The Influence of Renal Centre and Patient Sociodemographic Factors on Home Haemodialysis Prevalence in the UK

BACKGROUND

In the United Kingdom, socioeconomic disadvantage has been associated with lower use of home dialysis, mostly peritoneal dialysis. In this study, we explore the role of a patient's sociodemographic, socioeconomic differences and the centre's influence on home haemodialysis (HD) prevalence.

METHODS

Data is derived from the cross-sectional arm of the UK multi-centre study investigating barriers and enablers of home HD (BASIC-HHD study). Centres were classified as low- (<3%), medium- (5-8%) and high-prevalence groups (>8%). Sociodemographic and socioeconomic status data were ascertained. Patients were enrolled in hospital HD (n = 213), home HD (n = 93) and predialysis groups (n = 222).

RESULTS

The treating renal centre to which the patient belonged was significantly associated with a patient's modality in prevalent HD groups and modality-choice in the "predialysis" group, in confounder-adjusted multivariable analyses. Non-white ethnicity was associated with lower odds of self-care dialysis modality choice (OR 0.21, 95% CI 0.07-0.62) and lower odds of home HD uptake in the prevalent HD group (OR 0.24, 95% CI 0.07-0.80). Other significant associations of home HD uptake in the HD cohort included lower age (OR 0.59, 95% CI 0.39-0.89), higher education (OR 2.99, 95% CI 1.25-7.16), home ownership (OR 0.26, 95% CI 0.09-0.70), childcare responsibility (OR 0.22, 95% CI 0.08-0.66) and unrestricted mobility (OR 0.31, 95% CI 0.11-0.91).

CONCLUSION

"Centre" effect accounts for variation in home HD prevalence between renal units after accounting for sociodemographic parameters and co-morbidities. Unit practices and attitudes to home HD are likely to have a dominating impact on home HD prevalence rates and these aspects need to be explored systematically at the organisational level.

The Burden of Cognitive Impairment in Patients With End-Stage Renal Disease and Impact on Dialysis Modality Choice

Introduction

Kidney disease is associated with significant cognitive dysfunction. Subjective reports of cognitive ability have not been studied extensively in chronic kidney disease. We investigated the association between objective and subjective cognitive functions in predialysis patients and their association with self-care dialysis modality choice.

Methods

Cross-sectional data from the Barriers to Successful Implementation of Care in Home Haemodialysis study were used for the study of cognition in 220 predialysis patients. The data were used to ascertain the demographics, clinical, laboratory, and neuropsychometric variables. The latter includes Trail Making Tests (TMT) parts A and B, Modified Mini Mental State Examination, and metacognition questionnaire for subjective assessment of one's cognitive ability. The outcome variable was fully assisted and self-care dialysis modality choice.

Results

Within the study cohort, 90 patients chose fully assisted hemodialysis and 114 patients chose self-care dialysis. The median Modified Mini Mental State Examination, TMT part A, and TMT part B scores were greater for the assisted versus the self-care group. Metamemory was not significantly different between groups, but the metaconcentration score was significantly worse in the group choosing assisted dialysis. Higher (i.e., better) metaconcentration scores were significantly associated with the self-care modality choice in the univariate and hierarchical regression analyses. Adjusted and unadjusted analyses showed a significant association between perceived concentration and TMT part B scores (P < 0.01). With every 1.6-minute increase in TMT part B score, there was a 1-unit reduction in metaconcentration score, and the latter was associated with 20% lower odds of choosing self-care dialysis over a fully assisted dialysis modality.

Discussion

Patients' self-perception of cognitive ability is a significant predictor of self-care dialysis modality choice. Subjective report of "metaconcentration" is also strongly associated with poorer outcome on the TMT part B.

Genetic risk variants for membranous nephropathy: extension of and association with other chronic kidney disease aetiologies

Background

Membranous nephropathy (MN) is a common cause of nephrotic syndrome in adults. Previous genome-wide association studies (GWAS) of 300 000 genotyped variants identified MN-associated loci at HLA-DQA1 and PLA2R1.

Methods

We used a combined approach of genotype imputation, GWAS, human leucocyte antigen (HLA) imputation and extension to other aetiologies of chronic kidney disease (CKD) to investigate genetic MN risk variants more comprehensively. GWAS using 9 million high-quality imputed genotypes and classical HLA alleles were conducted for 323 MN European-ancestry cases and 345 controls. Additionally, 4960 patients with different CKD aetiologies in the German Chronic Kidney Disease (GCKD) study were genotyped for risk variants at HLA-DQA1 and PLA2R1.

Results

In GWAS, lead variants in known loci [rs9272729, HLA-DQA1, odds ratio (OR) = 7.3 per risk allele, P = 5.9 × 10^-27 and rs17830558, PLA2R1, OR = 2.2, P = 1.9 × 10^-8] were significantly associated with MN. No novel signals emerged in GWAS of X-chromosomal variants or in sex-specific analyses. Classical HLA alleles (DRB1*0301-DQA1*0501-DQB1*0201 haplotype) were associated with MN but provided little additional information beyond rs9272729. Associations were replicated in 137 GCKD patients with MN (HLA-DQA1: P = 6.4 × 10^-24; PLA2R1: P = 5.0 × 10^-4). MN risk increased steeply for patients with high-risk genotype combinations (OR > 79). While genetic variation in PLA2R1 exclusively associated with MN across 19 CKD aetiologies, the HLA-DQA1 risk allele was also associated with lupus nephritis (P = 2.8 × 10^-6), type 1 diabetic nephropathy (P = 6.9 × 10^-5) and focal segmental glomerulosclerosis (P = 5.1 × 10^-5), but not with immunoglobulin A nephropathy.

Conclusions

PLA2R1 and HLA-DQA1 are the predominant risk loci for MN detected by GWAS. While HLA-DQA1 risk variants show an association with other CKD aetiologies, PLA2R1 variants are specific to MN.

Healthcare decision-making in end stage renal disease-patient preferences and clinical correlates

Background

Medical decision-making is critical to patient survival and well-being. Patients with end stage renal disease (ESRD) are faced with incrementally complex decision-making throughout their treatment journey. The extent to which patients seek involvement in the decision-making process and factors which influence these in ESRD need to be understood.

Methods

535 ESRD patients were enrolled into the cross-sectional study arm and 30 patients who started dialysis were prospectively evaluated. Patients were enrolled into 3 groups- ‘predialysis’ (group A), ‘in-centre’ haemodialysis (HD) (group B) and self-care HD (93 % at home-group C) from across five tertiary UK renal centres. The Autonomy Preference Index (API) has been employed to study patient preferences for information-seeking (IS) and decision-making (DM). Demographic, psychosocial and neuropsychometric assessments are considered for analyses.

Results

458 complete responses were available. API items have high internal consistency in the study population (Cronbach’s alpha > 0.70). Overall and across individual study groups, the scores for information-seeking and decision-making are significantly different indicating that although patients had a strong preference to be well informed, they were more neutral in their preference to participate in DM (p < 0.05). In the age, education and study group adjusted multiple linear regression analysis, lower age, female gender, marital status; higher API IS scores and white ethnicity background were significant predictors of preference for decision-making. DM scores were subdivided into tertiles to identify variables associated with high (DM > 70: and low DM (≤30) scores. This shows association of higher DM scores with lower age, lower comorbidity index score, higher executive brain function, belonging in the self-caring cohort and being unemployed. In the prospectively studied cohort of predialysis patients, there was no change in decision-making preference scores after commencement of dialysis.

Conclusion

ESRD patients prefer to receive information, but this does not always imply active involvement in decision-making. By understanding modifiable and non-modifiable factors which affect patient preferences for involvement in healthcare decision-making, health professionals may acknowledge the need to accommodate individual patient preferences to the extent determined by the individual patient factors.

Electronic supplementary material

The online version of this article (doi:10.1186/s12882-015-0180-8) contains supplementary material, which is available to authorized users.

A Multicenter Randomized Controlled Trial of Rituximab versus Cyclosporine in the Treatment of Idiopathic Membranous Nephropathy (MENTOR)

BACKGROUND

Idiopathic membranous nephropathy remains the leading cause of nephrotic syndrome in Caucasian adults. Immunosuppressive therapy with cyclosporine (CSA) is often successful in reducing proteinuria, but its use is associated with a high relapse rate. Rituximab, a monoclonal antibody that specifically targets CD20 on the surface of B-cells, is effective in achieving a complete remission of proteinuria in patients with idiopathic membranous nephropathy. However, whether rituximab is as effective as CSA in inducing and maintaining complete or partial remission of proteinuria in these patients is unknown. The membranous nephropathy trial of rituximab (MENTOR) hypothesizes that B-cell targeting with rituximab is non-inferior to CSA in inducing long-term remission of proteinuria.

METHODS AND DESIGN

Patients with idiopathic membranous nephropathy, proteinuria ≥5 g/24 h, and a minimum of 3 months of Angiotensin-II blockade will be randomized into a 12-month treatment period with i.v. rituximab, 1,000 mg (2 infusions, 14 days apart; repeated at 6 months if a substantial reduction in proteinuria (equal to or >25%) is seen at 6 months) or oral CSA 3.5-5 mg/kg/day for 6 months (continued for another 6 months if a substantial reduction in proteinuria (equal to or >25%) is seen at 6 months). The efficacy of treatment will be assessed by the remission status (based on changes in proteinuria) at 24 months from randomization. Patient safety will be assessed via collection of adverse event data and evaluation of pre- and posttreatment laboratory data. At the 6-month post-randomization visit, patients who have been randomized to either CSA or rituximab but who do not have a reduction in proteinuria ≥25% (confirmed on repeat measurements within 2 weeks) will be considered treatment failures and exit the study.

DISCUSSION

This study will test for the first time whether treatment with rituximab is non-inferior to CSA in inducing long-term remission (complete or partial) of proteinuria in patients with idiopathic membranous nephropathy.

Self-cannulation for haemodialysis: patient attributes, clinical correlates and self-cannulation predilection models

BACKGROUND AND OBJECTIVES

With emerging evidence in support of home haemodialysis (HHD), patient factors which determine uptake of the modality need to be better understood. Self-cannulation (SC) is a major step towards enabling self-care 'in-centre' and at home and remains the foremost barrier to its uptake. Human factors governing this aspect of HD practice are poorly understood. The aim of this study is to better understand self-cannulation preferences and factors which define them in end stage renal disease (ESRD).

DESIGN

In this multicentre study, 508 of 535 patients from predialysis (Group A: n = 222), in-centre (Group B: n = 213), and home HD (Group C: n = 100) responded to a questionnaire with 3 self-cannulation questions. Simultaneously, data on clinical, cognitive and psychosocial variables were ascertained. The primary outcome measure was 'perceived ability to self-cannulate AV access'. Predictive models were developed using logistic regression analysis.

RESULTS

36.6% of predialysis patients (A) and 29.1% of the 'in-centre' haemodialysis patients (B) felt able to consider SC for HD. Technical-skills related apprehension was highest in Group B (14.4%) patients. Response to routine venepuncture and the types of SC concerns were significant predictors of perceived ability to self-cannulate. There was no significant difference in concern for pain across the groups. In multivariable regression analysis, age, education level, 3 MS score, hypoalbuminemia in Groups B & C and additionally, attitude to routine phlebotomy and the nature of specific concern for self-cannulation in Groups A, B and C, are significant predictors of SC preference. The unadjusted c-statistics of models 1 (derived from Group A and validated on A) and 2 (derived from B+C and validated on B), are 0.76(95% CI 0.69, 0.83) and 0.80 (95% CI 0.74, 0.87) respectively.

CONCLUSIONS

There is high prevalence of perceived ability to self-cannulate. Modifiable SC concerns exist in ESRD. The use of predictive models to objectively define and target education and training strategies could potentially impact on HD self-management and future uptake of home HD.

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.

Barriers to successful implementation of care in home haemodialysis (BASIC-HHD):1. Study design, methods and rationale

Background

Ten years on from the National Institute of Health and Clinical Excellence’ technology appraisal guideline on haemodialysis in 2002; the clinical community is yet to rise to the challenge of providing home haemodialysis (HHD) to 10-15% of the dialysis cohort. The renal registry report, suggests underutilization of a treatment type that has had a lot of research interest and several publications worldwide on its apparent benefit for both physical and mental health of patients. An understanding of the drivers to introducing and sustaining the modality, from organizational, economic, clinical and patient perspectives is fundamental to realizing the full benefits of the therapy with the potential to provide evidence base for effective care models. Through the BASIC-HHD study, we seek to understand the clinical, patient and carer related psychosocial, economic and organisational determinants of successful uptake and maintenance of home haemodialysis and thereby, engage all major stakeholders in the process.

Design and methods

We have adopted an integrated mixed methodology (convergent, parallel design) for this study. The study arms include a. patient; b. organization; c. carer and d. economic evaluation. The three patient study cohorts (n = 500) include pre-dialysis patients (200), hospital haemodialysis (200) and home haemodialysis patients (100) from geographically distinct NHS sites, across the country and with variable prevalence of home haemodialysis. The pre-dialysis patients will also be prospectively followed up for a period of 12 months from study entry to understand their journey to renal replacement therapy and subsequently, before and after studies will be carried out for a select few who do commence dialysis in the study period. The process will entail quantitative methods and ethnographic interviews of all groups in the study. Data collection will involve clinical and biomarkers, psychosocial quantitative assessments and neuropsychometric tests in patients. Organizational attitudes and dialysis unit practices will be studied together with perceptions of healthcare providers on provision of home HD. Economic evaluation of home and hospital haemodialysis practices will also be undertaken and we will apply scenario ("what … if") analysis using system dynamics modeling to investigate the impact of different policy choices and financial models on dialysis technology adoption, care pathways and costs. Less attention is often given to the patient’s carers who provide informal support, often of a complex nature to patients afflicted by chronic ailments such as end stage kidney disease. Engaging the carers is fundamental to realizing the full benefits of a complex, home-based intervention and a qualitative study of the carers will be undertaken to elicit their fears, concerns and perception of home HD before and after patient’s commencement of the treatment. The data sets will be analysed independently and the findings will be mixed at the stage of interpretation to form a coherent message that will be informing practice in the future.

Discussion

The BASIC-HHD study is designed to assemble pivotal information on dialysis modality choice and uptake, investigating users, care-givers and care delivery processes and study their variation in a multi-layered analytical approach within a single health care system. The study results would define modality specific service and patient pathway redesign.

Study Registration

This study has been reviewed and approved by the Greater Manchester West Health Research Authority National Research Ethics Service (NRES) The study is on the NIHR (CLRN) portfolio.

Reverse iontophoresis of urea in health and chronic kidney disease: a potential diagnostic and monitoring tool?

BACKGROUND

Patients with chronic kidney disease (CKD) need regular monitoring, usually by blood urea and creatinine measurements, needing venepuncture, frequent attendances and a healthcare professional, with significant inconvenience. Noninvasive monitoring will potentially simplify and improve monitoring. We tested the potential of transdermal reverse iontophoresis of urea in patients with CKD and healthy controls.

METHODS

Using a MIC 2(®) Iontophoresis Controller, reverse iontophoresis was applied on the forearm of five healthy subjects (controls) and 18 patients with CKD for 3-5 h. Urea extracted at the cathode was measured and compared with plasma urea.

RESULTS

Reverse iontophoresis at 250 μA was entirely safe for the duration. Cathodal buffer urea linearly correlated with plasma urea after 2 h (r = 0·82, P < 0·0001), to 3·5 h current application (r = 0·89, P = 0·007). The linear equations y = 0·24x + 1 and y = 0·21x + 4·63 predicted plasma urea (y) from cathodal urea after 2 and 3 h, respectively. Cathodal urea concentration in controls was significantly lower than in patients with CKD after a minimum current application of 2 h (P < 0·0001), with the separation between the two groups becoming more apparent with longer application (P = 0·003). A cathodal urea cut-off of 30 μM gave a sensitivity of 83·3% and positive predictive value of 87% CKD. During haemodialysis, the fall in cathodal urea was able to track that of blood urea.

CONCLUSION

Reverse iontophoresis is safe, can potentially discriminate patients with CKD and healthy subjects and is able to track blood urea changes on dialysis. Further development of the technology for routine use can lead to an exciting opportunity for its use in diagnostics and monitoring.

Genetically distinct subsets within ANCA-associated vasculitis

BACKGROUND

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis is a severe condition encompassing two major syndromes: granulomatosis with polyangiitis (formerly known as Wegener's granulomatosis) and microscopic polyangiitis. Its cause is unknown, and there is debate about whether it is a single disease entity and what role ANCA plays in its pathogenesis. We investigated its genetic basis.

METHODS

A genomewide association study was performed in a discovery cohort of 1233 U.K. patients with ANCA-associated vasculitis and 5884 controls and was replicated in 1454 Northern European case patients and 1666 controls. Quality control, population stratification, and statistical analyses were performed according to standard criteria.

RESULTS

We found both major-histocompatibility-complex (MHC) and non-MHC associations with ANCA-associated vasculitis and also that granulomatosis with polyangiitis and microscopic polyangiitis were genetically distinct. The strongest genetic associations were with the antigenic specificity of ANCA, not with the clinical syndrome. Anti-proteinase 3 ANCA was associated with HLA-DP and the genes encoding α(1)-antitrypsin (SERPINA1) and proteinase 3 (PRTN3) (P=6.2×10(-89), P=5.6×10(-12,) and P=2.6×10(-7), respectively). Anti-myeloperoxidase ANCA was associated with HLA-DQ (P=2.1×10(-8)).

CONCLUSIONS

This study confirms that the pathogenesis of ANCA-associated vasculitis has a genetic component, shows genetic distinctions between granulomatosis with polyangiitis and microscopic polyangiitis that are associated with ANCA specificity, and suggests that the response against the autoantigen proteinase 3 is a central pathogenic feature of proteinase 3 ANCA-associated vasculitis. These data provide preliminary support for the concept that proteinase 3 ANCA-associated vasculitis and myeloperoxidase ANCA-associated vasculitis are distinct autoimmune syndromes. (Funded by the British Heart Foundation and others.).

Transforming growth factor β-induced peritoneal fibrosis is mouse strain dependent

BACKGROUND

Encapsulating peritoneal sclerosis (EPS) is a rare but devastating complication of peritoneal dialysis. The etiology is unclear, but genetic predisposition may be a contributing factor. We used adenovirus-mediated gene transfer of transforming growth factor (TGF) β1 to the peritoneum in four genetically distinct laboratory mouse strains to assess differences in fibrogenic response.

METHODS

Mice from four genetic backgrounds (C57BL/6J, DBA/2J, C3H/HeJ and SJL/J) received an intraperitoneal injection of an adenovirus expressing TGFβ1 (AdTGFβ1) or control adenovirus (AdDL) and were assessed 4 and 10 days after infection. Submesothelial thickening, angiogenesis and gene expression were quantified from peritoneal tissue. Protein was extracted from omental tissue and assessed for collagen, E-cadherin and TGFβ signaling pathway proteins.

RESULTS

There was a graded response among the mouse strains to the peritoneal overexpression of TGFβ1. TGFβ1 induced a significant fibrogenic response in the C57BL/6J mice, whereas the SJL/J mice were resistant. The DBA/2J and the C3H/HeJ mice had intermediate responses. A similar graded response was seen in collagen protein levels in the omental tissue and in fibrosis-associated gene expression. TGFβ type 1 receptor and SMAD signaling pathways appeared to be intact in all the mouse strains.

CONCLUSIONS

There were significant differences in mouse strain susceptibility to peritoneal fibrosis, suggesting that genetic factors may play a role in the development of peritoneal fibrosis and possibly EPS. As early TGFβ1 signaling mechanisms appear to be intact, we hypothesize that fibrosis resistance in the SJL/J mice lies further down the wound-healing cascade or in an alternate, non-SMAD pathway.

Proof-of-principle study to detect metabolic changes in peritoneal dialysis effluent in patients who develop encapsulating peritoneal sclerosis

BACKGROUND

Prolonged peritoneal dialysis (PD) therapy can result in the development of encapsulating peritoneal sclerosis (EPS), characterized by extensive sclerosis of the peritoneum with bowel adhesions often causing obstruction.

METHODS

As a proof-of-principle study, holistic profiling of endogenous metabolites has been applied in a prospective collection of PD effluent collected in multiple UK renal centres over 6 years in order to investigate metabolic differences in PD effluent between PD therapy patients who later developed clinically defined EPS (n = 11) and controls, who were matched for PD vintage, age and gender (n = 11).

RESULTS

'Fit-for-purpose' analytical methods employing gas chromatography-mass spectrometry (MS), direct injection MS and quality control samples were developed and validated. These methods were applied in a proof-of-principle study to define metabolic differences in PD effluent related to subsequent development of EPS. Changes in amino acids, amines and derivatives, short-chain fatty acids and derivatives and sugars were observed prior to EPS developing, and changes in the metabolomic profiles could be detected.

CONCLUSION

There is potential for applying metabolic profiles to identify patients at risk of developing EPS although long-term prospective studies with larger patient cohorts are required.