The association between dialysis modality and the risk for dialysis technique and non-dialysis technique-related infections.

BACKGROUND: Infections are a major cause of morbidity and mortality among dialysis patients. Dialysis modality has been hypothesized to be a potential immunomodulatory factor. The objective of this study was to determine the influence of the first dialysis modality on the risk for infections on dialysis. METHODS: Our study was conducted utilizing the Netherlands Cooperative Study on the Adequacy of Dialysis (NECOSAD) cohort of incident dialysis patients. Medical records of all patients from two tertiary care university hospitals and three regional hospitals were reviewed using pre-specified criteria. Information about infections was collected from the start of dialysis until death, modality switch, study withdrawal, kidney transplantation or at the end of the study. Age-standardized incidence rates for infections were calculated. Poisson regression analysis was used to calculate adjusted incidence rate ratios (IRRs). RESULTS: In total, 452 patients, of whom 285 started with haemodialysis (HD) and 167 with peritoneal dialysis (PD), were included. The median follow-up time on the first dialysis modality was similar for HD and PD, 1.8 and 2.0 dialysis years, respectively. During the first 6 months, the age-standardized infection incidence rate was higher on HD compared with PD patients (P = 0.02). Overall, PD patients had a higher infection risk [adjusted IRR: 1.65, 95% confidence interval (CI): 1.34-2.03], which could be attributed to a 4-fold increased risk for dialysis technique-related infections. The risk for non-dialysis technique-related infections was lower in PD patients (adjusted IRR: 0.56, 95% CI: 0.40-0.79). CONCLUSIONS: Overall, PD patients carry a higher risk for infections. Interestingly, the risk for non-dialysis technique-related infections was higher in HD patients. The links between dialysis modality and the immune system are expected to explain this difference, but future studies are needed to test these assumptions.

The -174G/C variant of IL6 as risk factor for mortality and technique failure in a large cohort of peritoneal dialysis patients.

BACKGROUND: Functional variants in the IL6 gene, in particular the -174G/C polymorphism (rs1800795), affect the mortality risk in dialysis patients. Peritoneal dialysis (PD) patients harbouring the C allele of the -174G/C polymorphism of IL6 showed faster peritoneal transport. The aim of this study was to investigate this IL6 variant as risk factor for mortality and technique failure in a large cohort of Caucasian PD patients. METHODS: A Dutch multicentre cohort of 398 incident PD patients (NECOSAD) was analysed. Survival analysis was performed for death and technique failure with a maximum follow-up of 5 years. A combined PD cohort from Amsterdam (Academic Medical Center, N = 71) and Brussels (Université catholique de Louvain Medical School, N = 102) was used for independent replication. RESULTS: In NECOSAD, 105 patients died on dialysis [incidence rate 10.3/100 person-years (py)], and 138 patients experienced technique failure (16.2/100 py), with peritonitis as important cause. Patients with the C/C genotype had a 71% increased mortality risk compared to patients with the G/G genotype (95% confidence interval 0.98-2.98); this effect was mainly a long-term effect: a 2.7-fold increased mortality risk was found in patients having survived 2 years since the start on dialysis, and a 1.7-fold increased risk for the combined end point (mortality or technique failure). In the combined replication cohort, no increased risks were found in patients with the C/C genotype. CONCLUSIONS: The C/C genotype of the -174G/C polymorphism was associated with an increased mortality risk in 398 Dutch incident PD patients. The existence of substantial differences between the two academic replication cohorts and the discovery cohort from NECOSAD and the limited power of these cohorts prevented an independent replication of the NECOSAD findings.

Development and validation of the Consumer Quality index instrument to measure the experience and priority of chronic dialysis patients.

BACKGROUND: Patient experience is an established indicator of quality of care. Validated tools that measure both experiences and priorities are lacking for chronic dialysis care, hampering identification of negative experiences that patients actually rate important. METHODS: We developed two Consumer Quality (CQ) index questionnaires, one for in-centre haemodialysis (CHD) and the other for peritoneal dialysis and home haemodialysis (PHHD) care. The instruments were validated using exploratory factor analyses, reliability analysis of identified scales and assessing the association between reliable scales and global ratings. We investigated opportunities for improvement by combining suboptimal experience with patient priority. RESULTS: Sixteen dialysis centres participated in our study. The pilot CQ index for CHD care consisted of 71 questions. Based on data of 592 respondents, we identified 42 core experience items in 10 scales with Cronbach's α ranging from 0.38 to 0.88; five were reliable (α ≥ 0.70). The instrument identified information on centres' fire procedures as the aspect of care exhibiting the biggest opportunity for improvement. The pilot CQ index PHHD comprised 56 questions. The response of 248 patients yielded 31 core experience items in nine scales with Cronbach's α ranging between 0.53 and 0.85; six were reliable. Information on kidney transplantation during pre-dialysis showed most room for improvement. However, for both types of care, opportunities for improvement were mostly limited. CONCLUSIONS: The CQ index reliably and validly captures dialysis patient experience. Overall, most care aspects showed limited room for improvement, mainly because patients participating in our study rated their experience to be optimal. To evaluate items with high priority, but with which relatively few patients have experience, more qualitative instruments should be considered.

Trimestral variations of C-reactive protein, interleukin-6 and tumour necrosis factor-α are similarly associated with survival in haemodialysis patients.

BACKGROUND: The impact of intra-individual changes of inflammatory markers [other than C-reactive protein (CRP)] on mortality in haemodialysis (HD) patients is unknown. We therefore studied survival in relation to trimestral variations of CRP, interleukin-6 (IL-6) and tumour necrosis factor-α (TNF-α). METHODS: In 201 prevalent HD patients from the Mapping of Inflammatory Markers in Chronic Kidney Disease cohort, serum CRP, IL-6 and TNF-α were measured 3 months apart and survival was assessed during follow-up. Based on fluctuations along tertiles of distribution, four patterns were defined for each inflammatory marker: stable low, decrease, increase and stable high. Hazard ratios were calculated by the Cox proportional hazard model, and Pearson's test was used to correlate changes. CRP analyses were replicated in 472 incident HD patients from the Netherlands Cooperative Study on the Adequacy of Dialysis. RESULTS: Patients with persistently elevated CRP values had the worst mortality in crude [HR 2.98 (95% CI 1.71-5.20)] and adjusted [2.79 (1.58-4.94)] Cox models, together with those who increased in their CRP levels [crude 3.27 (1.91-5.60); adjusted 3.13 (1.79-5.45)]. Similar survival patterns were observed for IL-6 and TNF-α variation categories. Correlations among these changes were, however, not strong. In the replication cohort, individuals with persistently elevated CRP values also showed the highest mortality risk [crude 3.38 (2.31-4.94); adjusted 2.33 (1.58-3.45)]. CONCLUSIONS: Trimestral variations of TNF-α, IL-6, and CRP are similarly associated with survival in HD patients. The agreement between changes of these biomarkers was low, suggesting that different pathways may trigger each of these markers.

Changes in quality of life over time--Dutch haemodialysis patients and general population compared.

BACKGROUND: Improving the health-related quality of life (HRQOL) for haemodialysis patients is a considerable challenge. The aim of the present study was to compare changes in HRQOL in haemodialysis patients with those observed in the general population over a 10-year period and explore factors that might explain possible differences. METHODS: We compared 126 haemodialysis patients assessed in 1995 in the Netherlands Cooperative Study on the Adequacy of Dialysis-1 (NECOSAD-I) with 515 patients enrolled in 2006 in the ongoing Convective Transport Study (CONTRAST). Changes in HRQOL in these cohorts were compared with two representative samples from the general Dutch population, assessed in 1992 (n = 1,063) and 2001 (n = 10,600). HRQOL was measured with the SF-36 questionnaire. Differences in HRQOL were analysed with ANCOVA to adjust for demographic variables. To assess possible differences, we used multivariable regression analysis. RESULTS: HRQOL in haemodialysis patients in 2006 [CONTRAST, mean age 63 ± 14 years (SD), 62% male] was significantly better than in 1995 (NECOSAD-I, 59 ± 16 years, 53% male) in four domains of the SF-36: bodily pain (+ 5 points, P = 0.009), vitality (+ 7, P < 0.001), role-emotional (+ 14, P < 0.001) and mental health (+ 8, P < 0.001), after adjusting for demographic variables. This increment could partly be explained by improved haemoglobin and phosphate levels. Compared to the general population, HRQOL improvement was most outspoken in two domains: bodily pain (+ 6, P = 0.01) and role-emotional (+ 8, P = 0.007). CONCLUSIONS: This study showed an improvement of HRQOL in haemodialysis patients over an 11-year period of time, independent of global changes in the general population.

Variations in C-reactive protein during a single haemodialysis session do not associate with mortality.

BACKGROUND: An increase in C-reactive protein (CRP) levels during a single haemodialysis (HD) session has been associated with mortality. These associations, however, are difficult to understand from the current understanding of CRP metabolism. METHODS: In 190 Swedish haemodialysis (HD) patients from the Mapping of Inflammatory Markers in Chronic Kidney Disease (MIMICK) cohort, CRP was measured before and after a HD session. During follow-up, events of death and censoring were recorded, and hazard ratios were calculated and analysed as a function of CRP variation. Results were replicated in 94 Dutch HD patients from the Netherlands Cooperative Study on the Adequacy of Dialysis (NECOSAD). In this cohort, also correlation and kappa statistics were calculated to assess concordance in CRP changes amid multiple dialysis sessions from the same individuals. RESULTS: In both cohorts, mean CRP values did not increase during a single HD session. In the MIMICK, median (interquartile range) dialysis vintage was 29.0 (14.8-57.0) months. In both crude [hazard ratio (95% confidence interval): 1.008 (0.971-1.047)] and multivariate Cox models [0.996 (0.949-1.046)], no association was observed with mortality. In the NECOSAD, individuals endured 6.0 (6.0-12.0) months on dialysis. No association was found with mortality neither in a crude [0.961 (0.908-1.018)] nor in an adjusted analysis [0.978 (0.923-1.037)]. Finally, the concordance between changes in different sessions was poor. CONCLUSIONS: CRP changes during a single HD session do not associate with mortality, thereby adding to the biological uncertainty concerning the ability of CRP to rise in such a short period.

Significant Decreasing Incidence of Encapsulating Peritoneal Sclerosis in the Dutch Population of Peritoneal Dialysis Patients.

The Dutch Encapsulating Peritoneal Sclerosis (EPS) Registry was started in 2009. Cases were identified by contacting all Dutch nephrologists twice yearly. The predefined criteria for EPS allowed for inclusion of patients with diagnosed and suspected EPS. Cases registered between January 2009 and January 2015 were analyzed with follow-up until September 2015. Fifty-three EPS cases were identified, of which 28.3% were post-transplantation EPS cases. Fourteen patients were initially categorized as suspected EPS, of whom 13 developed EPS. A remarkable 6-fold decrease in the yearly incidence of EPS was observed, from 0.85% in 2009 to 0.14% in 2014. This decrease could not be explained by a decrease in the number of PD patients or average duration of PD treatment in this period. Two-year survival of EPS patients was 52%. The use of tamoxifen and surgical interventions increased significantly over the years. Tamoxifen-treated cases showed a trend to better patient survival and post-transplantation EPS had a significantly favorable outcome. In conclusion, the incidence of EPS has declined significantly in the Netherlands from 2009 to 2014.

How baseline, new-onset, and persistent depressive symptoms are associated with cardiovascular and non-cardiovascular mortality in incident patients on chronic dialysis.

OBJECTIVE: Depressive symptoms are associated with mortality among patients on chronic dialysis therapy. It is currently unknown how different courses of depressive symptoms are associated with both cardiovascular and non-cardiovascular mortality. METHODS: In a Dutch prospective nation-wide cohort study among incident patients on chronic dialysis, 1077 patients completed the Mental Health Inventory, both at 3 and 12months after starting dialysis. Cox regression models were used to calculate crude and adjusted hazard ratios (HRs) for mortality for patients with depressive symptoms at 3months only (baseline only), at 12months only (new-onset), and both at 3 and 12months (persistent), using patients without depressive symptoms at 3 and 12months as reference group. RESULTS: Depressive symptoms at baseline only seemed to be a strong marker for non-cardiovascular mortality (HRadj 1.91, 95% CI 1.26-2.90), whereas cardiovascular mortality was only moderately increased (HRadj 1.41, 95% CI 0.85-2.33). In contrast, new-onset depressive symptoms were moderately associated with both cardiovascular (HRadj 1.66, 95% CI 1.06-2.58) and non-cardiovascular mortality (HRadj 1.46, 95% CI 0.97-2.20). Among patients with persistent depressive symptoms, a poor survival was observed due to both cardiovascular (HRadj 2.14, 95% CI 1.42-3.24) and non-cardiovascular related mortality (HRadj 1.76, 95% CI 1.20-2.59). CONCLUSION: This study showed that different courses of depressive symptoms were associated with a poor survival after the start of dialysis. In particular, temporary depressive symptoms at the start of dialysis may be a strong marker for non-cardiovascular mortality, whereas persistent depressive symptoms were associated with both cardiovascular and non-cardiovascular mortality.

Venous and arterial thrombosis in dialysis patients.

Whether the risk of both venous and arterial thrombosis is increased in dialysis patients as compared to the general population is unknown. In addition, it is unknown which subgroups are at highest risk. Furthermore, it is unknown whether having a history of venous thrombosis or arterial thrombosis prior to dialysis treatment increases mortality risk. A total of 455 dialysis patients were followed for objectively verified symptomatic thrombotic events between January 1997 and June 2009. The incidence rates in dialysis patients as compared to the general population was 5.6-fold (95% CI 3.1-8.9) increased for venous thrombosis, 11.9-fold (95% CI 9.3-14.9) increased for myocardial infarction, and 8.4-fold (95% CI 5.7-11.5) increased for ischaemic stroke. The combination of haemodialysis, lowest tertile of albumin, history of venous thrombosis, and malignancy was associated with subsequent venous thrombosis. Increased age, renal vascular disease, diabetes, high cholesterol levels, history of venous thrombosis, and history of arterial thrombosis were associated with subsequent arterial thrombosis. The all-cause mortality risk was 1.9-fold (95% CI 1.1-3.3) increased for patients with a history of venous thrombosis and 1.9-fold (95% CI 1.4-2.6) increased for patients with a history of arterial thrombosis. A potential limitation of this study was that in some risk categories associations with venous thrombosis did not reach statistical significance due to small numbers. In conclusion, dialysis patients have clearly elevated risks of venous thrombosis and arterial thrombosis and occurrence of venous thrombosis or arterial thrombosis prior to the start of dialysis is associated with an increased mortality risk.

alpha-Galactosidase A deficiency in Dutch patients on dialysis: a critical appraisal of screening for Fabry disease.

INTRODUCTION: Fabry disease or alpha-galactosidase A (alpha-Gal A) deficiency is an X-linked lysosomal storage disorder that often leads to renal insufficiency in males and occasionally in females. The disease is rare, but its prevalence may be underestimated due to its variable clinical picture. Enzyme supplementation therapy with rHu-alphaGal A is currently available. Limited experience has so far shown that therapy may at best stabilize renal function. Despite these preliminary findings, much effort is being put into screening high-risk groups for undiagnosed alpha-Gal A deficiency. We studied the prevalence of alpha-Gal A deficiency in a Dutch dialysis cohort to establish possible underdiagnosis. We discuss the benefits of screening for Fabry disease. METHODS: Activity of alpha-Gal A in whole blood was measured in a group of 508 male Dutch dialysis patients. RESULTS: Of the 508 patients studied only one patient, already known with Fabry disease, had a alpha-Gal A deficiency, a prevalence of 0.22% (95 CI 0-1.1%). CONCLUSIONS: No undiagnosed Fabry patients were found, indicating that in our studied cohort there is no large-scale underestimation of its prevalence. Even though screening of dialysis patients for Fabry disease might identify patients who remain otherwise unrecognized, screening of high-risk populations for alpha-Gal A deficiency should be carried out with caution since long-term efficacy of treatment is currently unknown.