Pasqual Barretti

High volume peritoneal dialysis vs daily hemodialysis: A randomized, controlled trial in patients with acute kidney injury

There is no consensus in the literature on the best renal replacement therapy (RRT) in acute kidney injury (AKI), with both hemodialysis (HD) and peritoneal dialysis (PD) being used as AKI therapy. However, there are concerns about the inadequacy of PD as well as about the intermittency of HD complicated by hemodynamic instability. Recently, continuous replacement renal therapy (CRRT) have become the most commonly used dialysis method for AKI around the world. A prospective randomized controlled trial was performed to compare the effect of high volume peritoneal dialysis (HVPD) with daily hemodialysis (DHD) on AKI patient survival. A total of 120 patients with acute tubular necrosis (ATN) were assigned to HVPD or DHD in a tertiary-care university hospital. The primary end points were hospital survival rate and renal function recovery, with metabolic control as the secondary end point. Sixty patients were treated with HVPD and 60 with DHD. The HVPD and DHD groups were similar for age (64.2+/-19.8 and 62.5+/-21.2 years), gender (male: 72 and 66%), sepsis (42 and 47%), hemodynamic instability (61 and 63%), severity of AKI (Acute Tubular Necrosis-Index Specific Score (ATN-ISS): 0.68+/-0.2 and 0.66+/-0.2), Acute Physiology, Age, and Chronic Health Evaluation Score (APACHE II) (26.9+/-8.9 and 24.1+/-8.2), pre-dialysis BUN (116.4+/-33.6 and 112.6+/-36.8 mg per 100 ml), and creatinine (5.8+/-1.9 and 5.9+/-1.4 mg per 100 ml). Weekly delivered Kt/V was 3.6+/-0.6 in HVPD and 4.7+/-0.6 in DHD (P<0.01). Metabolic control, mortality rate (58 and 53%), and renal function recovery (28 and 26%) were similar in both groups, whereas HVPD was associated with a significantly shorter time to the recovery of renal function. In conclusion, HVPD and DHD can be considered as alternative forms of RRT in AKI.

Geographic and Educational Factors and Risk of the First Peritonitis Episode in Brazilian Peritoneal Dialysis Study (BRAZPD) Patients

BACKGROUND AND OBJECTIVES Peritonitis remains as the most frequent cause of peritoneal dialysis (PD) failure, impairing patients outcome. No large multicenter study has addressed socioeconomic, educational, and geographic issues as peritonitis risk factors in countries with a large geographic area and diverse socioeconomic conditions, such as Brazil. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS Incident PD patients recruited from 114 dialysis centers and reporting to BRAZPD, a multicenter observational study, from December 2004 through October 2007 were included. Clinical, dialysis-related, demographic, and socioeconomic variables were analyzed. Patients were followed up until their first peritonitis. Cox proportional model was used to determine independent factors associated with peritonitis. RESULTS In a cumulative follow-up of 2032 patients during 22.026 patient-months, 474 (23.3%) presented a first peritonitis episode. In contrast to earlier findings, PD modality, previous hemodialysis, diabetes, gender, age, and family income were not risk predictors. Factors independently associated with increased hazard risk were lower educational level, non-white race, region where patients live, shorter distance from dialysis center, and lower number of patients per center. CONCLUSIONS Educational level and geographic factors as well as race and center size are associated with risk for the first peritonitis, independent of socioeconomic status, PD modality, and comorbidities.

Peritoneal Dialysis-Related Peritonitis Due to Staphylococcus aureus: A Single-Center Experience over 15 Years

Peritonitis caused by Staphylococcus aureus is a serious complication of peritoneal dialysis (PD), which is associated with poor outcome and high PD failure rates. We reviewed the records of 62 S. aureus peritonitis episodes that occurred between 1996 and 2010 in the dialysis unit of a single university hospital and evaluated the host and bacterial factors influencing peritonitis outcome. Peritonitis incidence was calculated for three subsequent 5-year periods and compared using a Poisson regression model. The production of biofilm, enzymes, and toxins was evaluated. Oxacillin resistance was evaluated based on minimum inhibitory concentration and presence of the mecA gene. Logistic regression was used for the analysis of demographic, clinical, and microbiological factors influencing peritonitis outcome. Resolution and death rates were compared with 117 contemporary coagulase-negative staphylococcus (CoNS) episodes. The incidence of S. aureus peritonitis declined significantly over time from 0.13 in 1996–2000 to 0.04 episodes/patient/year in 2006–2010 (p = 0.03). The oxacillin resistance rate was 11.3%. Toxin and enzyme production was expressive, except for enterotoxin D. Biofilm production was positive in 88.7% of strains. The presence of the mecA gene was associated with a higher frequency of fever and abdominal pain. The logistic regression model showed that diabetes mellitus (p = 0.009) and β-hemolysin production (p = 0.006) were independent predictors of non-resolution of infection. The probability of resolution was higher among patients aged 41 to 60 years than among those >60 years (p = 0.02). A trend to higher death rate was observed for S. aureus episodes (9.7%) compared to CoNS episodes (2.5%), (p = 0.08), whereas resolution rates were similar. Despite the decline in incidence, S. aureus peritonitis remains a serious complication of PD that is associated with a high death rate. The outcome of this infection is negatively influenced by host factors such as age and diabetes mellitus. In addition, β-hemolysin production is predictive of non-resolution of infection, suggesting a pathogenic role of this factor in PD-related S. aureus peritonitis.

Acute Renal Failure: Clinical Outcome and Causes of Death

Acute renal failure (ARF) is a frequent complication in hospitalized patients and is strongly related to increase in mortality. In order to analyze the clinical outcome and the prognostic factors in hospital-acquired ARF, a prospective study was performed. Data from 200 patients with established ARF during the period of January 1987 through July 1990 were collected. The incidence of ARF was 4.9/1000 admissions. Renal ischemia (50%) and nephrotoxic drugs (21%) were the main etiologic factors. The histologic study done in 43 patients showed: acute tubular necrosis (53%), tubular hydropic degeneration (16%), glomerulopathies (16%), and other lesions (15%). Dialysis therapy was performed in 101 patients. The mortality rate was 46.5% and the most important causes of death were: sepsis (38%), respiratory failure (19%), and multiple organ failure (11%). Higher mortality was observed in oliguric patients (62.9%) than nonoliguric (34.5%) (p < 0.05) and in ischemic renal failure (56.7%) when compared to nephrotoxic renal failure (14.7%) (p < 0.05). As primary cause of death was not associated to the acute renal failure, we conclude that acute renal failure is an important marker of the gravity of the underlying disease and not the cause of death.

Peritoneal Dialysis in Acute Renal Failure

The definition of adequate dialysis in acute renal failure (ARF) is complex and involves the time of referral to dialysis, dose, and dialytic method. Nephrologist experience with a specific procedure and the availability of different dialysis modalities play an important role in these choices. There is no consensus in literature on the best method or ideal dialysis dose in ARF. Peritoneal dialysis (PD) is used less and less in ARF patients, and is being replaced by continuous venovenous therapies. However, it should not be discarded as a worthless therapeutic option for ARF patients. PD offers several advantages over hemodialysis, such as its technical simplicity, excellent cardiovascular tolerance, absence of an extracorporeal circuit, lack of bleeding risk, and low risk of hydro-electrolyte imbalance. PD also has some limitations, though: it needs an intact peritoneal cavity, carries risks of peritoneal infection and protein losses, and has an overall lower effectiveness. Because daily solute clearance is lower with PD than with daily HD, there have been concerns that PD cannot control uremia in ARF patients. Controversies exist concerning its use in patients with severe hypercatabolism; in these cases, daily hemodialysis or continuous venovenous therapy have been preferred. There is little literature on PD in ARF patients, and what exists does not address fundamental parameters such as adequate quantification of dialysis and patient catabolism. Given these limitations, there is a pressing need to re-evaluate the adequacy of PD in ARF using accepted standards. Therefore, new studies should be undertaken to resolve these problems.

The role of virulence factors in the outcome of staphylococcal peritonitis in CAPD patients

BackgroundPeritonitis continues to be the most frequent cause of peritoneal dialysis (PD) failure, with an important impact on patient mortality. Gram-positive cocci such as Staphylococcus epidermidis, other coagulase-negative staphylococci (CoNS), and Staphylococcus aureus are the most frequent etiological agents of PD-associated peritonitis worldwide. The objective of the present study was to compare peritonitis caused by S. aureus and CoNS and to evaluate the factors influencing outcome.MethodsRecords of 86 new episodes of staphylococcal peritonitis that occurred between 1996 and 2000 in the Dialysis unit of a single university hospital were studied (35 due to S. aureus, 24 to S. epidermidis and 27 to other CoNS). The production of slime, lipase, lecithinase, nuclease (DNAse), thermonuclease (TNAse), α- and β-hemolysin, enterotoxins (SEA, SEB, SEC, SED) and toxic shock syndrome toxin-1 (TSST-1) was studied in S. aureus and CoNS. Antimicrobial susceptibility was evaluated based on the minimal inhibitory concentration determined by the E-test. Outcome predictors were evaluated by two logistic regression models.ResultsThe oxacillin susceptibility rate was 85.7% for S. aureus, 41.6% for S. epidermidis, and 51.8% for other CoNS (p = 0.001). Production of toxins and enzymes, except for enterotoxin A and α-hemolysin, was associated with S. aureus episodes (p < 0.001), whereas slime production was positive in 23.5% of CoNS and 8.6% of S. aureus strains (p = 0.0047). The first model did not include enzymes and toxins due to their association with S. aureus. The odds of resolution were 9.5 times higher for S. epidermidis than for S. aureus (p = 0.02) episodes, and were similar for S. epidermidis and other CoNS (p = 0.8). The resolution odds were 68 times higher for non-slime producers (p = 0.001) and were not influenced by oxacillin resistance among vancomycin-treated cases (p = 0.89). In the second model, the resolution rate was similar for S. aureus and S. epidermidis (p = 0.70), and slime (p = 0.001) and α-hemolysin (p = 0.04) production were independent predictors of non-resolution.ConclusionBacterial species and virulence factors rather than antibiotic resistance influence the outcome of staphylococcal peritonitis.

Influence of protein intake and muscle mass on survival in chronic dialysis patients

Introduction: Some studies suggest that high body mass index (BMI) confers survival advantage in dialysis patients, but BMI does not differentiate muscle from fat mass, and the survival advantage conferred by its increase seems to be limited to patients with high muscle mass. Thus, discriminating body components when evaluating nutritional status and survival is highly important. This study evaluated the influence of nutritional parameters on survival in patients on chronic dialysis. Subjects and methods: Anthropometry, bioimpedance, biochemistry, and dietary recall were used to investigate the influence of nutritional parameters on survival in 79 prevalent patients on chronic dialysis. Results: Protein intake <1.2 g/kg/day and creatinine <9.7 mg/dL were independent predictors of mortality in all patients. Regarding dialysis method, protein intake <1.2 g/kg/day was predictive of mortality among hemodialysis patients, and percent standard mid-arm muscle circumference <80% was identified as a risk factor among peritoneal dialysis patients. Conclusion: Higher muscle mass, possibly favored by a higher protein intake, conferred survival advantage in dialysis patients.

Low Serum Potassium Levels Increase the Infectious-Caused Mortality in Peritoneal Dialysis Patients: A Propensity-Matched Score Study

Background and Objectives Hypokalemia has been consistently associated with high mortality rate in peritoneal dialysis. However, studies investigating if hypokalemia is acting as a surrogate marker of comorbidities or has a direct effect in the risk for mortality have not been studied. Thus, the aim of this study was to analyze the effect of hypokalemia on overall and cause-specific mortality. Design, Setting, Participants and Measurements This is an analysis of BRAZPD II, a nationwide prospective cohort study. All patients on PD for longer than 90 days with measured serum potassium levels were used to verify the association of hypokalemia with overall and cause-specific mortality using a propensity match score to reduce selection bias. In addition, competing risks were also taken into account for the analysis of cause-specific mortality. Results There was a U-shaped relationship between time-averaged serum potassium and all-cause mortality of PD patients. Cardiovascular disease was the main cause of death in the normokalemic group with 133 events (41.8%) followed by PD-non related infections, n=105 (33.0%). Hypokalemia was associated with a 49% increased risk for CV mortality after adjustments for covariates and the presence of competing risks (SHR 1.49; CI95% 1.01-2.21). In contrast, in the group of patients with K <3.5mEq/L, PD-non related infections were the main cause of death with 43 events (44.3%) followed by cardiovascular disease (n=36; 37.1%). For PD-non related infections the SHR was 2.19 (CI95% 1.52-3.14) while for peritonitis was SHR 1.09 (CI95% 0.47-2.49). Conclusions Hypokalemia had a significant impact on overall, cardiovascular and infectious mortality even after adjustments for competing risks. The causative nature of this association suggested by our study raises the need for intervention studies looking at the effect of potassium supplementation on clinical outcomes of PD patients.

Impact of patient training patterns on peritonitis rates in a large national cohort study

BACKGROUND Ideal training methods that could ensure best peritoneal dialysis (PD) outcome have not been defined in previous reports. The aim of the present study was to evaluate the impact of training characteristics on peritonitis rates in a large Brazilian cohort. METHODS Incident patients with valid data on training recruited in the Brazilian Peritoneal Dialysis Multicenter Study (BRAZPD II) from January 2008 to January 2011 were included. Peritonitis was diagnosed according to International Society for Peritoneal Dialysis guidelines; incidence rate of peritonitis (episodes/patient-months) and time to the first peritonitis were used as end points. RESULTS Two thousand two hundred and forty-three adult patients were included in the analysis: 59 ± 16 years old, 51.8% female, 64.7% with ≤4 years of education. The median training time was 15 h (IQI 10-20 h). Patients were followed for a median of 11.2 months (range 3-36.5). The overall peritonitis rate was 0.29 per year at risk (1 episode/41 patient-months). The mean number of hours of training per day was 1.8 ± 2.4. Less than 1 h of training/day was associated with higher incidence rate when compared with the intervals of 1-2 h/day (P = 0.03) and >2 h/day (P = 0.02). Patients who received a cumulative training of >15 h had significantly lower incidence of peritonitis compared with <15 h (0.26 per year at risk versus 0.32 per year at risk, P = 0.01). The presence of a caregiver and the number of people trained were not significantly associated with peritonitis incidence rate. Training in the immediate 10 days after implantation of the catheter was associated with the highest peritonitis rate (0.32 per year), compared with training prior to catheter implantation (0.28 per year) or >10 days after implantation (0.23 per year). More experienced centers had a lower risk for the first peritonitis (P = 0.003). CONCLUSIONS This is the first study to analyze the association between training characteristics and outcomes in a large cohort of PD patients. Low training time (particularly <15 h), smaller center size and the timing of training in relation to catheter implantation were associated with a higher incidence of peritonitis. These results support the recommendation of a minimum amount of training hours to reduce peritonitis incidence regardless of the number of hours trained per day.

Characterization of the BRAZPD II cohort and description of trends in peritoneal dialysis outcome across time periods.

Observational studies from different regions of the world provide valuable information in patient selection, clinical practice, and their relationship to patient and technique outcome. The present study is the first large cohort providing patient characteristics, clinical practice, patterns and their relationship to outcomes in Latin America. The objective of the present study was to characterize the cohort and to describe the main determinants of patient and technique survival, including trends over time of peritoneal dialysis (PD) initiation and treatment. This was a nationwide cohort study in which all incident adult patients on PD from 122 centers were studied. Patient demographics, socioeconomic and laboratory values were followed from December 2004 to January 2011 and, for comparison purposes, divided into 3 groups according to the year of starting PD: 2005/06, 2007/08 and 2009/10. Patient survival and technique failure (TF) were analyzed using the competing risk model of Fine and Gray. All patients active at the end of follow-up were treated as censored. In contrast, all patients who dropped the study for any reason different from the primary event of interest were treated as competing risk. Significance was set to a p level of 0.05. A total of 9,905 patients comprised the adult database, 7,007 were incident and 5,707 remained at least 90 days in PD. The main cause of dropout was death (54%) and of TF was peritonitis (63%). Technique survival at 1, 2, 3, 4, and 5 years was 91%, 84%, 77%, 68%, and 58%, respectively. There was no change in TF during the study period but 3 independent risk factors were identified: lower center experience, lower age, and automated PD (APD) as initial therapy. Cardiovascular disease (36%) was the main cause of death and the overall patient survival was 85%, 74%, 64%, 54%, and 48% at 1, 2, 3, 4, and 5 years, respectively. Patient survival improved along all study periods: compared to 2005/2006, patients starting at 2007/2008 had a relative risk reduction (SHR) of 0.83 (95% confidence interval [CI] 0.72 - 0.95); and starting in 2009/2010 of 0.69 (95% CI 0.57 - 0.83). The independent risk factors for mortality were diabetes, age > 65 years, previous hemodialysis, starting PD modality, white race, low body mass index (BMI), low educational level, center experience, length of pre-dialysis care, and the year of starting PD. We observed an improvement in patient survival along the years. This finding was sustained even after correction for several confounders and using a competing risk approach. On the other hand, no changes in technique survival were found.