Is C-reactive protein a useful predictor of outcome in peritoneal dialysis patients?

An elevated C-reactive protein (CRP) has recently been shown to be strongly predictive of mortality in hemodialysis patients. However, its predictive value in peritoneal dialysis (PD) patients has not been assessed. A cohort of 50 PD patients was followed prospectively for a 3-yr period, after initial determination of CRP. Patients with an elevated CRP (>6 mg/L; n = 29) had significantly reduced plasma prealbumin (0.36 +/- 0.02 versus 0.44 +/- 0.03 g/L; P: < 0.05), decreased total weekly creatinine clearance (C(Cr); 52.5 +/- 2.3 versus 63.1 +/- 3.2 L/1.73 m(2); P: < 0.01), and increased left ventricular thickness (1.24 +/- 0.05 versus 1.08 +/- 0.06 cm; P: < 0.05) at baseline compared with those who had a normal CRP (< or =6 mg/L; n = 21). Baseline CRP (log-transformed) correlated weakly with baseline Kt/V, C(Cr), and pre-albumin. With the use of a multivariate Cox's proportional hazards model to adjust for potential confounding factors, an elevated CRP was predictive of myocardial infarction (adjusted hazard ratio, 4.8; 95% confidence interval [CI], 1.0 to 23; P: = 0.048) and tended to be predictive of fatal myocardial infarction (adjusted hazard ratio, 6.0; 95% CI, 0.8 to 43; P: = 0.07). However, CRP was not significantly associated with all-cause mortality (adjusted hazard ratio, 2.1; 95% CI,0.8 to 5.4; P: = 0.15). In conclusion, CRP elevation occurs in a substantial proportion of PD patients and is independently predictive of future myocardial infarction. Such patients may warrant closer monitoring and attention to modifiable cardiovascular risk factors.     

Coronary artery bypass grafting in patients on maintenance dialysis: Is peritoneal dialysis a risk factor of operative mortality?

Background  Increasing numbers of patients on dialysis are undergoing coronary artery bypass grafting (CABG). We undertook this retrospective study to identify risk factors of operative mortality in dialysis patients who underwent CABG. Patients and methods  We performed retrospective analysis of 105 patients who were on dialysis for at least two months before surgery and who underwent CABG in Toronto General Hospital from 1997 to 2006. Using prospectively collected data from the Division of Cardiovascular Surgery Database of Toronto General Hospital, we collected data on comorbidities, procedures, modality change during hospitalization, and operative outcomes. Logistic regression was used to assess risk factors of operative mortality. Results  One hundred and five maintenance dialysis patients (40 PD and 65 HD) who met the inclusion criteria were studied. Overall in-hospital mortality was 7.6%. Atrial fibrillation and pneumonia occurred in 16.2 and 9.5%, respectively, of all dialysis patients. Among PD patients, rates of post-operative dialysate leak and peritonitis were 10 and 12.5%, respectively. Among HD patients, 4.6% experienced post-operative AV access thrombosis. Logistic regression showed older age (≥70 years) and peritoneal dialysis are independent risk factors of operative mortality. Conclusion  In this retrospective study, older patients on PD had higher operative mortality than HD patients. These findings suggest extra care should be taken when CABG is considered for PD patients over 70 years old. In this study we could not identify the reason(s) for the high mortality of elderly peritoneal dialysis patients undergoing CABG.     

Preservation of residual renal function in peritoneal dialysis patients: still a dream?

The results of the randomized trial by Fan et al. suggest that 'biocompatible' peritoneal dialysis solutions have no major advantage over standard solutions in peritoneal dialysis patients in relation to residual renal function (RRF) and technique survival. The possible effect of more biocompatible peritoneal dialysis solutions on RRF should be tested in patients starting peritoneal dialysis programs with relatively well-preserved RRF. When RRF is already very poor, it is very unlikely that a more biocompatible peritoneal dialysis solution can preserve highly damaged and sclerotic kidneys.     

Is oxidative stress an issue in peritoneal dialysis?

During the last two decades, oxidative stress (OS) has emerged as a novel risk factor for a variety of adverse events, including atherosclerosis and mortality in chronic kidney disease (CKD) patients. Increased OS occurs even in early stages of the disease, progresses with deterioration of renal function and is further aggravated by hemodialysis (HD), due to the bioincompatibility of the method. Compared to HD, peritoneal dialysis (PD) is a more biocompatible dialysis modality, characterized by a significantly reduced, but still high, OS status. The culprit for OS in PD is mainly the composition of PD solutions (low pH, lactate buffer, increased osmolarity and high glucose concentration). After heat sterilization of PD solutions, formation of glucose degradation products (GDPs) and advanced glycation end‐products (AGEs) trigger inflammation and enhance OS. Chronic exposure of the peritoneum to this toxic, hyperglycemic environment leads to OS‐derived morphologic damage of peritoneal cells, loss of ultrafiltration capacity and decreased technique survival. Moreover, OS is linked with peritonitis, loss of residual renal function, inflammation, atherosclerosis, cardiovascular (CV) disease, and increased mortality. To ameliorate OS status in PD, a multitargeted approach is necessary that includes use of neutral pH, low GDP, low lactate and iso‐ismolar PD solutions, strict glycemic control, optimal volume management and, probably supplementation with antioxidants, N‐acetylcysteine being the most promising among them.     

Residual renal function and volume status in peritoneal dialysis patients: a conflict of interest?

Fluid status and volume homeostasis are extremely important in patients with CKD stage 5, as cardiovascular disease, including congestive heart failure and hypertension, is one of the leading causes of death in this patient group. Many epidemiologic studies have meanwhile indicated that indeed preservation of volume control is a key component of adequate peritoneal dialysis. On the other hand, residual renal function is also an important and powerful predictor of outcome in peritoneal dialysis (PD) patients. This has led some authors to advocate a state of "slight fluid overload" to preserve residual renal function. This paper seeks to highlight the idea that probably the reason residual renal function is so important, is that it is elementary in the maintenance of a good fluid balance, and that that reasoning should not be inverted. In addition, we will indicate that volume overload in itself might lead to a faster decline of residual renal function. The paper will also point out some important practice points to avoid deterioration of residual renal function in PD patients, such as strict sodium diet and good glycemic control, that are also key to maintaining a good fluid balance.     

Assessment of protein nitrogen appearance in Chinese peritoneal dialysis patients-which method to use?

OBJECTIVE: We compared the Bergstrom's and Randerson's formula for PNA determination, and compared the normalization of PNA by ideal body weight (IBW) and standard body weight (SBW) as estimated by the Watson's formula. METHODS. We studied 208 Chinese PD patients. Two 24-h dialysate and urine collections were performed six months apart. Protein nitrogen appearance was determined by the Randerson's formula (PNA-Rand) and Bergstrom's formula (PNA-Berg), the latter used as the gold standard. PNA-Berg was normalized with IBW and SBW, denoted as NPNA-IBW and NPNA-Watson respectively. The change of PNA over six months, denoted as APNA-Rand and APNA-Berg, were calculated. The results were compared by the Bland and Altman's method. RESULTS: At zero month, the average PNA-Berg was 61.8 +/- 14.8 g/day, and the average PNA-Rand was 58.1 +/- 14.5 g/day. The value of PNA-Rand was consistently lower than the corresponding PNA-Berg. The bias of PNA-Rand was -3.7g/day. The limits of agreement were -9.2 to +1.8 g/day. When NPNA-Watson was compared to NPNA-IBW, the bias of NPNA-Watson, using NPNA-IBW as gold standard, was 0.01 g/kg/day; the limits of agreement were -0.22 to +0.23 g/kg/day. The difference between NPNA-Watson and NPNA-IBW correlated with the body mass index (r = -0.820, p < 0.001) and body weight (r = -0.834, r < 0.001). After six month, there was a significant reduction in urine protein loss. However, total protein loss was only slightly reduced (7.3 +/- 3.0 to 6.9 +/- 2.8 g/day, p = 0.029). The correlation between APNA-Berg and APNA-Rand remained excellent (r = 0.983, p < 0.001). The bias of APNA-Rand was +0.3 g/day; the limits of agreement were -4.7 to +5.2 g/day. CONCLUSION: Ideal body weight that is validated for specific ethnic group, rather than the Watson's formula, should be used for normalization of PNA. Although the Randerson's formula under-estimates PNA when compared to the Bergstrom's formula, it is a reliable method for serial PNA monitoring because dialysate protein loss is stable in most patients.     

Is hyperbilirubinaemia in appendicitis a better predictor of perforation than C-reactive protein? — a prospective study

Purpose  

To compare the performance for the prediction of perforated appendicitis of total bilirubin versus C-reactive protein (CRP), white blood cell count, the time period of symptoms’ evolution, and systemic inflammatory response syndrome (SIRS).     

Does loss of residual renal function lead to malnutrition in peritoneal dialysis patients?

OBJECTIVES: It is usually believed that loss of residual renal function is associated with anorexia and the development of malnutrition. We conducted a retrospective study in our center to evaluate the effect of declining residual renal function on patients' nutritional status. METHODS: All incident uremic patients (n = 46) who began peritoneal dialysis from January 1, 2003 June 1, 2003 in our center were closely followed for 1 year with focus on maintaining strict volume control with time on dialysis. Patient's residual renal function (RRF) was assessed by the average renal urea and creatinine clearances. Those patients who had more than 50% decrease in GFR were selected for the present analysis. Serum albumin (ALB), dietary protein intake (DPI) and subjective global assessment (SGA) were closely followed. RESULTS: There were 16 patients (9 males and 7 females) included in the present analysis, among whom 31.3% were diabetics. Patients' GFR declined significantly (RRF were 4.32 +/- 2.69, 2.99 +/- 2.21 and 1.24 +/- 0.99 ml/min for Months 1, 6 and 12, respectively, p < 0.05), along with a significant decline in urine volume (985.62 +/- 543.29, 698.13 +/- 463.59 and 425.63 +/- 320.52 ml/d for Months 1, 6 and 12, respectively, p < 0.01). Although weekly peritoneal Kt/V did not increase significantly, peritoneal ultrafiltration increased significantly during this period (428.75 +/- 408.96, 534.38 +/- 296.39, 844.38 +/- 440.35 ml for Months 1, 6 and 12, respectively, p < 0.05). Serum ALB increased significantly (32.34 +/- 5.07, 34.74 +/- 4.89 and 36.21 +/- 3.98 g/l for Months 1, 6 and 12, respectively, p < 0.01). DPI also increased significantly. The prevalence of malnutrition (by SGA) decreased from 62.5% at the start of dialysis to 18.8% at the end of this study (p < 0.05). CONCLUSIONS: Our study suggests that rapid decline of residual renal function in PD patients does not necessarily lead to decreased dietary protein intake and deteriorated nutritional status. Focus on incremental peritoneal fluid removal along with the decline in residual renal function and, thus, maintaining volume control may be one of the critical reasons for the success.     

Does low peritoneal glucose load protect from the development of left ventricular hypertrophy in peritoneal dialysis patients?

Background

Left ventricular hypertrophy (LVH) is a major predictor of the development of cardiovascular events that is considered the main cause of morbidity and mortality in peritoneal dialysis (PD) patients. This study aimed to evaluate retrospectively the impact of low peritoneal glucose load on left ventricular mass (LVM) in PD patients.

Methods

36 patients who were on continuous ambulatory PD for at least a period of 2 years enrolled in the study. Of them, 23 patients received only glucose-based solutions (GBS) [high peritoneal glucose load group (HPGL group)] from the start of PD, and 13 patients received AAS in combination with GBS when their serum albumin decreased to levels <3.5 g/dl [low peritoneal glucose load group (LPGL group)]. AAS was substituted with 1.36 % GBS when serum albumin rose to ≥3.5 g/dl and restarted when serum albumin fell to <3.5 g/dl. Medical history, physical findings, echocardiographic, laboratory and hydration status data from the first month of PD and after 24 months, were obtained from each patient’s medical records.

Results

Mean LVM index (LVMI) increased in both groups (p ≤ 0.010). The increment in mean LVMI was higher in HPGL group compared to LPGL group (p = 0.006). At 24 months: peritoneal glucose load index (PGLI), fluid overload, mean arterial pressure (MAP), HbA1c and hsCRP were higher in HPGL group (p ≤ 0.010), while 24 h ultrafiltration, weekly Kt/V, serum albumin levels and RRF were higher in LPGL group (p ≤ 0.025). The increment (Δ between the values of each parameter from the start of PD and after 24 months) in PGLI, fluid overload, MAP, HbA1c and hsCRP values were higher in HPGL group (p < 0.001).

Conclusions

Low peritoneal glucose load may be associated with a protective effect from the development of LVH in PD patients.

     

Hepatitis C inflection in dialysis patients: a link to poor clinical outcome?

Among the 350,000 maintenance dialysis patients in the USA, the mortality rate is high (20–23% per year) as is the prevalence of hepatitis C virus (HCV) infection (5–15%). An additional same number of dialysis patients in the USA may be infected with HCV but have undetectable HCV antibodies. Almost half of all deaths in dialysis patients, including HCV-infected patients, are due to cardiovascular disease. Since over two-thirds of dialysis patients die within 5 years of initiating dialysis and because markers of malnutrition–inflammation complex syndrome (MICS), rather than traditional cardiovascular risk factors, are among the strongest predictors of early death in these patients, the impact of HCV infection on nutritional status and inflammation may be a main cause of poor survival in this population. Based on data from our cross-sectional and limited longitudinal studies, we hypothesize that HCV infection confounds the association between MICS and clinical outcomes in dialysis patients and, by doing so, leads to higher short-term cardiovascular events and death. Understanding the natural history of HCV and its association with inflammation, nutrition and outcomes in dialysis patients may lead to testing more effective anti-HCV management strategies in this and other similar patient populations, providing benefits not only for HCV infection but the detrimental consequences associated with this infection. In this article, we review the link between the HCV infection and mortality in dialysis patients and compare HCV antibody to molecular methods to detect HCV infection in these individuals. Funding source: Supported by a Young Investigator Award from the National Kidney Foundation; the National Institute of Diabetes, Digestive and Kidney Disease grant # DK61162; and a research grant from DaVita (for KKZ); and the National Institute of Allergy and Infectious Diseases grant # AI01831 (for LGM and HD41224 (for ESD)).     

Is successful treatment of depression in dialysis patients an achievable goal?

Depression is undisputedly common among individuals with End‐Stage Kidney Failure and associated with adverse outcomes. It is well recognized that effective treatments for depression are needed within routine dialysis care. But, are we any closer to successfully treating depression in dialysis patients? We consider this question here with respect to two common treatments, antidepressant medication and cognitive behavioural therapy (CBT). Currently, there are limited data from randomized placebo‐controlled trials regarding the acceptability and efficacy of antidepressants. CBT trials appear to show more consistent treatment effects, albeit the feasibility of routine delivery remains unknown. No studies in dialysis patients has evaluated the combined effects of CBT with antidepressants. There is a need to consider pragmatic depression treatment trials in dialysis patients in order to increase study recruitment in order to have more reliable data from which to evaluate the evidence base. Furthermore, we need to understand why treatments work, and for whom do they work? Lastly, addressing issues surrounding treatment acceptability and implementation as part of regular care remain as key challenges that require attention if we are to improve the mental health of individuals on dialysis.