Bioimpedance spectroscopy: Is a picture worth a thousand words?

Volume status can be difficult to assess in dialysis patients. Peripheral edema, elevated venous pressure, lung crackles, and hypertension are taught as signs of fluid overload, but sensitivity and specificity are poor. Bioimpedance technology has evolved from early single frequency to multifrequency machines which apply spectroscopic analysis (BIS), modeling data to physics-based mixture theory. Bioimpedance plots can aid the evaluation of hydration status and body composition. The challenge remains how to use this information to manage dialysis populations, particularly as interventions to improve over hydration, sarcopenia, and adiposity are not without side effects. It is therefore of no surprise that validation studies for BIS use in peritoneal dialysis patients are limited, and results from clinical trials are inconsistent and conflicting. Despite these limitations, BIS has clinical utility with potential to accurately evaluate small changes in body tissue components. This article explains the information a BIS plot ("picture") can provide and how it can contribute to the overall clinical assessment of a patient. However, it remains the role of the clinician to integrate information and devise treatment strategies to optimize competing patient risks, fluid and nutrition status, effects of high glucose PD fluids on membrane function, and quality of life issues.

Relationship between sodium removal, hydration and outcomes in peritoneal dialysis patients.

BACKGROUND: Fluid overload (FO) in peritoneal dialysis (PD) patients is associated with mortality. We explore if low daily sodium removal is an independent risk factor for mortality. We examined severely FO PD patients established for >1 year in expectation that PD prescription would have been optimized for solute clearance and ultrafiltration. We also wish to determine the relationship between kt/v and sodium removal. METHODS: Retrospective analysis of 231 PD patients with FO ≥2.0 L and compared with 218 PD patients who were euvolaemic throughout their PD treatment. Patients were followed up until death censored for transplantation. RESULTS: Mean daily sodium removal in overhydrated patients was only 75 mmoles (=1.7 g). CAPD usage was more common in patients with the highest sodium removal. Achievement of UK guidelines for solute clearance and daily fluid removal were not independent predictors of mortality. Markers of sarcopenia (low serum albumin and high CRP) were associated with increased mortality, but these parameters were not independent predictors in a model that included functional assessment (Karnofsky score). Daily sodium removal was not predictive of mortality but the imprecision of clinically used sodium assay should be noted. The correlation between Na and kt/v is statistically significant but R2 was weak at .07. CONCLUSION: While diabetic males were more likely to become overhydrated, these factors did not increase mortality further. Traditional targets of 'dialysis adequacy' did not predict survival. Kt/v is not a good indicator of sodium removal which can be surprisingly low. Measuring sodium clearance may help clinicians optimize PD modality (CAPD vs. APD).

Peritoneal dialysis in patients with failed kidney transplant: Single centre experience.

AIM: To determine if patients with failing kidney transplants who opt to have peritoneal dialysis (PD) have poor short-term PD technique survival and increased rates of peritonitis. METHODS: We performed a retrospective analysis comparing 50 consecutive patients starting PD after a failed kidney transplant to 93 incident patients starting PD (matching for age, gender, diabetes causing renal failure, ethnicity and year of starting PD). RESULTS: The mean follow-up period was 26 months. PD technique survival was lower for the post-transplant cohort. However, this did not appear to be related to PD peritonitis risk; infection rate was lower in the post-transplant group albeit not statistically significant (1 in 23.6 patient months vs 1 in 22.5 patient months). There were no differences in the proportion of Gram positive: Gran negative: Culture Negative infections. The only fungal peritonitis occurred in a Control patient. Results of baseline Peritoneal Equilibration Tests were not different; D/Pcr was 0.69 for post-TP versus 0.64 for Control (P = ns), and net UF was 250 mL for post-TP versus 310 mL for Control (P = ns). PET results after 12 months were also similar. CONCLUSION: Our study found a small but significantly higher rate of PD technique failure in the post-transplant cohort, but this did not appear to be related to peritonitis rates or peritoneal membrane function. Further studies are required to explore reasons for PD technique failure in patients who have had kidney transplant, but our study supports the use of PD in selected patient from this cohort.

Could metformin be used in patients with diabetes and advanced chronic kidney disease?

Diabetes is an important cause of end stage renal failure worldwide. As renal impairment progresses, managing hyperglycaemia can prove increasingly challenging, as many medications are contra-indicated in moderate to severe renal impairment. Whilst evidence for tight glycaemic control reducing progression to renal failure in patients with established renal disease is limited, poor glycaemic control is not desirable, and is likely to lead to progressive complications. Metformin is a first-line therapy in patients with Type 2 diabetes, as it appears to be effective in reducing diabetes related end points and mortality in overweight patients. Cessation of metformin in patients with progressive renal disease may not only lead to deterioration in glucose control, but also to loss of protection from cardiovascular disease in a cohort of patients at particularly high risk. We advocate the need for further study to determine the role of metformin in patients with severe renal disease (chronic kidney disease stage 4-5), as well as patients on dialysis, or pre-/peri-renal transplantation. We explore possible roles of metformin in these circumstances, and suggest potential key areas for further study.

Addressing the burden of dialysis around the world: A summary of the roundtable discussion on dialysis economics at the First International Congress of Chinese Nephrologists 2015.

To address the issue of heavy dialysis burden due to the rising prevalence of end-stage renal disease around the world, a roundtable discussion on the sustainability of managing dialysis burden around the world was held in Hong Kong during the First International Congress of Chinese Nephrologists in December 2015. The roundtable discussion was attended by experts from Hong Kong, China, Canada, England, Malaysia, Singapore, Taiwan and United States. Potential solutions to cope with the heavy burden on dialysis include the prevention and retardation of the progression of CKD; wider use of home-based dialysis therapy, particularly PD; promotion of kidney transplantation; and the use of renal palliative care service.

Renal Association Clinical Practice Guideline on peritoneal dialysis in adults and children.

These guidelines cover all aspects of the care of patients who are treated with peritoneal dialysis. This includes equipment and resources, preparation for peritoneal dialysis, and adequacy of dialysis (both in terms of removing waste products and fluid), preventing and treating infections. There is also a section on diagnosis and treatment of encapsulating peritoneal sclerosis, a rare but serious complication of peritoneal dialysis where fibrotic (scar) tissue forms around the intestine. The guidelines include recommendations for infants and children, for whom peritoneal dialysis is recommended over haemodialysis.Immediately after the introduction there is a statement of all the recommendations. These recommendations are written in a language that we think should be understandable by many patients, relatives, carers and other interested people. Consequently we have not reworded or restated them in this lay summary. They are graded 1 or 2 depending on the strength of the recommendation by the authors, and A-D depending on the quality of the evidence that the recommendation is based on.

Use of Continuous Glucose Monitoring in Patients with Diabetes Mellitus on Peritoneal Dialysis: Correlation with Glycated Hemoglobin and Detection of High Incidence of Unaware Hypoglycemia.

INTRODUCTION: Glycated hemoglobin is used to assess diabetic control although its accuracy in dialysis has been questioned. How does it compare to the Continuous Glucose Monitoring System (CGMS) in peritoneal dialysis (PD) patients? METHODS: We conducted a retrospective analysis of 60 insulin-treated diabetic patients on PD. We determined the mean interstitial glucose concentration and the proportion of patients with hypoglycemia (<4 mmol/l) or hyperglycemia (>11 mmol/l). RESULTS: The correlation between HbA1c and glucose was 0.48, p < 0.0001. Three of 15 patients with HbA1c >75 mmol/mol experienced significant hypoglycemia (14-144 min per day). The patients with frequent episodes of hypoglycemia could not be differentiated from those with frequent hyperglycemia by demographics or PD prescription. CONCLUSION: HbA1c and average glucose levels measured by the CGMS are only weakly correlated. On its own, HbA1c as an indicator of glycemic control in patients with diabetes on PD appears inadequate. We suggest that the CGMS technology should be more widely adopted.

Hydration status measured by BCM: A potential modifiable risk factor for peritonitis in patients on peritoneal dialysis.

AIM: Peritoneal dialysis peritonitis and fluid overhydration (OH) are frequent problems in peritoneal dialysis. The latter can cause gut wall oedema or be associated with malnutrition. Both may lead to increased peritonitis risk. We wished to determine if OH is an independent risk factor for peritonitis (caused by enteric organisms). METHODS: Retrospectively study of patients with >2 bioimpedance assessments (Body Composition Monitor). We compared peritonitis rates of patients with above or below the median time-averaged hydration parameter (OH/extracellular water, OH/ECW). Multivariate analysis was performed to determine independent risk factors for peritonitis by enteric organism. RESULTS: We studied 580 patients. Peritonitis was experienced by 28% patients (followed up for an average of 17 months). The overall peritonitis rate was 1:34 patient months. Patients with low OH/ECW values had significantly lower rates of peritonitis from enteric organisms than overhydrated patients (incident rate ratio 1.53, 95% confidence interval 1.38-1.70, P < 0.001). Hydration remained an independent predictor of peritonitis from enteric organisms when multivariate model included demographic parameters (odds ratio for a 1% increment of OH/ECW was 1.05; 95% confidence interval 1.01-1.10, P < 0.02). However, including biochemical parameters of malnutrition reduced the predictive power of overhydration. CONCLUSION: We found an association between overhydration and increased rates of peritonitis. While this may partly be due to the high co-morbidity of patients (advanced age and diabetes), on multivariate analysis, only inclusion of nutritional parameters reduced this association. It remains to be determined if overhydration will prove to be a modifiable risk factor for peritonitis or whether malnutrition will prove to be more important.

Practical aspects of volume control in chronic kidney disease using whole body bioimpedance.

BACKGROUND: Fluid status is an independent predictor of mortality in dialysis patients. Current methods of fluid assessment have several limitations. SUMMARY: An ideal method should be cheap, portable, easy to perform without extensive training, reproducible and determines patients' excess or deficit of total body water. Bioimpedance analysis (BIA) fulfils many of these criteria and can give additional information on fat and lean tissue composition. The accuracy and precision of BIA has been shown to be equivalent to the 'gold standard' direct estimation techniques. KEY MESSAGES: Although there remains some concern about its validity in dialysis patients, fluid overload determined by BIA has been shown to predict mortality. BIA-guided fluid management appears superior to conventional fluid management in achieving clinically important outcomes such as reduction in blood pressure, left ventricular mass index, and arterial stiffness. Accurate setting of dry weight might also help preserve residual renal function by limiting episodes of dehydration. Nevertheless, as with all new technologies, there are issues that still need to be resolved. This will be achieved only with larger prospective interventional studies to explore its specific roles in dialysis cohorts.

Comparing lung ultrasound with bioimpedance spectroscopy for evaluating hydration in peritoneal dialysis patients.

BACKGROUND: Bioimpedance spectroscopy (BIS), ultrasound lung comets (ULC) and serum biomarkers (N-terminal pro-brain natriuretic peptide, NT-proBNP) have all been used to assist clinicians to determine hydration status in dialysis patients. METHODS: We performed simultaneous BIS, ULC and NT-proBNP measurements in 27 peritoneal dialysis patients to determine the concordance of the three methods. RESULTS: Patients with evidence of increasing lung congestion (as determined by ultrasound) were more likely to be diabetic, have systolic hypertension and have higher NT-proBNP (r = 0.65, P < 0.0005). Although there was a trend for patients with high ULC to be overhydrated as determined by BIS, this did not reach statistical significance. Moreover, the correlation between BIS and NT-proBNP (though statistically significant at r = 0.47, P < 0.02) appeared to be weaker. CONCLUSION: BIS and ULC may be complementary, providing different information, whereas BIS may be more specific to hydration. ULC and NT-proBNP may indicate left ventricular failure coexisting with overhydration.

Can Bioimpedance Measurements of Lean and Fat Tissue Mass Replace Subjective Global Assessments in Peritoneal Dialysis Patients?

OBJECTIVE: Malnutrition and protein energy wasting (PEW) determined by Subjective Global Assessment (SGA) is associated with increased mortality. There is an inverse relationship between body mass and overhydration in dialysis patients. Is the predictive accuracy of SGA (for death) independent of hydration status? Can bioimpedance spectroscopy analysis of lean tissue index (LTI) and fat tissue index (FTI) accurately identify dialysis patients with protein energy wasting and increased mortality? METHODS: We report an observational study of 455 peritoneal dialysis (PD) patients. RESULTS: We found that 96 patients (21%) were malnourished (SGA score between 1 and 5), and 192 (42%) had LTI values below 10th centile (age, gender adjusted). FTI was significantly lower in the SGA-defined malnourished cohort. By contrast, there was an inverse relationship between LTI and FTI. Malnourished (by SGA) patients were significantly more overhydrated (P < .0001), but SGA remained highly predictive of survival in multivariate analysis that included hydration status (hazard ratio: 3.12, 95% confidence interval 1.86-5.23, P < .0001). Obesity (patients with the highest 20% FTI) predicted survival (hazard ratio of death was 0.47, 95% confidence interval 0.16-0.85, P < .02) on univariate but not multivariate analysis. CONCLUSIONS: We have confirmed that SGA is an accurate predictor of mortality in PD patients, and its predictive value is independent of the hydration status. Predictive power of SGA was not affected when LTI and FTI were included in multivariate analysis. Patients with low LTI were different from patients with low SGA (associated with high FTI). Sensitivity and specificity of Body Composition Monitor to diagnose patients with low SGA readings were poor (area under the curve for receiver operator characteristics analysis 0.66). The phenomenon of reverse epidemiology (high FTI predicting a survival advantage) was found in our PD cohort.

Clinical significance of multi-frequency bioimpedance spectroscopy in peritoneal dialysis patients: independent predictor of patient survival.

BACKGROUND: It is becoming increasingly evident that the accurate assessment of hydration status is critical to care of a dialysis patient. Using the Body Composition Monitor, different parameters (overhydration (OH), extra-cellular water/total body water (ECW/TBW) or OH/ECW) have been proposed to indicate hydration status. We wished to determine which parameter (if any) was most predictive of all-cause mortality, and if this was independent of nutritional indices. METHODS: We performed a single-centre retrospective analysis of prospectively collected data of all peritoneal dialysis (PD) patients between 1 January 2008 and 30 March 2012. Record review was undertaken to establish patient survival, clinical and demographic data. Follow-up was continued even after PD technique failure (transfer to haemodialysis) and transplantation. RESULTS: The study included 529 patients. OH index (OH and OH/ECW) was the independent predictor of mortality in multi-variate analysis. ECW/TBW as a continuous variable was not associated with increased risk of death. In contrast, patients that were severely overhydrated (highest 33%) had hazard ratios (HRs) that were statistically significant irrespective of the parameter used to define hydration. Using OH, severely overhydrated patients had an HR of 1.83 [95% confidence interval (CI) 1.19-2.82, P < 0.01], OH/ECW: 2.09 (95% CI 1.36-3.20, P < 0.001) and ECW/TBW: 2.05 (95% CI 1.31-3.22, P < 0.005). CONCLUSIONS: Our results also indicated that there was no influence of body mass index (BMI) on the hydration parameter OH/ECW. OH/ECW remained an independent predictor of mortality when the BMI and lean tissue index were included in multivariate model. However, it remains to be determined if correcting the OH status of a patient will lead to improvement in mortality.

Increased peritoneal dialysis exit site infections using topical antiseptic polyhexamethylene biguanide compared to mupirocin: results of a safety interim analysis of an open-label prospective randomized study.

Prophylactic mupirocin for peritoneal catheter exit sites reduces exit site infection (ESI) risk but engenders antibiotic resistance. We present early interim safety analysis of an open-label randomized study comparing polyhexamethylene biguanide (PHMB) and mupirocin. A total of 106 patients randomized to 53 in each group were followed up for a mean of 12.68 months per patient. On safety analysis, the PHMB group had a significantly greater ESI rate than the mupirocin group (odds ratio [OR], 0.26; 95% confidence interval [CI], 0.09 to 0.80), leading to discontinuation of the trial.

Managing diabetes in dialysis patients.

Burgeoning levels of diabetes are a major concern for dialysis services, as diabetes is now the most common cause of end-stage renal disease in most developed nations. With the rapid rise in diabetes prevalence in developing countries, the burden of end stage renal failure due to diabetes is also expected to rise in such countries. Diabetic patients on dialysis have a high burden of morbidity and mortality, particularly from cardiovascular disease, and a higher societal and economic cost compared to non-diabetic subjects on dialysis. Tight glycaemic and blood pressure control in diabetic patients has an important impact in reducing risk of progression to end stage renal disease. The evidence for improving glycaemic control in patients on dialysis having an impact on mortality or morbidity is sparse. Indeed, many factors make improving glycaemic control in patients on dialysis very challenging, including therapeutic difficulties with hypoglycaemic agents, monitoring difficulties, dialysis strategies that exacerbate hyperglycaemia or hypoglycaemia, and possibly a degree of therapeutic nihilism or inertia on the part of clinical diabetologists and nephrologists. Standard drug therapy for hyperglycaemia (eg, metformin) is clearly not possible in patients on dialysis. Thus, sulphonylureas and insulin have been the mainstay of treatment. Newer therapies for hyperglycaemia, such as gliptins and glucagon-like peptide-1 analogues have become available, but until recently, renal failure has precluded their use. Newer gliptins, however, are now licensed for use in 'severe renal failure', although they have yet to be trialled in dialysis patients. Diabetic patients on dialysis have special needs, as they have a much greater burden of complications (cardiac, retinal and foot). They may be best managed in a multidisciplinary diabetic-renal clinic setting, using the skills of diabetologists, nephrologists, clinical nurse specialists in nephrology and diabetes, along with dietitians and podiatrists.

Long-term follow-up of patients randomized to biocompatible or conventional peritoneal dialysis solutions show no difference in peritonitis or technique survival.

Peritonitis remains a common clinical problem for patients on peritoneal dialysis (PD). There are, however, retrospective studies with historical controls that suggest that biocompatible PD solutions may reduce the rates of peritonitis. We conducted a randomized controlled study comparing the use of biocompatible and conventional solutions, accumulating over 7000 patient-months experience. We included peritonitis episodes from patients who discontinued PD during the follow-up period. The study was powered to detect a reduction in the peritonitis rate of over half in the 267 randomized patients in demographically similar groups. There were no intergroup differences in PD technique survival irrespective of whether the outcome was censored for death. Peritonitis-free survival was 26.7 months using conventional compared to 23.1 months using biocompatible PD solutions. The peritonitis rates were also not statistically different when measured in patient-months. Thus, despite the finding of non-randomized studies suggesting benefits of the biocompatible PD solutions, we could not detect any clinically significant advantages in terms of technique survival or peritonitis. Although our study is the largest randomized study comparing different PD solutions to date, we do not exclude the possibility that our results are a consequence of the lack of statistical power. Meta-analysis of randomized control trials in this field is essential.

Comparing automated peritoneal dialysis with continuous ambulatory peritoneal dialysis: survival and quality of life differences?

BACKGROUND: There is a wide disparity in the use of automated peritoneal dialysis (APD) or continuous ambulatory peritoneal dialysis (CAPD) in the UK. This may be due to a perceived quality of life and technique survival advantage with APD, although evidence is lacking. METHODS: We conducted a single-centre retrospective study of incident end-stage renal disease initiating APD and CAPD with data collected prospectively over 5 years. PD modality was based on patient preference. Health status was assessed using SF-36 questionnaires at initial and 1-year follow-up appointments. RESULTS: Three hundred and seventy-two patients were included: 194 patients chose APD, and 178 patients chose CAPD. CAPD patients were generally older and more dependent than APD patients. Univariate analysis for technique survival was inferior for CAPD (relative risk for failure 1.46, 95% CI 1.08-1.97). But on multivariate analysis when comorbidity was added into the model, PD modality was no longer a significant predictor of technique survival. There was no difference in decline in residual renal function. Baseline CAPD patients had worse health status (HS); mean (SEM) physical and social composite scores were 32.3 (0.9) vs 36.5 (0.9) and 33.3 (1.2) vs 40.3 (1.2). After 1 year, HS scores for CAPD and APD patients were similar, but the improvement in HS scores correlated with baseline scores (PD modality was not an independent predictor of the change in HS). CONCLUSIONS: This study did not show any advantages of APD over CAPD in terms of technique survival or HS. There is no evidence to support physician bias towards one PD modality, and both should be available to allow patient choice.

Estimation of residual glomerular filtration rate in peritoneal dialysis patients using cystatin C: comparison with 51Cr-EDTA clearance.

BACKGROUND: Measuring glomerular filtration rate (GFR) is an important assessment in peritoneal dialysis patients. In clinical practice, it is commonly measured by calculating the mean of the urinary clearance of urea and creatinine (GFR(UrCl)) but this process is time consuming and unreliable. We wished to compare several estimates of GFR including residual GFR estimated from cystatin C (GFR(CysC)) using a published equation (Hoek), GFR(UrCl) and (51)Cr-ethylenediaminetetraacetic acid (EDTA) clearance, in peritoneal dialysis patients. METHODS: GFR(CysC), GFR(UrCl) and (51)Cr-EDTA clearance were measured in 28 patients undergoing peritoneal dialysis in a single dialysis unit. RESULTS: GFR(CysC) was related to GFR(UrCl) (Spearman's rank correlation coefficient r(s) = 0.44; P = 0.0185) and to (51)Cr-EDTA clearance (r(s) = 0.48; P = 0.0099). GFR(CysC) values were significantly (P = 0.0077) lower than (51)Cr-EDTA clearance results (mean bias -19.7%). However, GFR(CysC) did not differ significantly (P > 0.05) from GFR(UrCl). CONCLUSIONS: GFR(CysC) is related to GFR(UrCl) but has a significant negative bias against (51)Cr-EDTA. Given the known limitations of (51)Cr-EDTA in estimating GFR in renal failure, this study provides additional validation suggesting that cystatin C-estimated rGFR (GFR(CysC)) gives a reasonable estimation of GFR without the clinical problems associated with 24 h urine collections.

Accelerated decline of GFR in diabetic nephropathy predicted by interferon release assay to tuberculosis antigens.

BACKGROUND: The QuantiFERON® test (QFT) is a diagnostic tool for active and latent tuberculosis (TB) infections. High rates of positivity to QuantiFERON® have been demonstrated in patients with chronic kidney disease (CKD) and diabetic patients. We performed a pilot study to investigate if QFT positivity in diabetic CKD patients predicted the rate of renal function decline. METHODS: QFT was performed in 38 diabetic patients with CKD 4-5 not on dialysis. The rate of decline in estimated glomerular filtration rate (eGFR) was calculated. RESULTS: 18/38 patients had a positive QFT. Patients with a positive QFT had a steeper decline in eGFR, compared with patients with a negative QFT. Ethnicity (a marker of risk of previous TB exposure), urine protein/creatinine ratio, use of ACE inhibitors/angiotensin II receptor blockers and statins, serum C-reactive protein, vitamin D levels, HbA1c concentration and presenting GFR did not differ significantly. CONCLUSIONS: The finding in this small cohort needs to be replicated in a larger study because our study is susceptible to both type I and type II statistical error. We found that QFT positivity was associated with a more rapid rate of decline in GFR, but this association may be coincidental (with the difference in decline attributed to differences in the blood pressure or proteinuria of the two groups). Moreover, an association does not necessarily mean causality, although it would be interesting to speculate if we are identifying patients with latent TB who have an active interstitial nephritis. Another intriguing possibility is that this assay identifies patients with an immunological phenotype that predisposes to eGFR loss.

Do oral aluminium phosphate binders cause accumulation of aluminium to toxic levels?

BACKGROUND: Aluminium (Al) toxicity was frequent in the 1980s in patients ingesting Al containing phosphate binders (Alucaps) whilst having HD using water potentially contaminated with Al. The aim of this study was to determine the risk of Al toxicity in HD patients receiving Alucaps but never exposed to contaminated dialysate water. METHODS: HD patients only treated with Reverse Osmosis(RO) treated dialysis water with either current or past exposure to Alucaps were given standardised DFO tests. Post-DFO serum Al level > 3.0 µmol/L was defined to indicate toxic loads based on previous bone biopsy studies. RESULTS: 39 patients (34 anuric) were studied. Mean dose of Alucap was 3.5 capsules/d over 23.0 months. Pre-DFO Al levels were > 1.0 µmol/L in only 2 patients and none were > 3.0 µmol/L. No patients had a post DFO Al levels > 3.0 µmol/L. There were no correlations between the serum Al concentrations (pre-, post- or the incremental rise after DFO administration) and the total amount of Al ingested.No patients had unexplained EPO resistance or biochemical evidence of adynamic bone. CONCLUSIONS: Although this is a small study, oral aluminium exposure was considerable. Yet no patients undergoing HD with RO treated water had evidence of Al toxicity despite doses equivalent to 3.5 capsules of Alucap for 2 years. The relationship between the DFO-Al results and the total amount of Al ingested was weak (R² = 0.07) and not statistically significant. In an era of financial prudence, and in view of the recognised risk of excess calcium loading in dialysis patients, perhaps we should re-evaluate the risk of using Al-based phosphate binders in HD patients who remain uric.

Polymerase chain reaction/electrospray ionization-mass spectrometry (PCR/ESI-MS) is not suitable for rapid bacterial identification in peritoneal dialysis effluent.

BACKGROUND: Peritoneal dialysis (PD)-related peritonitis is a serious complication of PD, but routine microbiological culture is slow and could not identify the organism in 15% cases. We examine the accuracy of polymerase chain reaction/electrospray ionization-mass spectrometry (PCR/ESI-MS), a PCR-based method developed for the direct detection of bacteria in blood, for rapid identification of microorganisms from PD effluent. METHODS: We recruited 73 consecutive patients with PD-related peritonitis. Dialysis effluent was collected for routine bacterial culture, PCR/ESI-MS, and bacterial DNA quantification before initiation of antibiotic therapy. RESULTS: By digital PCR with universal bacterial primers, bacterial DNA was detectable in all PD effluent specimens. For the entire cohort, taking standard bacterial culture as the gold standard, the PCR/ESI-MS assay correctly identified 34.3% of the causative organisms, failed to identify any organism in 52.1% cases, and identified a different organism in 8.2% cases. For the 14 episodes of peritonitis that were culture negative by conventional bacterial culture, the PCR/ESI-MS assay identified an organism in only four cases. The detection rate of the IRIDICA BAC BSI assay was not affected by the use of biocompatible PD solution or concomitant exit-site infection. CONCLUSIONS: The PCR/ESI-MS assay could not identify the causative organism in over 50% of the PD effluent samples in patients with PD-related peritonitis and should be not used for such purpose. The reason for the poor performance needs further investigation.