Histologic and Clinical Factors Associated with Kidney Outcomes in IgA Vasculitis Nephritis

BACKGROUND

Nephritis is a common manifestation of IgA vasculitis and is morphologically indistinguishable from IgA nephropathy. While MEST-C scores are predictive of kidney outcomes in IgA nephropathy, their value in IgA vasculitis nephritis has not been investigated in large multiethnic cohorts.

METHODS

Biopsies from 262 children and 99 adults with IgA vasculitis nephritis ( N =361) from 23 centers in North America, Europe, and Asia were independently scored by three pathologists. MEST-C scores were assessed for correlation with eGFR/proteinuria at biopsy. Because most patients ( N =309, 86%) received immunosuppression, risk factors for outcomes were evaluated in this group using latent class mixed models to identify classes of eGFR trajectories over a median follow-up of 2.7 years (interquartile range, 1.2-5.1). Clinical and histologic parameters associated with each class were determined using logistic regression.

RESULTS

M, E, T, and C scores were correlated with either eGFR or proteinuria at biopsy. Two classes were identified by latent class mixed model, one with initial improvement in eGFR followed by a late decline (class 1, N =91) and another with stable eGFR (class 2, N =218). Class 1 was associated with a higher risk of an established kidney outcome (time to ≥30% decline in eGFR or kidney failure; hazard ratio, 5.84; 95% confidence interval, 2.37 to 14.4). Among MEST-C scores, only E1 was associated with class 1 by multivariable analysis. Other factors associated with class 1 were age 18 years and younger, male sex, lower eGFR at biopsy, and extrarenal noncutaneous disease. Fibrous crescents without active changes were associated with class 2.

CONCLUSIONS

Kidney outcome in patients with biopsied IgA vasculitis nephritis treated with immunosuppression was determined by clinical risk factors and endocapillary hypercellularity (E1) and fibrous crescents, which are features that are not part of the International Study of Diseases of Children classification.

Oral Nutritional Supplement Prescription and Patient-Reported Symptom Burden Among Patients With Late-Stage Non-Dialysis Chronic Kidney Disease

Background

Malnutrition and protein-energy wasting (PEW) are nutritional complications of advanced chronic kidney disease (CKD) that contribute to morbidity, mortality, and decreased quality of life. No previous studies have assessed the effect of oral nutritional supplements (ONSs) on patient-reported symptom burden among patients with non-dialysis CKD (CKD-ND) who have or are at risk of malnutrition/PEW.

Objective

The objective of this study was (1) to quantify the associations between baseline nutritional parameters and patient-reported symptom scores for wellbeing, tiredness, nausea, and appetite and (2) to compare the change in symptom scores among patients prescribed ONS with patients who did not receive ONS in a propensity-score-matched analysis.

Design

This study conducted observational cohort analysis using provincial registry data.

Setting

This study was done in multidisciplinary CKD clinics in British Columbia.

Patients

Adult patients >18 years of age with CKD-ND entering multidisciplinary CKD clinics between January 1, 2010-July 31, 2019 who had at least 2 Edmonton Symptom Assessment System Revised: Renal (ESASr:Renal) assessments.

Measurements

The measurements include nutrition-related parameters such as body mass index (BMI), serum albumin, serum phosphate, serum bicarbonate, neutrophil-to-lymphocyte ratio (NLR), and ESASr:Renal scores (overall and subscores for wellbeing, tiredness, nausea, and appetite).

Methods

Multivariable linear regression was applied to assess associations between nutritional parameters and ESASr:Renal scores. Propensity-score matching using the greedy method was used to match patients prescribed ONS with those not prescribed ONS using multiple demographic, comorbidity, health care utilization, and temporal factors. Linear regression was used to assess the association between first ONS prescription and change in ESASr:Renal overall score and subscores for wellbeing, tiredness, nausea, and appetite.

Results

Of total, 2076 patients were included. Higher baseline serum albumin was associated with lower overall ESASr:Renal score (-0.20, 95% confidence interval [CI] = -0.40 to -0.01 per 1 g/L increase in albumin), lower subscores for tiredness (-0.04, 95% CI = -0.07 to -0.01), nausea (-0.03, 95% CI = -0.04 to -0.01), and appetite (-0.03, 95% CI = -0.06 to -0.01). Higher BMI was associated with higher overall ESASr:Renal score (0.32, 95% CI = 0.16 to 0.48 per 1 kg/m2 increase in BMI), higher symptom subscores for wellbeing (0.02, 95% CI = 0.00 to 0.04) and tiredness (0.05, 95% CI = 0.02 to 0.07). Higher baseline NLR was associated with higher overall score (0.21, 95% CI = 0.03 to 0.39 per 1 unit increase in NLR), higher symptom subscores for wellbeing (0.03, 95% CI = 0.01 to 0.05) and nausea (0.03, 95% CI = 0.02 to 0.05). In the propensity-score-matched analysis, there were no statistically significant associations between ONS prescription and change in overall ESASr:Renal (beta coefficient for change in ESASr:Renal = 0.17, 95% CI = -2.64 to 2.99) or for subscores for appetite, tiredness, nausea, and wellbeing.

Limitations

Possible residual confounding. The ESASr:Renal assessments were obtained routinely only in patients with G5 CKD-ND and/or experiencing significant CKD-related symptoms.

Conclusions

This exploratory observational analysis of patients with advanced non-dialysis CKD demonstrated BMI, serum albumin, and NLR were modestly associated with patient-reported symptoms, but we did not observe an association between ONS use and change in ESASr:Renal scores.

Kidney Failure Risk Equation in vascular access planning: a population-based study supporting value in decision making

Background

The Kidney Failure Risk Equation (KFRE) can play a better role in vascular access (VA) planning in patients with chronic kidney disease (CKD) requiring hemodialysis (HD). We described the VA creation and utilization pattern under existing estimated glomerular filtration rate (eGFR)-based referral, and investigated the utility of KFRE score as an adjunct variable in VA planning.

Methods

Patients with CKD aged ≥18 years with eGFR <20 mL/min/1.73 m2 who chose HD as dialysis modality from January 2010 to August 2020 were included from a population-based database in British Columbia, Canada. Modality selection date was the index date. Exposures were categorized as (i) current eGFR-based referral, (ii) eGFR-based referral plus KRFE 2-year risk score on index date (KFRE-2) >40% and (iii) eGFR-based referral plus KFRE-2 ≤40%. We estimated the proportion of patients who started HD on arteriovenous fistula/graft (AVF/G) within 2 years, indicating timely pre-emptive creation, and the proportion of patients in whom AVF/G was created but did not start HD within 2 years, indicating too-early creation.

Results

Study included 2581 patients, median age 71 years, 60% male. Overall, 1562(61%) started HD and 276 (11%) experienced death before HD initiation within 2 years. Compared with current referral, the proportion of patients who started HD on AVF/G was significantly higher when KFRE-2 was considered in addition to current referral (49% vs 58%, P-value <.001). Adjunct KFRE-2 significantly reduced too-early creation (31% vs 18%, P-value <.001).

Conclusions

KFRE in addition to existing eGFR-based referral for VA creation has the potential to improve VA resource utilization by ensuring more patients start HD on AVF/G and may minimize too-early/unnecessary creation. Prospective research is necessary to validate these findings.

Humoral Response Following 3 Doses of mRNA COVID-19 Vaccines in Patients With Non-Dialysis-Dependent CKD: An Observational Study

Background

Chronic kidney disease (CKD) is associated with a lower serologic response to vaccination compared to the general population. There is limited information regarding the serologic response to coronavirus disease 2019 (COVID-19) vaccination in the non-dialysis-dependent CKD (NDD-CKD) population, particularly after the third dose and whether this response varies by estimated glomerular filtration rate (eGFR).

Methods

The NDD-CKD (G1-G5) patients who received 3 doses of mRNA COVID-19 vaccines were recruited from renal clinics within British Columbia and Ontario, Canada. Between August 27, 2021, and November 30, 2022, blood samples were collected serially for serological testing every 3 months within a 9-month follow-up period. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) anti-spike, anti-receptor binding domain (RBD), and anti-nucleocapsid protein (NP) levels were determined by enzyme-linked immunosorbent assay (ELISA).

Results

Among 285 NDD-CKD patients, the median age was 67 (interquartile range [IQR], 52-77) years, 58% were men, 48% received BNT162b2 as their third dose, 22% were on immunosuppressive treatment, and COVID-19 infection by anti-NP seropositivity was observed in 37 of 285 (13%) patients. Following the third dose, anti-spike and anti-RBD levels peaked at 2 months, with geometric mean levels at 1131 and 1672 binding antibody units per milliliter (BAU/mL), respectively, and seropositivity rates above 93% and 85%, respectively, over the 9-month follow-up period. There was no association between eGFR or urine albumin-creatinine ratio (ACR) with mounting a robust antibody response or in antibody levels over time. The NDD-CKD patients on immunosuppressive treatment were less likely to mount a robust anti-spike response in univariable (odds ratio [OR] 0.43, 95% confidence interval [CI]: 0.20, 0.93) and multivariable (OR 0.52, 95% CI: 0.25, 1.10) analyses. An interaction between age, immunoglobulin G (IgG) antibody levels, and time was observed in both unadjusted (anti-spike: P = .005; anti-RBD: P = .03) and adjusted (anti-spike: P = .004; anti-RBD: P = .03) models, with older individuals having a more pronounced decline in antibody levels over time.

Conclusion

Most NDD-CKD patients were seropositive for anti-spike and anti-RBD after 3 doses of mRNA COVID-19 vaccines and we did not observe any differences in the antibody response by eGFR.

Regional Variation in Hemoglobin Distribution Among Individuals With CKD: the ISN International Network of CKD Cohorts

Introduction

Despite recognized geographic and sex-based differences in hemoglobin in the general population, these factors are typically ignored in patients with chronic kidney disease (CKD) in whom a single therapeutic range for hemoglobin is recommended. We sought to compare the distribution of hemoglobin across international nondialysis CKD populations and evaluate predictors of hemoglobin.

Methods

In this cross-sectional study, hemoglobin distribution was evaluated in each cohort overall and stratified by sex and estimated glomerular filtration rate (eGFR). Relationships between candidate predictors and hemoglobin were assessed from linear regression models in each cohort. Estimates were subsequently pooled in a random effects model.

Results

A total of 58,613 participants from 21 adult cohorts (median eGFR range of 17-49 ml/min) and 3 pediatric cohorts (median eGFR range of 26-45 ml/min) were included with broad geographic representation. Hemoglobin values varied substantially among the cohorts, overall and within eGFR categories, with particularly low mean hemoglobin observed in women from Asian and African cohorts. Across the eGFR range, women had a lower hemoglobin compared to men, even at an eGFR of 15 ml/min (mean difference 5.3 g/l, 95% confidence interval [CI] 3.7-6.9). Lower eGFR, female sex, older age, lower body mass index, and diabetic kidney disease were all independent predictors of a lower hemoglobin value; however, this only explained a minority of variance (R2 7%-44% across cohorts).

Conclusion

There are substantial regional differences in hemoglobin distribution among individuals with CKD, and the majority of variance is unexplained by demographics, eGFR, or comorbidities. These findings call for a renewed interest in improving our understanding of hemoglobin determinants in specific CKD populations.

COVID-19 Vaccine Effectiveness Among Patients With Maintenance Dialysis; Observations From Population Level Cohort Studies in 2 Large Canadian Provinces

Background

It was unknown if the effectiveness of COVID-19 vaccines could vary between regions.

Objective

To explore key differences in COVID-19 pandemics in British Columbia (BC) and Ontario (ON) and to investigate if the vaccine effectiveness (VE) among maintenance dialysis population could vary between these 2 provinces.

Study Design

Retrospective cohort.

Setting and Patients

This retrospective cohort study included patients from population-level registry in BC who were on maintenance dialysis from December 14, 2020, to December 31, 2021. The COVID-19 VE among BC patients were compared to the previously published VE among similar patient population in ON. Two-sample t-test for unpaired data were used to investigate if the VE estimates from BC and ON were statistically significantly different.

Exposure

Exposure to COVID-19 vaccines (BNT162b2, ChAdOx1nCoV-19, mRNA-1273) was modeled in a time-dependent fashion.

Outcome

Reverse transcription polymerase chain reaction (RT-PCR) confirmed COVID-19 infection and related severe outcome defined by hospitalization or death.

Analytical Approach

Time-dependent Cox regression analysis.

Results

This study using BC data included 4284 patients. Median age was 70 years and 61% was male. Median follow-up time was 382 days. 164 patients developed COVID-19 infection. The ON study by Oliver et al included 13 759 patients with a mean age of 68 years. 61% of the study sample was male. Median follow-up time for patients in the ON study was 102 days. A total of 663 patients developed COVID-19 infection. During the overlapped study periods, BC had 1 pandemic wave compared to 2 in Ontario with substantially higher infection rates. Vaccination timing and roll out among the study population were substantially different. Median time between first and second dose was 77 days (interquartile range [IQR] 66-91) in BC compared to 39 days (IQR = 28-56) in Ontario. Distribution of COVID-19 variants during the study period appeared to be similar. In BC, compared to pre-vaccination person-time, risk of developing COVID-19 infection was 64% (aHR [95% CI] 0.36 [0.21, 0.63]), 80% (0.20 [0.12, 0.35]) and 87% (0.13 [0.06, 0.29]) less when exposed to 1 dose, 2 doses, and 3 doses, respectively. In contrast, risk reduction among Ontario patients was 41% (0.59 [0.46, 0.76]) and 69% (0.31 [0.22, 0.42]) for 1 dose and 2 doses, respectively (patients did not receive the third dose by study end date of June 30, 2021). VE against COVID-19 infection in BC and ON was not statistically significantly different, the P values for exposure to 1 dose and 2 doses comparisons were 0.103 and 0.163, respectively. Similarly, in BC, risk of developing COVID-19-related hospitalization or death were 54% (0.46 [0.24, 0.90]), 75% (0.25 [0.13, 0.48]) and 86% (0.14 [0.06, 0.34]) less for 1 dose, 2 doses, and 3 doses, respectively. Interestingly, exposure to second dose appeared to provide better protection against severe outcomes in Ontario versus BC, risk reduction was 83% (aHR = 0.17, 95% CI [0.10, 0.30]) and 75% (aHR = 0.25, 95% CI [0.13, 0.48]), respectively. However, the adjusted hazard ratios were not statistically significantly different between BC and ON, the P values were 0.676 and 0.369 for exposure to 1 dose and 2 doses, respectively.

Limitations

Infection rate, variant distribution, and vaccination strategies were compared using publicly available data. VE estimates were compared from 2 independent cohort studies from 2 provinces without patient-level data sharing.

Conclusions

Health Canada approved COVID-19 vaccines were highly effective among patients with maintenance dialysis from BC and ON. Although there appeared to be between province differences in pandemic waves and vaccination strategies, the VE against COVID-19 infection as well as related severe outcome appeared to be not statistically significantly different. A nationally representative VE could be estimated using pooled data from multiple regions.

Evaluation and outcomes of a 5-year assisted peritoneal dialysis program

BACKGROUND

In 2016, Peritoneal Dialysis Assist (PDA) was implemented in British Columbia, Canada, as a pilot program to allow patients with physical, cognitive and social impairments to access an independent dialysis modality. This is a presentation of the usage and 5-year clinical outcomes of our provincial assisted peritoneal dialysis (PD) program.

METHODS

Patients who utilised long-term or respite PDA services in British Columbia, Canada, from 2016 to 2021 were included in this program evaluation. Incident and prevalent patient numbers were characterised annually as well as indications for PDA and patient demographics both annually and over time. Outcomes of interest included death, transfer to haemodialysis, transplantation and cessation of the PDA program but retention on PD.

RESULTS

Three hundred twenty-two total patients received services through the PDA program. The percentage of PD patients supported by long-term PDA service has grown to 11.2% in the most recent year. Patients spend a median of 13.6 (95% CI: 11.0, 16.1) months on long-term PDA, prolonging overall patient duration on PD by a little over a year. Of the patients who exited the long-term PDA program, 73 (37.4%) were able to utilise the service until they died.

CONCLUSION

PDA is an accessible, patient-centric service with clear and standardised referral criteria. Through the implementation of a local PDA program, patients have accessed PD and may have extended their PD life span, through avoidance of in-centre haemodialysis, by over 13 months during this 5-year study period. A significant proportion of patients on long-term PDA were able to use their preferred kidney replacement modality at home until they reached end of life.

A Population-Based Analysis of the Risk of Glomerular Disease Relapse after COVID-19 Vaccination

BACKGROUND

Although case reports have described relapses of glomerular disease after COVID-19 vaccination, evidence of a true association is lacking. In this population-level analysis, we sought to determine relative and absolute risks of glomerular disease relapse after COVID-19 vaccination.

METHODS

In this retrospective population-level cohort study, we used a centralized clinical and pathology registry (2000-2020) to identify 1105 adult patients in British Columbia, Canada, with biopsy-proven glomerular disease that was stable on December 14, 2020 (when COVID-19 vaccines first became available). The primary outcome was disease relapse, on the basis of changes in kidney function, proteinuria, or both. Vaccination was modeled as a 30-day time-varying exposure in extended Cox regression models, stratified on disease type.

RESULTS

During 281 days of follow-up, 134 (12.1%) patients experienced a relapse. Although a first vaccine dose was not associated with relapse risk (hazard ratio [HR]=0.67; 95% confidence interval [95% CI], 0.33 to 1.36), exposure to a second or third dose was associated with a two-fold risk of relapse (HR=2.23; 95% CI, 1.06 to 4.71). The pattern of relative risk was similar across glomerular diseases. The absolute increase in 30-day relapse risk associated with a second or third vaccine dose varied from 1%-2% in ANCA-related glomerulonephritis, minimal change disease, membranous nephropathy, or FSGS to 3%-5% in IgA nephropathy or lupus nephritis. Among 24 patients experiencing a vaccine-associated relapse, 4 (17%) had a change in immunosuppression, and none required a biopsy.

CONCLUSIONS

In a population-level cohort of patients with glomerular disease, a second or third dose of COVID-19 vaccine was associated with higher relative risk but low absolute increased risk of relapse.

A Pilot Study to Predict Risk of IgA Nephropathy Progression Based on miR-204 Expression

Introduction

Immunoglobulin (Ig)A nephropathy (IgAN) is the most frequently diagnosed primary glomerulonephritis worldwide. Despite the common diagnostic feature of mesangial IgA-containing immune complex deposition, the clinical course of the disease is extremely variable, with 30% of patients developing end-stage kidney disease within 20 years of diagnosis. Therefore, identifying which patients are likely to progress is paramount.

Results

In this pilot study, we found that urinary exosomal miR-204 expression was significantly reduced in IgAN compared with healthy subjects. However, there was no difference in miR-204 expression between IgAN and non-IgAN chronic kidney disease controls. Analysis of miR-204 expression in kidney biopsy cores by next-generation sequencing followed by quantitative polymerase chain reaction validation in independent cohorts demonstrated that expression of miR-204 was significantly lower in IgAN compared with thin-membrane nephropathy but not compared with membranous nephropathy. Patients with IgAN at high risk of future progression had significantly lower expression of miR-204 than those at low risk of progression. Cortical localization indicated that miR-204 was preferentially expressed in the interstitium compared with glomeruli in IgAN nonprogressors and that this distribution was lost in IgAN progressors. Receiver operating characteristic curve analysis between the 2 IgAN cohorts revealed an area under the curve of 0.82. In addition, miR-204 expression correlated with known clinicopathological prognostic risk factors. Importantly, incorporating miR-204 into the International IgAN risk prediction tool improved the diagnostic power of the algorithm to predict risk of progression.

Conclusion

Additional large-scale studies are now needed to validate the additive value of miR-204 in improving risk prediction in IgAN and more broadly in chronic kidney disease.

Quantifying Missed Opportunities for Recruitment to Home Dialysis Therapies

Background:

Despite the recognized benefits of home therapies for patients and the health care system, most individuals with kidney failure in Canada continue to be initiated on in-center hemodialysis. To optimize recruitment to home therapies, there is a need for programs to better understand the extent to which potential candidates are not successfully initiated on these therapies.

Objective:

We aimed to quantify missed opportunities to recruit patients to home therapies and explore where in the modality selection process this occurs.

Design:

Retrospective observational study.

Setting:

British Columbia, Canada.

Patients:

All patients aged >18 years who started chronic dialysis in British Columbia between January 01, 2015, and December 31, 2017. The sample was further restricted to include patients who received at least 3 months of predialysis care. All patients were followed for a minimum of 12 months from the start of dialysis to capture any transition to home therapies.

Methods:

Cases were defined as a “missed opportunity” if a patient had chosen a home therapy, or remained undecided about their preferred modality, and ultimately received in-center hemodialysis as their destination therapy. These cases were assessed for: (1) documentation of a contraindication to home therapies; and (2) the type of dialysis education received. Differences in characteristics among patients classified as an appropriate outcome or a missed opportunity were examined using Wilcoxon rank-sum test or χ² test, as appropriate.

Results:

Of the 1845 patients who started chronic dialysis during the study period, 635 (34%) were initiated on a home therapy. A total of 320 (17.3%) missed opportunities were identified, with 165 (8.9%) having initially chosen a home therapy and 155 (8.4%) being undecided about their preferred modality. Compared with patients who chose and initiated or transitioned to a home therapy, those identified as a missed opportunity tended to be older with a higher prevalence of cardiovascular disease. A contraindication to both peritoneal dialysis and home hemodialysis was documented in 8 “missed opportunity” patients. General modality orientation was provided to most (71%) patients who had initially chosen a home therapy but who ultimately received in-center hemodialysis. These patients received less home therapy–specific education compared with patients who chose and subsequently started a home therapy (20% vs 35%, P < .001).

Limitations:

Contraindications to home therapies were potentially under-ascertained, and the nature of contraindications was not systematically captured.

Conclusions:

Even within a mature home therapy program, we discovered a substantial number of missed opportunities to recruit patients to home therapies. Better characterization of modality contraindications and enhanced education that is specific to home therapies may be of benefit. Mapping the recruitment pathway in this way can define the magnitude of missed opportunities and identify areas that could be optimized. This is to be encouraged, as even small incremental improvements in the uptake of home therapies could lead to better patient outcomes and contribute to significant cost savings for the health care system.

Trial Registration:

Not applicable as this was a qualitative study.

Maintaining the Uptake of Peritoneal Dialysis During the COVID-19 Pandemic: A Research Letter

BACKGROUND

Due to inherent challenges in maintaining physical distancing in hemodialysis units, the Canadian Society of Nephrology has recommended peritoneal dialysis as the preferred modality for patients requiring maintenance dialysis during the coronavirus disease 19 (COVID-19) pandemic. However, pursuing peritoneal dialysis is not without risk due to the requirement for in-person contact during catheter insertion and training, and there is a paucity of data regarding the experience of peritoneal dialysis during the early phases of the pandemic.

OBJECTIVE

To examine the incidence and outcomes of peritoneal dialysis between March 17 and June 01, 2020 compared to the same time period in preceding years.

DESIGN

Retrospective observational study.

SETTING

British Columbia, Canada. After the pandemic was declared on March 17, 2020, patients continued to be trained in peritoneal dialysis. In an effort to limit time spent in hospital, patients were preferentially trained in continuous ambulatory peritoneal dialysis, training times were truncated for some patients, and peritoneal dialysis catheters were inserted by a physician at the bedside whenever feasible.

PATIENTS

All patients aged >18 years who started chronic maintenance dialysis during the period March 17 to June 01 in the years 2018 to 2020 inclusive. The time period was extended to include the years 2010 to 2020 inclusive to evaluate longer term trends in dialysis incidence.

MEASUREMENTS

A provincial clinical information system was used to capture the date of commencing dialysis, dialysis modality, and complications including peritonitis. Overall uptake of peritoneal dialysis included new starts and transitions to peritoneal dialysis from in-center hemodialysis during the observation period.

METHODS

The incidence of dialysis during the specified time period, overall and by modality, was calculated per million population using census figures for the population at risk. Patients were followed for a minimum of 30 days from the start of peritoneal dialysis to capture episodes of peritonitis and COVID-19.

RESULTS

A total of 211 patients started maintenance dialysis between March 17 and June 01, 2020. The incidence dialysis rate (41.3 per million population) was lower than that expected based on the 10-year trend from 2010 to 2019 inclusive (expected rate 45.7 per million population, 95% confidence interval 41.7 to 50.1). A total of 93 patients started peritoneal dialysis, including 32 patients who transitioned from in-center hemodialysis, contributing to a higher overall uptake of peritoneal dialysis compared to preceding years. The incidence rate for peritoneal dialysis of 18.2 per million population was higher than that expected (16.3 per million population, 95% confidence interval 14.0 to 19.0). Half of patients (48%) underwent a bedside peritoneal dialysis catheter insertion by a physician. During 30 days of follow-up, 2 (2.2%) patients experienced peritonitis and no patients were diagnosed with COVID-19.

LIMITATIONS

Results are short term and generalizable only to regions with similarly low community rates of transmission of severe acute respiratory syndrome coronavirus 2.

CONCLUSIONS

These preliminary findings indicate that peritoneal dialysis can be safely started and perhaps expanded as a means of mitigating the anticipated surge in in-center hemodialysis during the COVID-19 pandemic. Important contributors to the uptake of peritoneal dialysis in British Columbia were bedside catheter insertions and expediting transitions from in-center hemodialysis to peritoneal dialysis.

Differential expression of microRNA miR-150-5p in IgA nephropathy as a potential mediator and marker of disease progression

Understanding why certain patients with IgA nephropathy progress to kidney failure while others maintain normal kidney function remains a major unanswered question. To help answer this, we performed miRNome profiling by next generation sequencing of kidney biopsies in order to identify microRNAs specifically associated with the risk of IgA nephropathy progression. Following sequencing and validation in independent cohorts, four microRNAs (-150-5p, -155-5p, -146b-5p, -135a-5p) were found to be differentially expressed in IgA nephropathy progressors compared to non-progressors, and patients with thin membrane nephropathy, lupus nephritis and membranous nephropathy, and correlated with estimated glomerular filtration rate, proteinuria, and the Oxford MEST-C scores (five histological features that are independent predictors of clinical outcome). Each individual microRNA increased the discrimination score of the International IgAN Prediction Tool, although due to the small number of samples the results did not reach statistical significance. miR-150-5p exhibited the largest amplitude of expression between cohorts and displayed the best discrimination between IgA nephropathy progressors and non-progressors by receiver operating curve analysis (AUC: 0.8). However, expression was similarly upregulated in kidneys with established fibrosis and low estimated glomerular filtration rates at the time of biopsy. Consistent with a more generic role in kidney fibrosis, in situ hybridization revealed that miR-150-5p was found in lymphoid infiltrates, and areas of proliferation and fibrosis consistent with the known drivers of progression. Thus, miR-150-5p may be a potential functional mediator of kidney fibrosis that may add value in predicting risk of progression in IgA nephropathy and other kidney diseases.

Updating the International IgA Nephropathy Prediction Tool for use in children

Although IgA nephropathy (IgAN) is a common cause of glomerulonephritis in children, the absence of a method to predict disease progression limits personalized risk-based treatment decisions. The adult International IgAN Prediction Tool comprises two validated Cox survival models that predict a 50% decline in estimated glomerular filtration rate (eGFR) or end stage kidney disease (ESKD) using clinical risk factors and Oxford MEST histology scores. Here, we updated the Prediction Tool for use in children using a multiethnic international cohort of 1,060 children with IgAN followed into adulthood. The updated pediatric Prediction Tool had better model fit than the original adult tool with lower Akaike Information Criterion, higher R²_D and similar C-statistics. However, calibration showed very poor agreement between predicted and observed risks likely due to the observed disease trajectory in children. Therefore, the Tool was updated using a secondary outcome of a 30% reduction in eGFR or ESKD, resulting in better R²_D (30.3%/22.2%) and similar C-statistics (0.74/0.68) compared to the adult tool but with good calibration. The trajectory of eGFR over time in children differed from adults being highly non-linear with an increase until 18 years old followed by a linear decline similar to that of adults. A higher predicted risk was associated with a smaller increase in eGFR followed by a more rapid decline, suggesting that children at risk of a 30% decrease in eGFR will eventually experience a larger 50% decrease in eGFR when followed into adulthood. As such, these two outcomes are analogous between pediatric and adult Prediction Tools. Thus, our pediatric Prediction Tool can accurately predict the risk of a 30% decline in eGFR or ESKD in children with IgAN.

External Validation of International Risk-Prediction Models of IgA Nephropathy in an Asian-Caucasian Cohort

Introduction

Two prediction models for IgA nephropathy (IgAN) using clinical variables and the Oxford MEST scores were developed and validated in 2 multiethnic cohorts. Additional external validation is required.

Methods

Biopsy-proven Chinese and Argentinian patients with IgAN were included. The primary outcome was defined as a 50% decline in estimated glomerular filtration rate (eGFR) or end-stage renal disease. C-statistics and stratified analyses were used for model discrimination, coefficient of determination (R²_D) for model fit, and calibration plots for model calibration. Baseline survival function was also evaluated.

Results

A total of 1275 patients were enrolled, with a mean age of 34 (interquartile range: 27–42) years, 50% of whom (638 of 1275) were men. Use of renin-angiotensin system blockers was higher than in previously reported cohorts, whereas other variables were comparable. The C-statistic of the models was 0.81, and R²_D was higher than reported. Survival curves in the subgroups (<16th, ∼16th to <50th, ∼50th to <84th, and ≥84th percentiles of linear predictor) were well separated. Most of the predictor variables, including hazard ratio, predicted 5-year risk, and eGFR decline slope, were worse with risk increasing. The baseline survival function was comparable in our cohort and the reported cohorts. The calibration was acceptable for the full model without race. However, the risk probability over 3 years was overestimated in the full model with race included.

Conclusion

The prediction models showed good performance on personalized risk assessment, which may be used as drug-specific, precision-medicine approaches to treatment decisionmaking.

Improving treatment decisions using personalized risk assessment from the International IgA Nephropathy Prediction Tool

Immunosuppression in IgA nephropathy (IgAN) should be reserved for patients at high-risk of disease progression, which KDIGO guidelines determine based solely on proteinuria 1g or more/day. To investigate if treatment decisions can be more accurately accomplished using individualized risk from the International IgAN Prediction Tool, we simulated allocation of a hypothetical immunosuppression therapy in an international cohort of adults with IgAN. Two decision rules for treatment were applied based on proteinuria of 1g or more/day or predicted risk from the Prediction Tool above a threshold probability. An appropriate decision was defined as immunosuppression allocated to patients experiencing the primary outcome (50% decline in eGFR or ESKD) and withheld otherwise. The net benefit and net reduction in treatment are the proportion of patients appropriately allocated to receive or withhold immunosuppression, adjusted for the harm from inappropriate decisions, calculated for all threshold probabilities from 0-100%. Of 3299 patients followed for 5.1 years, 522 (15.8%) experienced the primary outcome. Treatment allocation based solely on proteinuria of 1g or more/day had a negative net benefit (was harmful) because immunosuppression was increasingly allocated to patients without progressive disease. Compared to using proteinuria, treatment allocation using the Prediction Tool had a larger net benefit up to 23.4% (95% confidence interval 21.5-25.2%) and a larger net reduction in treatment up to 35.1% (32.3-37.8%). Thus, allocation of immunosuppression to high-risk patients with IgAN can be substantially improved using the Prediction Tool compared to using proteinuria.

Glomerular Filtration Rate-Specific Cutoffs Can Refine the Prognostic Value of Circulating Cardiac Biomarkers in Advanced Chronic Kidney Disease

BACKGROUND

Using standard cutoffs derived from healthy adults, high-sensitivity cardiac troponin T (hs-cTnT) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) are frequently elevated in patients with reduced glomerular filtration rate (GFR), with unclear implications. We sought to compare GFR-specific cutoffs of each biomarker with standard cutoffs for discrimination of cardiovascular risk in asymptomatic patients with chronic kidney disease.

METHODS

We investigated a prospective cohort of 1956 participants with median GFR of 27 mL/min/1.73 m². Cox proportional hazards models were used to examine the association between each biomarker and first adjudicated cardiovascular event (unstable angina, myocardial infarction, heart failure, stroke, cardiovascular death). We used an outcome-based approach to identify optimal risk-based cutoffs for each biomarker within GFR strata (< 20, 20-29, 30-44 mL/min/1.73 m²). We evaluated the added prognostic value of each biomarker to a multivariable base model, comparing GFR-specific with standard cutoffs.

RESULTS

Hs-cTnT and NT-proBNP were elevated in 76% and 82% of participants, respectively. A total of 401 events were recorded during 6772 person-years at risk. Both biomarkers were independent predictors of cardiovascular events. Optimal cutoffs for each biomarker were higher than standard thresholds, being highest at GFR values < 20 mL/min/1.73 m². Addition of hs-cTnT to the base model using GFR-specific cutoffs significantly improved reclassification for events (52%) and nonevents (21%). Similar findings were observed for NT-proBNP. In contrast, use of standard cutoffs failed to reclassify patients who had no event as lower risk.

CONCLUSIONS

Among asymptomatic patients with advanced chronic kidney disease, optimal cutoffs for hs-cTnT and NT-proBNP differed according to GFR level and outperformed standard cutoffs for discrimination of cardiovascular risk.

Evaluating a New International Risk-Prediction Tool in IgA Nephropathy

IMPORTANCE

Although IgA nephropathy (IgAN) is the most common glomerulonephritis in the world, there is no validated tool to predict disease progression. This limits patient-specific risk stratification and treatment decisions, clinical trial recruitment, and biomarker validation.

OBJECTIVE

To derive and externally validate a prediction model for disease progression in IgAN that can be applied at the time of kidney biopsy in multiple ethnic groups worldwide.

DESIGN, SETTING, AND PARTICIPANTS

We derived and externally validated a prediction model using clinical and histologic risk factors that are readily available in clinical practice. Large, multi-ethnic cohorts of adults with biopsy-proven IgAN were included from Europe, North America, China, and Japan.

MAIN OUTCOMES AND MEASURES

Cox proportional hazards models were used to analyze the risk of a 50% decline in estimated glomerular filtration rate (eGFR) or end-stage kidney disease, and were evaluated using the R2D measure, Akaike information criterion (AIC), C statistic, continuous net reclassification improvement (NRI), integrated discrimination improvement (IDI), and calibration plots.

RESULTS

The study included 3927 patients; mean age, 35.4 (interquartile range, 28.0-45.4) years; and 2173 (55.3%) were men. The following prediction models were created in a derivation cohort of 2781 patients: a clinical model that included eGFR, blood pressure, and proteinuria at biopsy; and 2 full models that also contained the MEST histologic score, age, medication use, and either racial/ethnic characteristics (white, Japanese, or Chinese) or no racial/ethnic characteristics, to allow application in other ethnic groups. Compared with the clinical model, the full models with and without race/ethnicity had better R2D (26.3% and 25.3%, respectively, vs 20.3%) and AIC (6338 and 6379, respectively, vs 6485), significant increases in C statistic from 0.78 to 0.82 and 0.81, respectively (ΔC, 0.04; 95% CI, 0.03-0.04 and ΔC, 0.03; 95% CI, 0.02-0.03, respectively), and significant improvement in reclassification as assessed by the NRI (0.18; 95% CI, 0.07-0.29 and 0.51; 95% CI, 0.39-0.62, respectively) and IDI (0.07; 95% CI, 0.06-0.08 and 0.06; 95% CI, 0.05-0.06, respectively). External validation was performed in a cohort of 1146 patients. For both full models, the C statistics (0.82; 95% CI, 0.81-0.83 with race/ethnicity; 0.81; 95% CI, 0.80-0.82 without race/ethnicity) and R2D (both 35.3%) were similar or better than in the validation cohort, with excellent calibration.

CONCLUSIONS AND RELEVANCE

In this study, the 2 full prediction models were shown to be accurate and validated methods for predicting disease progression and patient risk stratification in IgAN in multi-ethnic cohorts, with additional applications to clinical trial design and biomarker research.

Prevalence-Based Targets Underestimate Home Dialysis Program Activity and Requirements for Growth

BACKGROUND

Many renal programs have targets to increase home dialysis prevalence. Data from a large Canadian home dialysis program were analyzed to determine if home dialysis prevalence accurately reflects program activity and whether prevalence-based assessments adequately reflect the work required for program growth.

METHODS

Data from home dialysis programs in British Columbia, Canada, were analyzed from 2005 to 2015. Prevalence data were compared to dialysis activity data including intakes and exits to describe program turnover. Using current attrition rates, recruitment rates needed to increase home dialysis prevalence proportions were identified.

RESULTS

We analyzed 7,746 patient-years of peritoneal dialysis (PD) and 1,362 patient-years of home hemodialysis (HHD). The proportion of patients on home dialysis increased by 3.34% over the ten years examined, while the number of prevalent home dialysis patients increased 2.65% per year and the number of patients receiving home dialysis at any time in the year increased 4.04% per year. For every 1 patient net home dialysis growth, 13.6 new patients were recruited. Patient turnover included higher rates of transplantation in home dialysis than facility-based HD. Overall, the proportion dialyzing at home increased from 29.3 to 32.6%.

CONCLUSIONS

There is high patient turnover in home dialysis such that program prevalence is an incomplete marker of total program activity. This turnover includes high rates of transplantation, which is a desirable interaction that affects home dialysis prevalence. The shortcomings of this commonly used metric are important for renal programs to consider, and better understanding of the activities that support home dialysis and the complex trajectories that home dialysis patients follow is needed.

External validation and clinical utility of a prediction model for 6-month mortality in patients undergoing hemodialysis for end-stage kidney disease

BACKGROUND

End-stage kidney disease is associated with poor prognosis. Health care professionals must be prepared to address end-of-life issues and identify those at high risk for dying. A 6-month mortality prediction model for patients on dialysis derived in the United States is used but has not been externally validated.

AIM

We aimed to assess the external validity and clinical utility in an independent cohort in Canada.

DESIGN

We examined the performance of the published 6-month mortality prediction model, using discrimination, calibration, and decision curve analyses.

SETTING/PARTICIPANTS

Data were derived from a cohort of 374 prevalent dialysis patients in two regions of British Columbia, Canada, which included serum albumin, age, peripheral vascular disease, dementia, and answers to the "the surprise question" ("Would I be surprised if this patient died within the next year?").

RESULTS

The observed mortality in the validation cohort was 11.5% at 6 months. The prediction model had reasonable discrimination (c-stat = 0.70) but poor calibration (calibration-in-the-large = -0.53 (95% confidence interval: -0.88, -0.18); calibration slope = 0.57 (95% confidence interval: 0.31, 0.83)) in our data. Decision curve analysis showed the model only has added value in guiding clinical decision in a small range of threshold probabilities: 8%-20%.

CONCLUSION

Despite reasonable discrimination, the prediction model has poor calibration in this external study cohort; thus, it may have limited clinical utility in settings outside of where it was derived. Decision curve analysis clarifies limitations in clinical utility not apparent by receiver operating characteristic curve analysis. This study highlights the importance of external validation of prediction models prior to routine use in clinical practice.

Evaluation of A 12-Month Pilot of Long-Term and Temporary Assisted Peritoneal Dialysis

Background

Peritoneal dialysis (PD) is challenging for patients with functional limitations, and assisted PD can support these patients, but previous reports of assisted PD have not examined the role of temporary assisted PD and had difficulty identifying adequate comparator cohorts.

Methods

Peritoneal Dialysis Assist (PDA), a 12-month pilot of long-term and temporary assisted PD was completed in multiple PD centers in British Columbia, Canada. Continuous cycler PD (CCPD) patients were identified for PDA by standardized criteria, and service could be long-term or temporary/respite. The PDA program provided daily assistance with cycler dismantle and setup, but patients remained responsible for cycler connections and treatment decisions. Outcomes were compared against both the general CCPD population and patients who met PDA criteria but were not enrolled (PDA-eligible).

Results

Fifty-three PDA patients had an 88% 1-year death- and transplant-censored technique survival that was similar to the general CCPD cohort (84%) and PDA-eligible cohort (86%). The PDA cohort had lower peritonitis rates (0.18 episodes/patient-year vs 0.22 and 0.36, respectively), but higher hospitalization (55% vs 34% and 35%, respectively). Long-term PDA cost approximately CDN$15,000/year in addition to existing dialysis costs. A total of 8/11 respite PDA patients (73%) returned to self-care PD after a median PDA use of 29 days, which costs $1,250/patient.

Conclusions

Peritoneal Dialysis Assist provides effective support to functionally-limited CCPD patients and yields acceptable clinical outcomes. The program costs less than transfer to HD or long-term care, which represents cost minimization for failing self-care PD patients. Respite PDA provides effective temporary support; most patients returned to self-care PD and service was cost-effective compared with alternatives of hospitalization or transfer to HD.

The Variability of Estimated Glomerular Filtration Rate Decline in Alport Syndrome

Background:

A progressive trajectory toward renal failure is common in patients with Alport syndrome. Genotype-phenotype correlations have been well described; however, the natural history of the trajectory toward renal failure is not well described.

Objective:

The objective of this study is to describe the natural history of renal function decline in a cohort of Alport syndrome patients.

Design:

Retrospective observational cohort study.

Setting:

British Columbia, Canada, chronic renal disease registry 1995-2012.

Patients:

37 biopsy proven Alport syndrome or hematuria with family history of Alport syndrome.

Measurements:

Serial estimated glomerular filtration rate (eGFR) Trajectory of renal decline described graphically by fitting a cubic smoothing spline to patient’s eGFR measures. Various time points within a trajectory were indexed, randomly sampled, and followed for 2 years to estimate portion of progressors (>5 mL/min/1.73 m2 /y decline), stable state (0-2 mL/min/1.73 m2 /y decline), and regressors (>2 mL/min/1.73 m2 /y incline).

Methods:

In this retrospective observational cohort study, participants were identified through a chronic renal disease registry in British Columbia, Canada, from 1995 to 2012. Inclusion criteria were biopsy proven or hematuria with a family history of Alport syndrome. Individual patients and family group members were studied. Trajectory of renal decline described graphically by fitting a cubic smoothing spline to patient’s serial estimated glomerular filtration rate (eGFR) measures. Various time points within a trajectory were indexed, randomly sampled, and followed for 2 years to estimate portion of progressors (>5 mL/min/1.73 m²/y decline), stable state (0-2 mL/min/1.73 m²/y decline), and regressors (>2 mL/min/1.73 m²/y incline).

Limitations:

Histological or genetic evidence of Alport syndrome is not available in all patients.

Results:

Median follow-up time was 48.2 months of 37 patients (78% male), with a median age of 36 (interquartile range [IQR], 18-47) and a median age of renal replacement therapy commencement (n = 23) of 38 (IQR = 20-52). Renal function changes were found to be heterogeneous overall, intra-individual and within families. Portion of progressors in eGFR 45-60 mL/min/1.73 m² was 73.7% (SD, 10.3), whereas 23.6% (SD, 11.0) remained stable. Within eGFR 30-45 mL/min/1.73 m², 45.6% (SD, 7.0) were progressors, whereas 53.4% (SD, 7.4) remained stable. A large portion of eGFR 15-30 mL/min/1.73 m² patients were stable (54.8%; SD, 8.4), whereas 25.7% (SD, 7.1) progressed and 19.5% (SD, 5.6) regressed.

Conclusions:

The renal decline in Alport syndrome patients is heterogeneous which has implications for designing clinical trials of interventions.

Time to revisit the problem of CIN? The low incidence of acute kidney injury with and without contrast in hospitalized patients: an observational cohort study

Background

Acute kidney injury (AKI) following imaging procedures with contrast medium in hospitalized patients is commonly attributed to contrast-induced nephropathy (CIN). This study sought to establish a benchmark of the incidence of AKI in hospitalized patients who underwent computed tomography (CT) scans, with and without intravenous contrast administration.

Methods

This was a multi-center observational cohort study. Hospitalized patients in four hospitals with CT scans during two time periods in 2012 and 2013 were included. AKI post-scan was defined as a change in serum creatinine (sCr) in absolute terms of ≥26.5 μmol/L (≥0.3 mg/dl), occurring within 7 days of the CT scan. AKI incidence was examined by study phases and CT-scan types using logistic regression models. Multinomial logistic regression was used to examine the proportions of sCr availability between two study phases.

Results

Three hundred and twenty-five patients in Period 1 and 518 patients in Period 2 were included in the study. The incidence of AKI in Period 1 was similar in those who received contrast and in those who did not (11.6 % [95 % C.I.: 6.5, 18.7] vs. 10.1 % [95 % C.I.: 5.1, 17.3]; p = 0.38). The incidence of AKI remained not significantly different between the two periods in those who received contrast (11.6 % [95 % C.I.: 6.5, 18.7] vs. 10.7 % [95 % C.I.: 6.8, 15.8]; p = 0.89) and those who did not (10.1 % [95 % C.I.: 5.1, 17.3] vs. 9.1 % [95 % C.I.: 5.2, 14.6]; p = 0.54). Among those who received contrast, there was a significant increase in the availability of both pre- and post- CT scan sCr in Period 2 compared to Period 1 (73.6 % [95 % C.I.: 67.7, 80.6] vs. 79.8 % [95 % C.I.: 75.2, 84.7]; p = 0.006).

Limitations

Our study was not targeted to specifically assess the impact of a prevention protocol on the incidence of AKI and was limited to settings within one health authority in the province.

Conclusion

In hospitalized patients, the incidence of AKI is low, not different between those who did and did not receive contrast, and was not impacted by improvement in the monitoring of sCr in at risk patients. A better understanding of the determinants of AKI post-contrast scan is required to improve strategies to reduce the incidence of AKI.

Fluid balance, change in serum creatinine and urine output as markers of acute kidney injury post cardiac surgery: an observational study

Background

Acute kidney injury (AKI) is defined as oliguria or rise in serum creatinine but oliguria alone as a diagnostic criterion may over-diagnose AKI.

Objectives

Given the association between fluid overload and AKI, we aimed to determine if positive fluid balance can complement the known parameters in assessing outcomes of AKI.

Design

Prospective observational study.

Setting

Teaching hospital in Vancouver, Canada.

Patients

111 consecutive patients undergoing elective cardiac surgery from January to April 2012.

Measurements

Outcomes of cardiac surgery intensive care unit (CSICU) and hospital length of stay (LOS) in relation to fluid balance, urine output and serum creatinine.

Methods

All fluid input and output was recorded for 72 hours post-operatively. Positive fluid balance was defined as >6.5 cc/kg. Daily serum creatinine and hourly urine output were recorded and patients were defined as having AKI according to the AKIN criteria.

Results

Of the patients who were oliguric, those with fluid overload trended towards longer LOS than those without fluid overload [CSICU LOS: 62 and 39 hours (unadjusted p-value 0.02, adjusted p-value 0.58); hospital LOS: 13 and 9 days (unadjusted p-value: 0.05, adjusted p-value: 0.16)]. Patients with oliguria who were fluid overloaded had similar LOS to patients with overt AKI (change in serum creatinine ≥ 26.5 µmol/L), [CSICU LOS: 62 and 69 hours (adjusted p value: 0.32) and hospital LOS: 13 and 14 days (adjusted p value: 0.19)]. Patients with oliguria regardless of fluid balance had longer CSICU LOS (adjusted p value: 0.001) and patients who were fluid overloaded in the absence of AKI had longer hospital LOS (adjusted p value: 0.02).

Limitations

Single centre, small sample, LOS as outcome.

Conclusions

Oliguria and positive fluid balance is associated with a trend towards longer LOS as compared to oliguria alone. Fluid balance may therefore be a useful marker of AKI, in addition to urine output and serum creatinine.

Pharmaceutical cost distribution in childhood chronic kidney disease

BACKGROUND

Chronic kidney disease (CKD) is associated with significant economic burdens to both patients and the healthcare system, but pharmaceutical cost analyses are uncommon despite drug therapy being a cornerstone of CKD management.

METHODS

This observational, retrospective review of drug cost distribution at a single tertiary care pediatric nephrology program in Canada was conducted on prevalent patients with CKD aged 1 month to 20 years, between 1 January and 31 December 2009.

RESULTS

The time-adjusted annual pharmaceutical cost of our cohort (n = 148) was just below US $250,000 with a cost per patient per year of $1,800. The highest costs were in the growth and nutrition category, followed by anemia, hypertension and bone metabolism. Total drug cost per patient increased as CKD stage advanced. Adherence was not demonstrated in any drug category, and the mean daily pill burden was nine (range 2-23).

CONCLUSIONS

This study has shown that while the annual pharmaceutical costs on a per patient basis are similar between children and adults, the cost distribution is very different. An increase in awareness of the unique needs of the pediatric population should allow for more cost-effective financial planning in pediatric CKD clinics.

Urinary NGAL levels before and after coronary angiography: a complex story

BACKGROUND

We describe urinary neutrophil gelatinase-associated lipocalin (uNGAL) values in association with clinical characteristics and urinary parameters in adults undergoing coronary angiography.

METHODS

This is an observational study of consecutive patients who underwent elective coronary angiography during a 4-month period in a large urban tertiary care hospital.

RESULTS

One hundred and thirteen patients were enrolled, and 100 had sufficient data to be included in the analyses. A large range of preprocedural uNGAL levels were observed (range 1-269 ng/mg Cr). Median preprocedural uNGAL was 8 ng/mg Cr. Age (P = 0.009), serum creatinine (P = 0.077) and albumin excretion (P = 0.009) were significant predictors of baseline uNGAL. Half the cohort demonstrated an increase and half a decrease in the absolute values of uNGAL after angiography, irrespective of preprocedural levels.

CONCLUSIONS

We observed variable, but relatively low absolute levels of uNGAL prior to angiography in this 'cardiac' cohort. Only age, serum creatinine and albumin excretion could explain some of this variability. When designing studies of at-risk individuals where uNGAL may be used as a marker for acute kidney injury, this variability should be taken into account.

Differences in progression of CKD and mortality amongst Caucasian, Oriental Asian and South Asian CKD patients

BACKGROUND

Ethnic differences in chronic kidney disease (CKD) progression are not well characterized but are of interest across and within countries.

METHODS

We followed up a large CKD cohort of patients of three different ethnic origins [Caucasian, Oriental Asian (OA) and South Asian (SA)] from time of nephrology referral in a universal health care system. Key outcomes were time to death and/or renal replacement therapy (RRT) and rate of decline in estimated GFR (eGFR). The effects of known predictors (blood pressure, proteinuria, age, sex, diabetes, cardiovascular disease and medications) and of other laboratory abnormalities were assessed using multivariate modelling techniques, including both Cox proportional hazards and competing risk approach.

RESULTS

The cohort comprised 3444 patients (2626 Caucasians, 397 OA and 421 SA). All-cause mortality rates are higher in Caucasians than SA or OA [hazard ratio (HR) 0.693 and 0.803, P < 0.05]. OA and SA have higher risks of progressing to RRT (HR 1.281 and 1.349, P < 0.05) and lower risks of death before RRT (HR 0.718 and 0.520, P < 0.05) compared to Caucasians after adjustment for usual risk factors. However, when adjusted for additional laboratory abnormalities, differences did not persist for progression, but did for survival advantage of Asians. The median rate of decline in eGFR (in millilitres per minute per 1.73 m(2)) was significantly slower in Caucasians (-2.11) than in OA (-2.93) or SA (-3.56), P = 0.027.

CONCLUSIONS

Asians appear to have faster CKD progression and lower mortality rates compared to Caucasians. This effect is not explained by the usual variables, but rates of progression may be related to differences in severity of laboratory abnormalities at different CKD stages. Further research is needed to understand the implications of these findings.

Elevated osteoprotegerin is associated with all-cause mortality in CKD stage 4 and 5 patients in addition to vascular calcification

BACKGROUND

Cardiovascular disease is the leading cause of death in the chronic kidney disease (CKD) population. The mechanisms of vascular damage are not fully understood. The objective of this study was to prospectively investigate the importance of novel mediators of vascular damage, in conjunction with vascular calcification (VC), on survival.

METHODS

A total of 134 subjects [60 haemodialysis (HD), 28 peritoneal dialysis (PD) and 46 CKD stage 4] were studied. All survivors completed 40 months of follow-up. VC was measured using multi-slice spiral CT of the superficial femoral artery. Circulating osteoprotegerin (OPG), Fetuin-A and high sensitivity C-reactive protein (hs-CRP) were measured in addition to standard clinical biochemical analysis.

RESULTS

After a 40-month follow-up, 31 patients had died (27 men and 4 women). Of 31 subjects, 31 had evidence of significant VC. The majority of deaths were in the HD group (48%), 36% were PD subjects and 16% were CKD subjects. The outcome of interest was survival at the end of follow-up. Multivariate logistical regression analysis revealed male gender [OR 8.06 (1.34-48.450) P = 0.02], OPG >25 pmol/L [OR 5.31(1.35-20.88) P = 0.02] and hypoalbuminaemia [OR 0.26 (0.12-0.56) P < 0.01], were associated with increased odds of death.

CONCLUSION

We have previously reported that VC and low albumin predict death in CKD stages 4 and 5 over a 2-year follow-up period. These data show that OPG, independent of CRP, is also associated with a negative outcome. The mechanisms remain to be elucidated; however, it is likely that they are associated with vascular damage through mechanisms in addition to VC.

A comparison of the predictive performance of different methods of kidney function estimation in a well-characterized HIV-infected population

BACKGROUND

Glomerular filtration rate (GFR) estimation equations have never been validated in the HIV population. This pilot study aimed to compare all currently available methods of kidney function assessment with nuclear GFR in HIV-infected adults.

METHODS

Patients underwent GFR measurement with (99m)Tc-diethylenetriaminepentaacetic acid (Tc-99m Pentetate), and measured values were compared with results of creatinine-based estimation equations [abbreviated 4-variable Modification of Diet in Renal Disease (MDRD) formula and Cockcroft-Gault (CG) formulae], 24-hour urine creatinine clearance and estimated cystatin C GFR.

RESULTS

Twenty-seven HIV-infected adults were studied. Most were male and Caucasian, with a mean age of 52 years. Median CD4 was 290 cells/mm(3), 70% of patients had HIV RNA <50 copies/ml and all were receiving highly active antiretroviral therapy (median 5 drugs). Median Tc-99m Pentetate-GFR was 91 ml/min/1.73 m(2). Despite greater bias and similar accuracy, the MDRD formula was more precise than the CG formula, regardless of whether CG estimations were corrected for ideal body weight or body surface area. Relative accuracy within 30% of nuclear GFR was greater for the MDRD formula than for all other methods. The performance of 24-hour urine creatinine clearance was similar to that of the MDRD formula for patients with GFR <90 ml/min/1.73 m(2), although it performed less well at higher GFR. The performance of cystatin C GFR was inferior to that of all the creatinine-based methods.

CONCLUSIONS

While no method of kidney function estimation performed highly, both 24-hour urine creatinine clearance and the MDRD formula performed with a level of precision and accuracy sufficient for clinical decision making. Our findings support the preferential use of the MDRD formula in the treated HIV population and suggest that there are no HIV-specific factors that limit equation applicability. Larger validation studies are needed to confirm our findings and allow generalization to the HIV population at large.

Exploration of association of 1,25-OH2D3 with augmentation index, a composite measure of arterial stiffness

BACKGROUND AND OBJECTIVES

Abnormalities in mineral metabolism [calcium, phosphate, and immunoreactive parathyroid hormone (PTH)] and vitamin D have been linked to increases in central arterial stiffness. Central arterial stiffness can be measured using noninvasive technologies, including augmentation index (AIx), a composite measure of arterial stiffness.

DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS

In 131 outpatients identified from individual cardiac or kidney disease clinics, we examined conventional demographic and laboratory risk factors, vitamin D levels (1,25-OH2D3 and 25-OHD3), and markers of inflammation or endothelial function [C-reactive peptide (hsCRP), matrix metalloproteinase 2 (MMP-2), matrix metalloproteinase 9 (MMP-9), and IL-6] in relationship to AIx.

RESULTS

The median eGFR was significantly different between clinics (range 25-81 ml/min). Subjects with higher phosphate or MMP-9 levels were found to have a higher AIx (P = 0.02 and 0.07, respectively). Lower 1,25-OH2D3 levels or reduced eGFR were associated with higher AIx (P = 0.002 and 0.005, respectively). The associations between 1,25-OH2D3 and phosphate levels and AIx were observed for values within the normal range. No association was noted for calcium, iPTH, 25-OHD3, or hsCRP and AIx. Adjusting for potential confounders [eGFR, calcium, phosphate, and (log) iPTH] the association of lower 1,25-OH2D3 with AIx remained statistically significant.

CONCLUSION

This exploratory study demonstrates a significant association between AIx and 1,25-OH2D3 in a diverse group with cardiac, kidney disease, or both. These increasing understanding of the role of vitamin D in vascular health lends a context to these findings and raises questions as to additional modifiable risk factors in complex patients. Further studies are required.

Variability and risk factors for kidney disease progression and death following attainment of stage 4 CKD in a referred cohort

BACKGROUND

The outcomes of patients referred to nephrologists are not well described in large cohorts. The objectives of this analysis are to describe the predictors of rapid progression of kidney disease and death in patients followed up by nephrologists.

STUDY DESIGN

Retrospective study.

SETTING & PARTICIPANTS

A cohort derived from all patients registered in the provincial database was formed that included all patients with index estimated glomerular filtration rate (eGFR) less than 30 mL/min/1.73 m(2), at least 3 subsequent eGFR values, and 4 months of follow-up between January 2000 and January 2004.

PREDICTORS

Variables used to predict outcomes included baseline eGFR, duration of follow-up before eGFR less than 30 mL/min/1.73 m(2), age, sex, ethnicity, presence of diabetes, blood pressure, level of proteinuria, hemoglobin level, phosphate level, calcium level, parathyroid hormone level, and use of angiotensin-converting enzyme inhibitors or angiotensin receptor blockers, erythropoiesis-stimulating agents, and vitamin D.

OUTCOMES

Key outcomes of interest were death, dialysis therapy start, or loss of GFR greater than 5 mL/min/1.73 m(2)/y.

RESULTS

4,231 patients met inclusion criteria. Mean age was 67 years. Median follow-up was 31 months. During the first 2 years of follow-up, 24% started dialysis therapy, 1% received a transplant, 7% died, and 1% was lost to follow-up. Statistically significant variables associated with more rapid kidney disease progression differ from those that predict death. Younger age, male sex, higher eGFR, higher systolic and diastolic blood pressure, lower hemoglobin level, higher phosphorus and parathyroid hormone levels, and greater proteinuria are associated with more rapid kidney disease progression, and use of angiotensin-converting enzymes/angiotensin receptor blockers are protective. Older age, lower diastolic blood pressure, lower hemoglobin level, and higher phosphorous and parathyroid hormone levels are associated with death, whereas vitamin D use is protective.

LIMITATIONS

Results cannot be generalized to unreferred patients with eGFR less than 30 mL/min/1.73 m(2).

CONCLUSION

The clinical course of patients with chronic kidney disease stage 4 is variable. Targeted therapy aimed at modifiable risk factors needs to be evaluated to determine benefits of this approach.

Variability of hepatitis B testing in British Columbian ESRD patients: the case to focus on implementation of guidelines

BACKGROUND

Hepatitis B virus (HBV) immunization protocols are routinely followed in dialysis units. Recommendations for retesting and booster dose administration are variable and less well known.

DESIGN

Quality improvement report.

SETTING & PARTICIPANTS

Provincial dialysis cohort in all 5 regional centers in British Columbia (n = 1,055).

QUALITY IMPROVEMENT PLAN

(1) Describe the variations in HBV testing practice patterns between centers and modalities of dialysis, (2) propose an evidence-based protocol for HBV follow-up testing, and (3) compare the current practice for HBV follow-up testing with the protocol.

MEASURES

(1) Number of HBV tests performed based on geographic center and dialysis modality; (2) tabulation of local, national, and international guidelines to determine concordance and develop British Columbian protocol, and (3) percentage of patients who received recommended HBV testing based on protocol.

RESULTS

(1) Significant variation noted in HBV testing frequency among the 5 regional centers and between hemodialysis and peritoneal dialysis patients (P < 0.001); (2) current available guidelines generally are concordant, but vary in regard to frequency of follow-up testing; and (3) comparing recommended testing frequency with actual testing, 50% of patients were tested as recommended; 13%, less than recommended; and 37%, more than recommended. Hemodialysis patients often were tested more than recommended (hemodialysis, 47% versus peritoneal dialysis, 16%; P < 0.01). Patients with current or past HBV infection were tested more than recommended (P < 0.01). All variability remained significant when adjusted for age, sex, and dialysis therapy duration in a multivariate model.

LIMITATIONS

The cohort was ascertained from laboratory data; therefore, information for vaccination and booster dose administration was not available.

CONCLUSION

In a cohort of dialysis patients initially screened for hepatitis B, 50% of patients are being appropriately monitored with retesting compared with an evidence-based protocol. Patients with known HBV infection and hemodialysis patients are being tested more than recommended. Adherence to a protocol for retesting would ensure appropriate follow-up and reduce unnecessary retesting, potentially leading to significant cost savings.

Coronary artery calcification scores in patients with chronic kidney disease prior to dialysis: reliability as a trial outcome measure

BACKGROUND

Coronary artery calcification (CAC) is prevalent in patients with chronic kidney disease (CKD). Data on the reliability and validity of high-resolution computerized tomography (HRCT) in patients with CKD is lacking. The purpose of this study was to evaluate the inter- and intra-reviewer agreement and inter-scan reproducibility of CACS measurement with HRCT in a cohort of patients with CKD prior to dialysis, and to compare the change in CACS at 30 minutes to the change in CACS over 1 year.

METHODS

Thirty-three patients with CKD not yet on dialysis underwent an HRCT scan at baseline and 1 year to assess for CAC and CAC progression. Two radiologists independently reviewed films and each radiologist re-reviewed a randomly selected subset of films they had previously viewed, to assess for inter-reviewer and intra-reviewer reliability, respectively. Patients underwent a repeat scan within 30 min of the first baseline scan to assess for inter-scan reproducibility.

RESULTS

At baseline, eight patients (24%) had no CAC. Of the 25 patients (76%) with CAC, 10 (40%) had severe calcification. Intra-reviewer agreement was 83%. Inter-reviewer agreement ranged between 77 and 94%. Six (27%) of the patients with >30 baseline CACS had >15% change in CACS following repositioning. Four of these patients had an increase in CACS with position change [18% (95% CI: 5-40%)]. Of the 21 patients who underwent a follow-up scan at 1 year, 7 (33%) demonstrated CACS progression.

CONCLUSIONS

There is significant imprecision in HRCT-derived CACS in CKD patients. This suggests a need for standardization of methods of CACS measurement with HRCT.

Outcomes of a provincial home haemodialysis programme--a two-year experience: establishing benchmarks for programme evaluation

INTRODUCTION

The province of British Columbia has the only coordinated provincial programme for home-based haemodialysis (HHD) in Canada. The centrally coordinated and locally administered programme was initiated in 2002 as a pilot project, and was firmly established with secured funding in 2004. HHD programmes have reported successful outcomes with respect to patients' well-being, haemodynamic stability and improvement of clinical and biochemical parameters in small selected groups of patients.

METHODS

This report describes the 2-year outcomes of a provincial programme, in which more liberal criteria for patient selection have been applied, and multiple sites have trained and managed the patients over a large geographic area. As a 'newer' modality, it is important to review outcomes objectively so as to determine the true value of this home-based programme as an alternative to other home-based therapies such as peritoneal dialysis.

RESULTS

One hundred and five patients who completed training and commenced home therapy between April 2004 and March 2006 were followed, for a total of 163.23 patient-years (PY). The average age was 52; 71% were male and the majority (58%) were Caucasian. Mean biochemical and clinical parameters were all within provincial and national target ranges at baseline and at the time of study follow-up cessation. Overall, 34 individual patients required hospital admission and 95% of the cohort required at least one in-centre run after training was completed (0.5 hospital admissions and 11 in-centre run per PY of HHD delivered). One- and 2-year technique survivals were 81% and 61% respectively, which were 85% and 74% when censored for transplantation. We were unable to demonstrate any significant predictors of technique survival using demographic, biochemical or other variables.

CONCLUSION

This is the first report of HHD programme technique survival in a large provincial cohort. The 2-year technique survival of this cohort is comparable to reports of technique survival in peritoneal dialysis. These data can be used to benchmark programmes, and to foster further research to determine factors that may improve HHD technique survival.