated with peritonitis rate, hemodialysis history, and the total number of comorbid and renal diseases with hazard ratios 1.74, 3.21, and 1.41. There was also significant variability between patients. The personalized risk predictions showed that overall survival estimates were not representative for all patients. Using the patient-specific trajectories provided better survival predictions within the follow-up period as more data become available in serum albumin levels. In conclusion, using the trajectory of risk predictors via an appropriate statistical method provided better predictive accuracy and prevented biased findings. We also showed that personalized risk predictions were much informative than overall estimations in the presence of significant patient variability. Furthermore, personalized estimations may play an essential role in monitoring and managing patients during the follow-up period.

Effect of Change in Fluid Status Evaluated by Bioimpedance Techniques on Body Composition in Hemodialysis Patients.

OBJECTIVE: This prospective study uses calf bioimpedance spectroscopy (cBIS) to guide the attainment of dry weight (DWcBIS) in chronic hemodialysis (HD) patients. The primary aim of this study was to evaluate whether body composition is altered when fluid status is reduced to DWcBIS. METHODS: Target post-HD weight was gradually reduced from baseline (BL) until DWcBIS was achieved. DWcBIS was defined as the presence of both flattening of the curve of extracellular resistance and the attainment calf normalized resistivity in the normal range during the dialysis treatment. Extracellular volume (ECV), intracellular volume, and total body water (TBW) were measured using whole body BIS (Hydra 4200). Fluid overload, lean body mass, and fat mass were calculated according to a body composition model. RESULTS: Seventy-three patients enrolled and 60 completed the study (55 ± 13 years, 49% male). Twenty-eight patients (25% diabetes) achieved DWcBIS, whereas 32 patients (47% diabetes) did not. Number of treatment measurements were 16 ± 10 and 12 ± 13 studies per patient in the DWcBIS and non-DWcBIS groups, respectively. Although significant decreases in body weight and ECV were observed, lean body mass and FM did not differ significantly in both groups from BL to the end of study. ECV, ECV/TBW, and fluid overload were higher in the non-DWcBIS than in the DWcBIS group both at BL and at the end of study. Ratios of intradialytic changes in calf normalized resistivity, ECV, and ECV/TBW to ultrafiltration volume were significantly lower in diabetic than in non-diabetic patients. CONCLUSIONS: This study shows that decreasing fluid status by gradual reduction of post-HD weight in both DWcBIS and Non-DWcBIS groups did not affect body composition significantly over a period of about 4 weeks.

The course of peritoneal membrane transport in patients on long-term peritoneal dialysis: what is it affected by?

BACKGROUND: The aim of this study was to investigate the course of peritoneal membrane transport in patients on long-term peritoneal dialysis (PD) and to identify possible factors affecting its course. METHODS: This study included 101 patients on long-term PD. The median duration of PD was 106 (range, 80-189) months. All patients had least 2 peritoneal equilibration tests (PET). The patients were divided to 3 groups according to the change between the peritoneal transport types at the first PET and the last PET. In the first group, peritoneal transport type stayed stable. It tended to increase in second group whereas there was a trend toward to decrease in the third group. RESULTS: Mean dialysate/plasma creatinine was significantly increased with time. It was 0.64±0.1 and 0.74±0.1 at the first and the last PET, respectively (P<0.001). Number of patients in low and low-average groups was significantly decreased whereas number of patients in high average and high groups was significantly increased with time (P<0.001). There was significant difference among 3 groups with regard to glucose exposure (P=0.018). It was significantly higher in second group compared to other two groups. There was no significant difference among 3 groups with regard to other demographic, clinical, and biochemical parameters (P>0.05). CONCLUSION: Peritoneal membrane permeability was increased in patients on long-term PD with time and the increase in the permeability was affected by glucose exposure.

Comparison of bioimpedance techniques to detect changes in fluid status in hemodialysis patients.

UNLABELLED: Bioimpedance (BI) is maturing as a clinical technique for assessing fluid volume status. The aim of this study was to compare the sensitivity of four BI methods to detect changes in fluid status in hemodialysis patients. METHODS: Forty-five patients were studied twice in the same week, i.e. once after the long and short interdialytic intervals, respectively. The four BI methods used were: (a) calf normalized resistivity (CNR) at a 5-kHz frequency, (b) whole-body multifrequency BI spectroscopy (MF-BIS) to estimate the normal hydration weight (NHWWBM), (c) whole-body MF-BIS to estimate the ratio of extracellular volume to total body water (wECV/wTBW), and (d) whole-body single-frequency (50 kHz) BI analysis to compute the ratio of ECV (sfECV) to TBW (sfTBW). RESULTS: The relationship (slope of the regressive line) between relative changes (%) in the above mentioned four BI parameters and differences in weight (kg) was most pronounced with CNR (5.2 ± 1.6%/kg), followed by wECV/wTBW (1.7 ± 0.7%/kg) and NHWWBM (0.73 ± 0.2%/kg). Changes in sfECV/sfTBW and differences in weight were not correlated. CONCLUSIONS: CNR is more sensitive than whole-body BIS for detecting differences in fluid status.

Early systolic blood pressure changes in incident hemodialysis patients are associated with mortality in the first year.

BACKGROUND: In incident hemodialysis (HD) patients, the relationship between early systolic blood pressure (SBP) dynamics and mortality is unknown. METHODS: Baseline SBP levels were stratified into 5 categories ranging from <120 and ≥180 mm Hg. Early pre-HD SBP change was defined as the slope of pre-HD SBP from week 1 to 12 and categorized in quartiles (Q1, lowest slope). SBP slopes were computed for each patient by simple linear regression. RESULTS: In 3,446 incident HD patients (42% females, 44% black, age 62 ± 15 years), the median pre-HD SBP slope was -1.7 (Q1) to +2.3 (Q4) mm Hg/week. In an adjusted multivariate Cox regression analysis, patients with declining SBP (slope Q1) had higher mortality compared to patients with increasing pre-HD SBP (slope Q4) at 12 months (hazard ratio 2.01, 95% confidence interval 1.35-3.01). In addition, patients with baseline pre-HD SBP <120 mm Hg showed higher mortality compared to the reference group (SBP ≥180 mm Hg) at 12 months (hazard ratio 1.89, 95% confidence interval 1.03-3.45). CONCLUSION: Baseline pre-HD SBP and early SBP dynamics are associated with mortality in the first year of dialysis. Patients who had low (pre-HD SBP <120 mm Hg) or declining SBP had the highest mortality rates. Particular attention is warranted in incident HD patients with low or declining SBP.

Impact of arterial stiffness on adverse cardiovascular outcomes and mortality in peritoneal dialysis patients.

BACKGROUND: Cardiovascular (CV) disease is a major cause of morbidity and mortality in patients with end-stage renal disease. In recent years, arterial stiffness has taken on great importance in the pathophysiology of CV diseases. The independent predictive value of arterial stiffness for CV events and for all-cause and CV mortality has been demonstrated in the general population and in hemodialysis patients. Our aim in this study was to determine the relationship of arterial stiffness with mortality and fatal and nonfatal CV events in peritoneal dialysis (PD) patients. METHODS: In this prospective observational cohort study with 2 years of follow-up, we studied a cohort of 156 PD patients with a mean follow-up of 19.2 ± 6.4 months. At baseline, echocardiography and standard clinical and biochemical analyses were performed in all patients and in 28 healthy subjects. Aortic stiffness index beta (ASIß, a surrogate marker of arterial stiffness) was calculated as follows: ASIß = ln (systolic blood pressure / diastolic blood pressure) / [(systolic diameter ­ diastolic diameter) / diastolic diameter]. RESULTS: During the follow-up period, 25 of the patients (16.0%) died, and 10 of those deaths had CV causes. Nonfatal CV events occurred in 15 patients. The median ASIß was greater in PD patients than in control subjects (4.2 vs. 3.5; interquartile range: 3.2 - 5.5 vs. 2.5 - 4.8; p = 0.028]. In the fully adjusted multivariate Cox regression analysis (co-variates: age, sex, albumin, hemoglobin, diabetes mellitus, comorbid CV disease, left ventricular mass index, residual glomerular filtration rate, dialysate-to-plasma ratio of creatinine, Kt/V urea, left ventricular ejection fraction, duration of dialysis, smoking), ASIß independently predicted fatal and nonfatal CV events (hazard ratio: 1.239; 95% confidence interval: 1.103 to 1.392), but not all-cause mortality. CONCLUSIONS: Our results provide the first direct evidence that arterial stiffness is an independent risk predictor of adverse CV outcome in PD patients.

Determination of fluid status in haemodialysis patients with whole body and calf bioimpedance techniques.

AIM: The aim of this study was to demonstrate the ability of widely used bioimpedance techniques to assess dry weight (DW) and to predict a state of normal hydration in haemodialysis patients whose post-dialysis weight had been gradually reduced from baseline in successive treatments over time. METHODS: Calf bioimpedance spectroscopy (cBIS) was employed to determine DW (DW(cBIS) ) as defined by flattening of an intradialytic continuously measured resistance curve and by normalized resistivity (nRho) being in the gender-specific normal range. The wECV/TBW ratio was determined by 'classical' wrist-to-ankle whole body bioimpedance spectroscopy (wBIS); in addition, a novel whole body model (WBM) based on wBIS was used to predict normal hydration weight (NHW(WBM) ). RESULTS: Twenty-one haemodialysis patients were studied; 11 ± 6 measurements were performed per patient. Nine patients reached DW(cBIS) (DW(cBIS) group), while 12 patients remained fluid-overloaded (non-DW(cBIS) group). Change in wECV as measured by wBIS accounted for 46 ± 23% in DW(cBIS) group, which was higher than in non-DW(cBIS) group (33 ± 48%, P < 0.05) of actual weight loss at the end of study. In both groups the wECV/TBW ratio did not change significantly between baseline and study end. Mean predicted NHW(WBM) at baseline was 3.55 ± 1.6 kg higher than DW(cBIS) . The difference in DW(cBIS) and NHW(WBM) was 1.97 ± 1.0 kg at study end. CONCLUSION: WBM could be useful to predict a target range of normal hydration weight particularly for patients with substantial fluid overload. The cBIS provides an accurate reference for the estimation of DW so that combined use of cBIS and WBM is promising and warrants further studies.

Extrapulmonary tuberculosis in a hemodialysis patient with unusual clinical presentation.

The incidence of active tuberculosis in patients undergoing maintenance dialysis for a long time is considerably higher than that in general population. A 39-year-old male treated by hemodialysis three times a week for six months was admitted to the hospital with a painless mass palpable under his right areola. X-ray examination of chest showed a hyperintense lesion. Computed tomography revealed a cystic mass in the superior segment of inferior lobe near the thoracic vertebrae. Needle aspiration of the lesion revealed granulomas and acid-resistant bacteria. Anti-tuberculous therapy was therefore initiated. After eight months the patient was admitted back with paraplegia. Magnetic resonance imaging (MRI) revealed that the lesion defined by computed tomography (CT) was extending to the spinal duct and compressing the spinal cord. A tissue biopsy was performed and granulomas were identified. Mycobacterium tuberculosis grew in the culture. This case suggests that in areas with a high incidence of tuberculosis renal patients in a high-risk group should be examined periodically to exclude insidious infection and reduce morbidity and mortality.