Predictors and Outcomes of Transfers from Peritoneal Dialysis to Hemodialysis

♦ Introduction:

Peritoneal dialysis (PD) patients are commonly required to transfer to hemodialysis (HD), however the literature describing the outcomes of such transfers is limited. The aim of our study was to describe the predictors of these transfers and their outcomes according to vascular access at the time of transfer.

♦ Methods:

A retrospective cohort study using registry data of all adult patients commencing PD as their initial renal replacement therapy in Australia or New Zealand between 2004 – 2010 was performed. Follow-up was until 31 December 2010. Logistic regression models were constructed to determine possible predictors of transfer within both 6 and 12 months of PD commencement. Cox analysis and competing risks regression were used to determine the predictors of survival and transplantation post-transfer.

♦ Results:

The analysis included 4,781 incident PD patients, of whom 1,699 transferred to HD during the study period. Logistic models did not identify any clinically useful predictors of transfer within 6 or 12 months (c-statistics 0.54 and 0.55 respectively). 67% of patients commenced HD with a central venous catheter (CVC). CVC use at transfer was associated with increased mortality (hazard ratio 1.37, 95% confidence interval (CI) 1.11 – 1.68, p = 0.003) and a borderline significant reduction in the incidence of transplantation (subhazard ratio 0.76, 95% CI 0.58 – 1.00, p = 0.05).

♦ Conclusions:

It is difficult to predict the transfer to HD for incident PD patients. PD patients who commence HD with a CVC have a higher risk of mortality and a lower likelihood of undergoing renal transplantation.     

Development and Testing of Self-Management Scale for PD Patients

♦ Objectives:

To develop and evaluate the self-management scale for peritoneal dialysis (PD) patients.

♦ Methods:

The item pool was formulated based on literature reviews and in-depth interviews. An initial scale containing five factors and 44 items was constructed through two rounds of Delphi expert consultation and a preliminary test. A total of 313 PD patients from the Jiangsu-Zhejiang-Shanghai area were surveyed to test the reliability and validity of the scale.

♦ Results:

Five factors, namely solution bag replacement, troubleshooting during operation, diet management, complication monitoring, emotion management and return to social life, were extracted by exploratory factor analysis: the 28 items could explain 64.567% of the total variance; the content validity index was 0.963; the Cronbach’s α coefficient and split-half coefficient were 0.926 and 0.960 respectively; and test-retest reliability was 0.937.

♦ Conclusion:

The scale has been proved to be a reliable and valid tool which allows PD nurses to evaluate the self-management ability of PD patients. The evaluation outcomes can serve as a basis for individualized nursing plans and interventions so as to provide highly effective nursing care.     

Blood pressure and cardiovascular disease risk in the Veterans Affairs Diabetes Trial

OBJECTIVE

Blood pressure ranges associated with cardiovascular disease (CVD) events in advanced type 2 diabetes are not clear. Our objective was to determine whether baseline and follow-up (On-Study) systolic blood pressure (SBP), diastolic blood pressure (DBP), and SBP combined with DBP predict CVD events in the Veterans Affairs Diabetes Trial (VADT).

RESEARCH DESIGN AND METHODS

Participants in the VADT (n = 1,791) with hypertension received stepped treatment to maintain blood pressure below the target of 130/80 mmHg in standard and intensive glycemic treatment groups. Blood pressure levels of all subjects at baseline and On-Study were analyzed to detect associations with CVD risk. The primary outcome was the time from randomization to the first occurrence of myocardial infarction, stroke, congestive heart failure, surgery for vascular disease, inoperable coronary disease, amputation for ischemic gangrene, or CVD death.

RESULTS

Separated SBP ≥140 mmHg had significant risk at baseline (hazards ratio [HR] 1.508, P < 0.001) and On-Study (HR 1.469, P = 0.002). DBP <70 mmHg increased CVD events at baseline (HR 1.482, P < 0.001) and On-Study (HR 1.491, P < 0.001). Combined blood pressure categories indicated high risk for CVD events for SBP ≥140 with DBP <70 mmHg at baseline (HR 1.785, P = 0.03) and On-Study (HR 2.042, P = 0.003) and nearly all SBP with DBP <70 mmHg.

CONCLUSIONS

Increased risk of CVD events with SBP ≥140 mmHg emphasizes the urgency for treatment of systolic hypertension. Increased risk with DBP <70 mmHg, even when combined with SBP in guideline-recommended target ranges, supports a new finding in patients with type 2 diabetes. The results emphasize that DBP <70 mmHg in these patients was associated with elevated CVD risk and may best be avoided.Based on results of recent interventional trials (1–3), the question of whether or not intensive glucose control significantly reduces the risk of cardiovascular disease (CVD) in all patients with type 2 diabetes remains controversial. It may be beneficial in subgroups of these patients when severe hypoglycemia is avoided. Blood pressure (BP) control is consistently correlated with CVD events in studies of risk factors in type 2 diabetes. In the UK Prospective Diabetes Study, BP control was twice as effective as glucose control in preventing any diabetes end points (4,5). The Hypertension Optimal Treatment (HOT) study and the Appropriate Blood Pressure Control in Diabetes (ABCD) trial support improved BP control as a significant CVD event preventive factor in patients with diabetes (6–8). Both the American Diabetes Association (ADA) and the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC-7) recommend treatment of BP in patients with diabetes to a target of <130/<80 mmHg (9,10). Current evidence supports a systolic blood pressure (SBP) level of <140 mmHg, but there is sparse information to guide physicians as to how far the SBP and diastolic blood pressure (DBP) can be lowered safely and whether lower BP levels might be associated with increased risk. We analyzed the BP data collected during the Veterans Affairs Diabetes Trial (VADT) to learn whether specific levels of BP in patients with type 2 diabetes predict CVD events.The VADT is a 20-center 1,791-patient prospective study of intensive versus standard glucose treatment in patients with suboptimal responses to maximum oral agents or insulin. The main objective was to assess the benefit of intensive glucose control for up to 7 years on CVD events in patients with advanced type 2 diabetes. Other objectives included the assessment of the effects on microvascular and neurological complications, cognitive function, quality of life, and cost-effectiveness. BP, lipids, diet, and lifestyle were treated identically in both arms. By improving BP control in an identical manner in both glucose arms, VADT excluded the effect of BP differences in CVD events between treatment arms and reduced the overall risk of macrovascular complications during the trial. The initial results were published recently (1).     

Ketoacid Supplementation Partially Improves Metabolic Parameters in Patients on Peritoneal Dialysis

♦ Background:

A low protein diet supplemented with ketoacids has been shown to improve the metabolic profile, including insulin resistance, in patients with chronic kidney disease (CKD), but whether ketoacids alone exert similar effects is unknown. In this prospective randomized controlled trial, we aimed to evaluate the effects of ketoacid supplementation on insulin resistance, systemic inflammation, oxidative stress and endothelial dysfunction among 100 CKD patients undergoing peritoneal dialysis (PD).

♦ Methods:

Patients from one Chinese PD center were randomly assigned to take ketoacids (12 tablets per day) (n = 50) versus a control group (n = 50) for 6 months in an open-label parallelarm design. Daily protein intake of 0.8 – 1.2 g/kg/d and daily energy intake of 25 – 35 kcal/kg/d was prescribed to both groups. Insulin resistance was evaluated using homeostatic model assessment (HOMA-IR) index as the primary outcome. We assessed systemic inflammation using high-sensitive C-reactive protein (hs-CRP) and interleukin-6 (IL-6), oxidative stress using plasma oxidized low density lipoprotein (oxLDL), adipokines using leptin and adiponectin and endothelial dysfunction using serum soluble intercellular adhesion molecule-1 (sICAM) and soluble vascular adhesion molecule-1 (sVCAM) as secondary outcomes.

♦ Results:

There were no significant differences in baseline characteristics between the 2 groups except a slightly higher age in patients assigned to the intervention. A total of 89% of participants completed the 6-month intervention. There was no significant difference in the change of HOMA-IR values from baseline between groups after adjusting for baseline age, gender, body mass index and HOMA-IR. For secondary outcomes, hs-CRP varied significantly between groups (p = 0.02), increasing over time for the control group while remaining stable for the ketoacid group. Similarly, the leptin/adiponectin ratio (LAR) differed between groups (p < 0.001), remaining stable in the ketoacid group but increasing in the control group.

♦ Conclusion:

Ketoacid therapy administered for 6 months had no effect on HOMA-IR but resulted in improvements in hs-CRP and LAR, suggesting metabolic benefit. Future studies are needed to confirm these results and any potential benefit in vascular health of PD patients.     

Identification of Targets for Prevention of Peritoneal Catheter Tunnel and Exit-Site Infections in Low Incidence Settings

♦ Background:

Peritoneal catheter tunnel and exit-site infection (TESI) complicates the clinical course of peritoneal dialysis (PD) patients. Adherence to recommendations for catheter insertion, exit-site care, and management of Staphylococcus aureus (SAu) carriage reduces, but does not abrogate the risk of these infections.

♦ Objective:

To reappraise the risk profile for TESI in an experienced center with a long-term focus on management of SAu carriage and a low incidence of these infections.

♦ Method:

Following a retrospective, observational design, we investigated 665 patients incident on PD. The main study variable was survival to the first episode of TESI. We considered selected demographic, clinical, and technical variables, applying multivariate strategies of analysis.

♦ Main results:

The overall incidence of TESI was 1 episode/68.5 patient-months. Staphylococcus aureus carriage disclosed at inception of PD (but not if observed sporadically during follow-up) (hazard ratio [HR] 1.53, p = 0.009), PD started shortly after catheter insertion (HR 0.98 per day, p = 0.011), PD after kidney transplant failure (HR 2.18, p = 0.017), lower hemoglobin levels (HR 0.88 per g/dL, p = 0.013) and fast peritoneal transport rates (HR 2.92, p = 0.03) portended an increased risk of TESI. Delaying PD ≥ 30 days after catheter insertion markedly improved the probability of TESI. Carriage of methicillin-resistant SAu since the start of PD was associated with a high incidence of TESI by these bacteria. On the contrary, resistance to mupirocin did not predict such a risk, probably due to the use of an alternative regime in affected patients.

♦ Conclusions:

Adherence to current recommendations results in a low incidence of TESI in PD patients. Interventions on specific risk subsets have a potential to bring incidence close to negligible levels. Despite systematic screening and management, SAu carriage is still a predictor of TESI. Antibiotic susceptibility patterns may help to refine stratification of the risk of TESI by these bacteria. Early insertion of the peritoneal catheter should be considered whenever possible, to reduce the risk of later TESI.     

Effects of a Statewide Protocol for the Management of Peritoneal Dialysis-Related Peritonitis on Microbial Profiles and Antimicrobial Susceptibilities: A Retrospective Five-Year Review

♦ Background:

Peritonitis is a major complication of peritoneal dialysis (PD) and is associated with significant morbidity and mortality. Early empirical antibiotic therapy is recommended, with the choice of agents guided by local resistance patterns. As routine use of specific antimicrobial agents can drive resistance, regular assessment of causative organisms and their susceptibility to empirical therapy is essential.

♦ Methods:

We conducted a retrospective review of all PD peritonitis cases and positive PD fluid cultures obtained over a 5-year period in Western Australia following the introduction of a statewide protocol for the initial management of PD peritonitis with intraperitoneal vancomycin and gentamicin.

♦ Results:

The incidence of PD peritonitis decreased from 1 in 16 patient months (0.75/year at risk) to 1 in 29 patient months (0.41/year at risk) over the 5 years. There were 1,319 culture-positive samples and 1,069 unique isolates identified. Gram-positive bacteria accounted for 69.9% of positive cultures, with vancomycin resistance averaging 2% over the study period. Gram-negative bacteria accounted for 25.4% of positive cultures, with gentamicin resistance identified in an average of 8% of organisms. No increase in antimicrobial resistance to vancomycin or gentamicin occurred over the 5 years and there was no change in the proportion of gram-positive (69.9%), gram-negative (25.4%) or fungal (4.4%) organisms causing PD peritonitis.

♦ Conclusions:

Over time, the peritonitis rates have dramatically improved although the profile of causative organisms remains similar. Empirical treatment of PD peritonitis with intraperitoneal vancomycin and gentamicin remains efficacious, with high levels of susceptibility and no evidence that the introduction of this statewide empirical PD peritonitis treatment protocol is driving resistance to these agents.     

Novel Equations for Estimating Lean Body Mass in Peritoneal Dialysis Patients

♦ Objectives:

To develop and validate equations for estimating lean body mass (LBM) in peritoneal dialysis (PD) patients.

♦ Methods:

Two equations for estimating LBM, one based on mid-arm muscle circumference (MAMC) and hand grip strength (HGS), i.e., LBM-M-H, and the other based on HGS, i.e., LBM-H, were developed and validated with LBM obtained by dual-energy X-ray absorptiometry (DEXA). The developed equations were compared to LBM estimated from creatinine kinetics (LBM-CK) and anthropometry (LBM-A) in terms of bias, precision, and accuracy. The prognostic values of LBM estimated from the equations in all-cause mortality risk were assessed.

♦ Results:

The developed equations incorporated gender, height, weight, and dialysis duration. Compared to LBM-DEXA, the bias of the developed equations was lower than that of LBM-CK and LBM-A. Additionally, LBM-M-H and LBM-H had better accuracy and precision. The prognostic values of LBM in all-cause mortality risk based on LBM-M-H, LBM-H, LBM-CK, and LBM-A were similar.

♦ Conclusions:

Lean body mass estimated by the new equations based on MAMC and HGS was correlated with LBM obtained by DEXA and may serve as practical surrogate markers of LBM in PD patients.     

Peritoneal Dialysis Catheter Increases Leukocyte Recruitment in the Mouse Parietal Peritoneum Microcirculation and Causes Fibrosis

♦ Background:

The objective of this study was to examine the effects of a conventional dialysis solution and peritoneal catheter on leukocyte-endothelial cell interactions in the microcirculation of the parietal peritoneum in a subacute peritoneal dialysis (PD) mouse model.

♦ Methods:

An intraperitoneal (IP) catheter with a subcutaneous injection port was implanted into mice and, after a 2-week healing period, the animals were injected daily for 6 weeks with a 2.5% dextrose solution. Intravital microscopy (IVM) of the parietal peritoneum microcirculation was performed 4 hours after the last injection of the dialysis solution. Leukocyte-endothelial cell interactions were quantified and compared with catheterized controls without dialysis treatment and naïve mice.

♦ Results:

The number of rolling and extravascular leukocytes along with peritoneal fibrosis and neovascularization were significantly increased in the catheterized animals compared with naïve mice but did not significantly differ between the 2 groups of catheterized animals with sham injections or dialysis solution treatment.

♦ Conclusion:

The peritoneal catheter implant increased leukocyte rolling and extravasation, peritoneal fibrosis and vascularization in the parietal peritoneum independently from the dialysis solution treatment.     

Equivalent Fall Risk in Elderly Patients on Hemodialysis and Peritoneal Dialysis

♦ Background:

Accidental falls are common in the hemodialysis (HD) population. The high fall rate has been attributed to a combination of aging, kidney disease-related morbidity, and HD treatment-related hazards. We hypothesized that patients maintained on peritoneal dialysis (PD) would have fewer falls than those on chronic HD. The objective of this study was to compare the falls risk between cohorts of elderly patients maintained on HD and PD, using prospective data from a large academic dialysis facility.

♦ Methods:

Patients aged 65 years or over on chronic in-hospital HD and PD at the University Health Network were recruited. Patients were followed biweekly, and falls occurring within the first year recorded. Fall risk between the 2 groups was compared using both crude and adjusted Poisson lognormal random effects modeling.

♦ Results:

Out of 258 potential patients, 236 were recruited, assessed at baseline, and followed biweekly for falls. Of 74 PD patients, 40 (54%) experienced 86 falls while 76 out of 162 (47%) HD patients experienced a total of 305 falls (crude fall rate 1.25 vs 1.60 respectively, odds ratio [OR] falls in PD patients 0.78, 95% confidence interval [CI] 0.61 – 0.92, p = 0.04). After adjustment for differences in comorbidity, number of medications, and other demographic differences, PD patients were no less likely to experience accidental falls than HD patients (OR 1.63, 95% CI 0.88 – 3.04, p = 0.1).

♦ Conclusions:

We conclude that accidental falls are equally common in the PD population and the HD population. These data argue against post-HD hypotension as the sole contributor to the high fall risk in the dialysis population.     

Functional Disability in Older Adults Maintained on Peritoneal Dialysis Therapy

♦ Background:

Older in-center hemodialysis patients have a high burden of functional disability. However, little is known about patients on home chronic peritoneal dialysis (PD). As patients opting for home dialysis are expected to play a greater role in their own dialysis care, we hypothesized that a relatively low number of PD patients would require help with basic self-care tasks (ADL) and instrumental activities of daily living (IADL).

♦ Methods:

We used a cross-sectional study design to measure the proportion of patients aged 65 years and older undergoing outpatient PD who needed help with day-to-day activities. Patients living in nursing homes were excluded from the study. Functional dependence in ADL and IADL tasks were measured by the Barthel and Lawton Scales. Physical performance measures used included the timed up-and-go (TUG) test, chair stands and Folstein mini-mental score (MMSE).

♦ Results:

A total of 74 of 76 (97%) eligible PD patients participated. Patients had a mean age of 76.2 ± 7.5 years. Thirty-six percent had impaired MMSE scores, 69% were unable to stand from a chair without the use of their arms and 51% had abnormal TUG scores. Only 8 patients (11%) were fully independent for both ADL and IADL activities. Dependence in one or more ADL activity was reported by 64% of participants, while 89% reported dependence in one or more IADL.

♦ Conclusions:

Impaired physical and functional performance is common in older patients maintained on PD. Collaborative geriatric-renal programs may be beneficial within the dialysis community.     

Genetic Polymorphisms and Peritoneal Membrane Function

♦ Background:

Outcomes for peritoneal dialysis (PD) patients are affected by the characteristics of the peritoneal membrane, which may be determined by genetic variants. We carried out a systematic review of the literature to identify studies which assessed the association between genetic polymorphisms, peritoneal membrane solute transport, and clinical outcomes for PD patients.

♦ Methods:

The National Library of Medicine was searched using a variety of strategies. Studies which met our inclusion criteria were reviewed and data abstracted. Our outcomes of interest included: high transport status peritoneal membrane, risk for peritonitis, encapsulating peritoneal sclerosis (EPS), patient and technique survival. We combined data from studies which evaluated the same genetic polymorphism and the same outcome.

♦ Results:

We evaluated 18 relevant studies. All studies used a candidate gene approach. Gene polymorphisms in the interleukin (IL)-6 gene were associated with peritoneal membrane solute transport in several studies in different ethnic populations. Associations with solute transport and polymorphisms in endothelial nitric oxide synthase and receptor for advanced glycation end product genes were also identified. There was evidence of a genetic predisposition for peritonitis found in 2 studies, and for EPS in 1 study. Survival was found to be associated with a polymorphism in vascular endothelial growth factor and technique failure was associated with a polymorphism in the IL-1 receptor antagonist.

♦ Conclusions:

There is evidence that characteristics of the peritoneal membrane and clinical outcomes for PD patients have genetic determinants. The most consistent association was between IL-6 gene polymorphisms and peritoneal membrane solute transport.     

A Pilot Study Examining the Effects of Tolvaptan on Residual Renal Function in Peritoneal Dialysis for Diabetics

♦ Background:

For patients with end-stage renal disease (ESRD), peritoneal dialysis (PD) serves as a possible renal replacement therapy. However, most PD patients, particularly those with ESRD and diabetes mellitus, reportedly discontinue PD early, resulting in shorter survival periods and poorer prognosis because of overhydration. Recently, the vasopressin-2 receptor antagonist tolvaptan was approved for volume control in patients with heart failure. The present study aimed to identify the effects of tolvaptan in diabetic PD patients.

♦ Methods:

In this pilot study, the tolvaptan group (n = 12) were treated with 15 mg/day of tolvaptan 2 weeks after PD initiation and were prospectively analyzed for 1 year, and patients in the control group (n = 12) did not receive tolvaptan and were retrospectively analyzed for 1 year. In addition to the biochemical tests, echocardiograms, serum atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) levels, peritoneal Kt/V, and creatinine clearance (CCr) were examined at baseline and at 6 and 12 months after PD initiation.

♦ Results:

In the control group, the urine volume, renal Kt/V, and renal CCr levels consistently decreased; however, these parameters were stably maintained during the study period in the tolvaptan group. Atrial natriuretic peptide, CRP levels and the left ventricular mass index of the tolvaptan-treated group were significantly lower than those in the control group, whereas total protein and albumin levels were significantly higher at 6 and 12 months in the tolvaptan group. There were no obvious adverse effects.

♦ Conclusions:

These data suggest that tolvaptan may preserve residual renal function and improve volume control in PD patients with diabetes mellitus.     

Clinical Outcome of Home Hemodialysis in Patients with Previous Peritoneal Dialysis Exposure: Evaluation of the Integrated Home Dialysis Model

♦ Background:

Home dialysis is a cost-effective modality of renal replacement therapy associated with excellent outcomes. Peritoneal dialysis (PD) is the most common home-based modality, but technique failure remains a problem. Transfer from PD to home hemodialysis (HHD) allows the patient to continue with a home-based modality, but the outcomes of patients transitioning to HHD after PD are largely unknown.

♦ Methods:

In a retrospective cohort study, including all consecutive HHD patients between January 1996 and December 2011, we evaluated the outcomes of patients with previous PD exposure compared to those without. The primary outcome was the cumulative patient and technique survival. Secondary outcomes included time to first hospitalization and hospitalization rate. Data were compared using the log-rank test and a multivariable Cox proportional hazards model.

♦ Results:

Among our cohort of 207 consecutive HHD patients, 35 (17%) had previous exposure to PD. Median renal replacement therapy (RRT) vintage (12.3 years, interquartile range (IQR) 8.5 – 18.9 vs 0.9 years, IQR 0.2 – 7.5, p < 0.001) and Charlson comorbidity index (CCI) (4, IQR 2 – 6 vs 3, IQR 2 – 4, p = 0.044) were higher among patients with PD exposure than those without. Despite the difference in vintage, cumulative patient and technique survival was similar in the two groups, in both unadjusted (log-rank p = 0.893) and Cox adjusted models (hazard ratio (HR) 1.15, 95% confidence interval (CI) 0.51 – 2.59) for patients with PD exposure compared to those without. The time to first hospitalization was shorter in patients with previous PD exposure compared to PD-naïve patients (log-rank p = 0.021). This association was preserved in the Cox proportional model (HR 1.65, 95% CI 1.08 – 2.54).

♦ Conclusion:

Despite a higher burden of comorbidity, patients with previous PD exposure had similar cumulative patient and technique survival on HHD compared to those without PD exposure. Whenever possible, HHD should be considered in PD patients in need of a new dialysis modality.     

Serum 25-Hydroxyvitamin D Level Could Predict the Risk for Peritoneal Dialysis-Associated Peritonitis

♦ Background:

As an immune system regulator, vitamin D is commonly deficient among patients on peritoneal dialysis (PD), which may contribute to their impaired immune function and increased risk for PD-related peritonitis. In this study, we aimed to investigate whether vitamin D deficiency could predict the risk of peritonitis in a prospective cohort of patients on PD.

♦ Methods:

We collected 346 prevalent and incident PD patients from 2 hospitals. Baseline demographic data and clinical characteristics were recorded. Serum 25-hydroxyvitamin D (25[OH]D) was measured at baseline and prior to peritonitis. The mean doses of oral active vitamin D used during the study period were also recorded. The outcome was the occurrence of peritonitis.

♦ Results:

The mean age of patients and duration of PD were 58.95 ± 13.67 years and 28.45 (15.04 – 53.37) months, respectively. Baseline 25(OH)D level was 16.15 (12.13 – 21.16) nmol/L, which was closely associated with diabetic status, longer PD duration, malnutrition, and inflammation. Baseline serum 25(OH)D predicted the occurrence of peritonitis independently of active vitamin D supplementation with a hazard ratio (HR) of 0.94 (95% confidence interval [CI] 0.90 – 0.98) after adjusting for recognized confounders (age, gender, dialysis duration, diabetes, albumin, residual renal function, and history of peritonitis). Compared to the low tertile, middle and high 25(OH)D level tertiles were associated with a decreased risk for peritonitis with HRs of 0.54 (95% CI 0.31 – 0.94) and 0.39 (95% CI 0.20 – 0.75), respectively.

♦ Conclusions:

Vitamin D deficiency evaluated by serum 25(OH)D rather than active vitamin D supplementation is closely associated with a higher risk of peritonitis.     

Socio-Economic Status and Peritonitis in Australian Non-Indigenous Peritoneal Dialysis Patients

♦ Background:

The aim of the present study was to investigate the relationship between socio-economic status (SES) and peritoneal dialysis (PD)-related peritonitis.

♦ Methods:

Associations between area SES and peritonitis risk and outcomes were examined in all non-indigenous patients who received PD in Australia between 1 October 2003 and 31 December 2010 (peritonitis outcomes). SES was assessed by deciles of postcode-based Australian Socio-Economic Indexes for Areas (SEIFA), including Index of Relative Socio-economic Disadvantage (IRSD), Index of Relative Socio-economic Advantage and Disadvantage (IRSAD), Index of Economic Resources (IER) and Index of Education and Occupation (IEO).

♦ Results:

7,417 patients were included in the present study. Mixed-effects Poisson regression demonstrated that incident rate ratios for peritonitis were generally lower in the higher SEIFA-based deciles compared with the reference (decile 1), although the reductions were only statistically significant in some deciles (IRSAD deciles 2 and 4 – 9; IRSD deciles 4 – 6; IER deciles 4 and 6; IEO deciles 3 and 6). Mixed-effects logistic regression showed that lower probabilities of hospitalization were predicted by relatively higher SES, and lower probabilities of peritonitis-associated death were predicted by less SES disadvantage status and greater access to economic resources. No association was observed between SES and the risks of peritonitis cure, catheter removal and permanent hemodialysis (HD) transfer.

♦ Conclusions:

In Australia, where there is universal free healthcare, higher SES was associated with lower risks of peritonitis-associated hospitalization and death, and a lower risk of peritonitis in some categories.     

Peritoneal Dialysis Can Be an Option for Dominant Polycystic Kidney Disease: an Observational Study

♦ Background:

Autosomal dominant polycystic kidney disease (ADPKD) has been considered a relative contraindication for peritoneal dialysis (PD), although there are few specific studies available.

♦ Methods:

A multicenter historical prospective matched-cohort study was conducted to describe the outcome of ADPKD patients who have chosen PD. All ADPKD patients starting PD (n = 106) between January 2003 and December 2010 and a control group (2 consecutive patients without ADPKD) were studied. Mortality, PD-technique failure, peritonitis, abdominal wall leaks and cyst infections were compared.

♦ Results:

Patients with ADPKD had similar age but less comorbidity at PD inclusion: Charlson comorbidity index (CCI) 4.3 (standard deviation [SD] 1.6) vs 5.3 (SD 2.5) p < 0.001, diabetes mellitus 5.7% vs 29.2%, p < 0.001 and previous cardiovascular events 10.4% vs 27.8%, p < 0.001. No differences were observed in clinical events that required transient transfer to hemodialysis, nor in peritoneal leakage episodes or delivered dialysis dose. The cyst infection rate was low (0.09 episodes per patient-year) and cyst infections were not associated to peritonitis episodes. Overall technique survival was similar in both groups. Permanent transfer to hemodialysis because of surgery or peritoneal leakage was more frequent in ADPKD. More ADPKD patients were included in the transplant waiting list (69.8 vs 58%, p = 0.04) but mean time to transplantation was similar (2.08 [1.69 – 2.47] years). The mortality rate was lower (2.5 vs 7.6 deaths/100 patient-year, p = 0.02) and the median patient survival was longer in ADPKD patients (6.04 [5.39 – 6.69] vs 5.57 [4.95 – 6.18] years, p = 0.024).

♦ Conclusion:

Peritoneal dialysis is a suitable renal replacement therapy option for ADPKD patients.     

Embedded Catheters: Minimizing Excessive Embedment Time and Futile Placement while Maintaining Procedure Benefits

♦ Background:

Embedding peritoneal catheters far in advance of anticipated need may successfully commit patients to their modality choice and reduce central venous catheter use but can be complicated by excessive embedment periods and futile catheter placement.

♦ Objective:

Embedded catheter outcomes were studied to identify factors that minimize inordinate embedment time and futile placement while maintaining procedure benefits.

♦ Methods:

Clinical and laboratory data were examined in 107 patients with embedded catheters that were either externalized, remained embedded, or were futilely placed.

♦ Results:

Externalization of 84 catheters was performed after a median embedment period of 9.4 months. Flow dysfunction occurred in 14.3% of externalized catheters. Overall function rate was 98.8% after laparoscopic revision. One patient changed their mind about modality choice. Except for 1 patient hospitalized acutely in a facility unfamiliar with embedded catheters, none remaining on a peritoneal dialysis pathway initiated dialysis with a central venous catheter. Including catheters with extremely long embedment periods, the incidence of futile placement was 13.1%. Multiple regression analysis identified estimated glomerular filtration rate (eGFR) and serum albumin as the 2 variables best associated with catheter embedment duration (r² = 0.44, p < 0.0001). Diabetic nephropathy was statistically more likely to be associated with lower serum albumin values (p < 0.0001); however, no association was noted between diabetic status and embedment duration (p = 0.62).

♦ Conclusions:

Timing of the embedment procedure should include appraisal of both eGFR and serum albumin. Appropriate consideration of these values together may help minimize excessive embedment periods and decrease futile placements while preserving procedure benefits.     

The Association of Effluent Ca125 with Peritoneal Dialysis Technique Failure

♦ Background and objectives:

Cancer antigen 125 (CA125) reflects the mesothelial cell mass lining the peritoneal membrane in individual patients. A decline or absence of mesothelial cells can be observed with duration of peritoneal dialysis (PD) therapy. Technique failure due to peritoneal membrane malfunction becomes of greater importance after 2 years of PD therapy in comparison to the initial period. In this study, we aimed to investigate the association between effluent CA125 and technique survival in incident PD patients with a PD therapy period of at least 2 years.

♦ Methods:

Within the Netherlands Cooperative Study on the Adequacy of Dialysis (NECOSAD), a Dutch multicenter cohort including 2,000 incident dialysis patients, we identified all PD patients who developed technique failure after 2 years of PD therapy and randomly selected a number of them as cases in a nested case-control study. Controls were PD patients matched on follow-up time without technique failure. Cases and controls were included if they had a dialysate specimen available within 24 ± 6 months of PD therapy for retrospective CA125 determinations. Odds ratios for technique failure related to CA125 were estimated. We used a prospective cohort with incident PD patients from the Academic Medical Center–University of Amsterdam (AMC) for replication of effect estimates. In these patients, absolute risk of technique failure was estimated and related to effluent CA125 levels.

♦ Results:

A total of 38 PD patients were selected from the NECOSAD cohort. From the AMC cohort as replication cohort, 91 PD patients were included. Incidence rates of PD technique failure per 100 patient-years were 16.3 in the NECOSAD cohort and 12.9 in the AMC cohort. In both study populations CA125 levels below 12 – 14 kU/L were associated with an increased risk for technique failure. Technique survival rates in the AMC were 87% in patients with levels of CA125 above 12.1 kU/L and 65% for those with CA125 levels below this threshold after a maximum 5-year follow-up.

♦ Conclusions:

Patients with high CA125 levels after at least 2 years of PD therapy tend to have better technique survival than patients with low CA125 levels. These results support the importance of effluent CA125 as a risk factor for dropout in long-term PD therapy.     

The Impact of Transfer from Hemodialysis on Peritoneal Dialysis Technique Survival

♦ Background:

A significant proportion of peritoneal dialysis (PD) patients receive an initial period of hemodialysis (HD) before transitioning to PD (“PD-switch”). We sought to better understand the risks of PD technique failure (TF) and mortality for those patients compared with patients starting with PD as their first dialysis modality (“PD-first”).

♦ Methods:

Using Canadian Organ Replacement Register data, we compared the risk of PD TF between PD-first and PD-switch patients within the first year after HD initiation. In a secondary analysis, the PD-switch patients were stratified into three groups based on timing of the switch from initial HD to PD as follows: 0 – 90 days, 91 – 180 days, and 181 – 365 days. Each group was compared with PD-first patients for risk of PD TF and death.

♦ Results:

Between 2001 and 2010, 9404 patients initiated PD as their first renal replacement therapy, and 3757 switched from HD to PD. After multivariable adjustment, the risk of PD TF was higher among PD-switch patients than among PD-first patients [adjusted hazard ratio (AHR): 1.37; 95% confidence interval (CI): 1.26 to 1.49], particularly within the first year after the switch from HD to PD (AHR: 1.51; 95% CI: 1.36 to 1.68). There was no association between time on HD within the first year and subsequent risk of PD TF. For all the stratified PD-switch groups, death rates were higher than those for PD-first patients.

♦ Conclusions:

Compared with patients who start renal replacement therapy with PD, those who transfer from HD to PD within the first year on dialysis experience higher rates of PD TF and death, with the highest risk being observed in the initial year after the switch to PD.     

The Mutual Relationship Between Peritonitis and Peritoneal Transport

♦ Background:

Preservation of the peritoneum is required for long-term peritoneal dialysis (PD). We investigated the effect of multiple peritonitis episodes on peritoneal transport.

♦ Methods:

Prospectively collected data from 479 incident PD patients treated between 1990 and 2010 were analyzed, using strict inclusion criteria: follow-up of at least 3 years with the availability of a Standard Peritoneal Permeability Analysis (SPA) in the first year after start of PD and within the third year of PD, without peritonitis preceding the first SPA. For the purpose of the study, we only included patients who remained peritonitis-free (n = 28) or who experienced 3 or more peritonitis episodes (n = 16).

♦ Results:

At baseline the groups were similar with regard to small solute and fluid transport. However, the frequent peritonitis group had lower peritoneal protein clearances compared to the no peritonitis group, resulting in lower dialysate concentrations of proteins: albumin 196.5 mg/L vs 372.5 mg/L, IgG 36.4 mg/L vs 65.0 mg/L, and α-2-macroglobulin (A2M) 1.9 mg/L vs 3.6 mg/L, p <0.01. No differences in serum concentrations were present. A comparison between the transport slopes over time in both groups showed a positive time trend of mass transfer area coefficient (MTAC) creatinine (p = 0.03) and glucose absorption (p = 0.09) and a negative trend of transcapillary ultrafiltration (p = 0.06), when compared to the no peritonitis group. Frequent peritonitis did not affect free water transport.

♦ Conclusions:

Slow initial peritoneal transport rates of serum proteins result in lower dialysate concentrations, and likely a lower opsonic activity, which is a risk factor for peritonitis. Patients with frequent peritonitis show an increase in small solute transport and a concomitant decrease of ultrafiltration. In long-term peritonitis-free PD patients, small solute transport decreased, while ultrafiltration increased. This suggests that frequent peritonitis leads to an increase of the vascular peritoneal surface area without all the structural membrane alterations that may develop after long-term PD.