Incidence and outcomes of kidney replacement therapy for end-stage kidney disease due to primary glomerular disease in Europe: findings from the ERA Registry

BACKGROUND AND HYPOTHESIS

Primary glomerular disease (PGD) is a major cause of end-stage kidney disease (ESKD) leading to kidney replacement therapy (KRT). We aimed to describe incidence (trends) in individuals starting KRT for ESKD due to PGD and to examine their survival and causes of death.

METHODS

We used data from the European Renal Association (ERA) Registry on 69 854 patients who started KRT for ESKD due to PGD between 2000 and 2019. ERA primary renal disease codes were used to define six PGD subgroups. We examined age and sex standardized incidence, trend of the incidence, and survival.

RESULTS

The standardized incidence of KRT for ESKD due to PGD was 16.6 per million population (pmp), ranging from 8.6 pmp in Serbia to 20.0 pmp in France. IgA nephropathy (IgAN) and focal segmental glomerulosclerosis (FSGS) had the highest incidence of 4.6 pmp and 2.6 pmp, respectively. Histologically non-examined PGDs represented over 50% of cases in Serbia, Bosnia and Herzegovina, and Romania and were also common in Greece, Estonia, Belgium, and Sweden. The incidence declined from 18.6 pmp in 2000 to 14.5 pmp in 2013, after which it stabilized. All PGD subgroups had five-year survival probabilities above 50%, with crescentic glomerulonephritis having the highest risk of death (adjusted hazard ratio: 1.8 [95% confidence interval: 1.6-1.9]) compared with IgAN. Cardiovascular disease was the most common cause of death (33.9%).

CONCLUSION

The incidence of KRT for ESKD due to PGD showed large differences between countries and was highest and increasing for IgAN and FSGS. Lack of kidney biopsy facilities in some countries may have affected accurate assignment of the cause of ESKD. The recognition of the incidence and outcomes of KRT among different PGD subgroups may contribute to a more individualized patient care approach.

Effect of residual kidney function and dialysis adequacy on chronic pruritus in dialysis patients

BACKGROUND

Chronic Kidney Disease-associated pruritus (CKD-aP) is common in dialysis patients, associated with lower quality of life and increased risk of death. We investigated the association between residual eGFR, dialysis adequacy or serum phosphate level and CKD-aP in incident dialysis patients.

METHODS

1256 incident hemodialysis (HD) and 670 peritoneal dialysis (PD) patients (>18y) from the Netherlands Cooperative Study on the Adequacy of Dialysis study were included (1997-2007) and followed until death, transplantation, or max 10y. CKD-aP was measured using a single item of the KDQOL-36. The associations were studied by logistic and linear regression analyses, adjusted for potential baseline confounders.

RESULTS

At baseline mean (SD) age was 60 (16), 62% were men and median (IQR) residual eGFR was 3.4 (1.7-5.3) ml/min/1.73m2. The prevalence of CKD-aP (∼70%) was similar in HD and PD. It was observed that 12 months after starting dialysis (after multivariable adjustment) each 1 ml/min/1.73m2 higher residual eGFR, one unit higher total weekly Kt/V, or 1 mmol/L lower serum phosphate level was associated with lower burden of CKD-aP in HD and PD patients of -0.05 (95%CI:-0.09;-0.02) and -0.09 (95%CI:-0.13;-0.05), -0.15 (95%CI:-0.26;-0.05) and -0.35 (95%CI:-0.54;-0.16), and of -0.34 (95%CI:-0.17;-0.51) and -0.45 (95%CI:-0.19;-0.71), respectively. We found no association between dialysis Kt/V and CKD-aP.

CONCLUSIONS

Higher residual eGFR and lower serum phosphate level, but not the dialysis dose, were related with lower burden of CKD-aP in dialysis patients.

MO337: Higher Antibody Response After 2 Vaccinations With MRNA-1273 as Compared With BNT162B2 and AZD1222 in High-Risk Kidney Patients

BACKGROUND AND AIMS

Lower antibody responses after SARS-Cov-2 vaccination have been reported in patients with severely impaired kidney function or patients with kidney replacement treatment. We compared humoral responses and reported adverse events of three vaccines (mRNA-1273, BNT162b2 and AZD1222) in kidney transplant recipients (KTRs), dialysis patients, patients with CKD stages G4–G5 and control subjects without kidney disease.

METHOD

KTRs, dialysis patients and patients with CKD stages G4–G5 were vaccinated with either mRNA-1273, BNT162b2 or AZD1222 during the Dutch SARS-CoV-2 vaccination program. Control subjects were all vaccinated with mRNA-1273. Blood samples were obtained at 1 month after two vaccinations by home-based finger prick tests and were analysed for the presence of IgG antibodies against the receptor-binding domain of the spike protein of SARS-CoV-2 using the Sanquin anti-SARS-CoV-2 RBD IgG ELISA assay. Primary endpoints were the antibody titer and reported systemic adverse events (AEs) at 1 month after the second vaccination. Multivariate regression analysis was performed on the difference between vaccines with respect to antibody titer and AEs after correction for sex, ethnicity, BMI, eGFR, dialysis vintage, transplantation characteristics and use of immunosuppressive drugs.

RESULTS

A total of 2468 KTRs, 480 dialysis patients, 400 patients with CKD stages G4–G5 and 186 control subjects were enrolled. KTRs had lower antibody titers (66 [8–573] BAU/mL) in comparison to dialysis patients [1375 (431–2896) BAU/mL], patients with CKD stages G4–G5 [2097 (828–4077) BAU/mL] and control subjects [3713 (2291–6451) BAU/mL]. mRNA-1273 demonstrated a higher antibody titer compared with BNT162b2 in KTR [72 (9–638) versus 21 (6–128) BAU/mL; P < .001), dialysis patients [1675 (573–3031) versus 636 (216–1416) BAU/mL; P < .001] and patients with CKD stages G4–G5 [2879 (1425–5311) versus 1063 (389–1939) BAU/mL; P < .001). In a similar pattern, mRNA-1273 demonstrated a higher antibody titer compared with AZD1222 (P < .001 in all groups). Multivariate analysis revealed that BNT162b2 and AZD1222 were significantly associated with lower antibody levels compared with mRNA-1273 in all 3 patient groups. BNT162b2 demonstrated less frequently systemic AEs compared with mRNA-1273 in KTRs (12% versus 27%; P < .001), dialysis patients (12% versus 29%; P = .007) and in patients with CKD G4–G5 (18% versus 67%, P < .001). AZD1222 demonstrated less systemic AEs compared with mRNA-1273 only in patients with CKD stages G4–G5 (39% versus 67%; P = .03). Multivariate analysis revealed that BNT162b2 was associated with fewer systemic AEs in only dialysis patients (P = .04) and patients with CKD stages G4–G5 (P = .02).

CONCLUSION

mRNA-1273 demonstrated significantly higher antibody levels at 1 month after 2 vaccinations as compared with BNT162b2 and AZD1222 in high-risk patients with kidney disease. BNT162b2 was associated with a fewer systemic AEs in dialysis patients and patients with CKD stages G4–G5, although these AEs were mild and self-limiting. mRNA-1273 may therefore be considered as the preferred SARS-CoV-2 vaccine in high-risk patients with kidney disease. Whether the higher antibody response following vaccination with mRNA-1273 sustains and results in a better protection against COVID-19 is yet to be analysed.

MO184: Development and Validation of a Multivariable Prediction Model for Nonseroconversion after SARS-COV-2 Vaccination in Kidney Transplant Recipients

BACKGROUND AND AIMS

Kidney transplant recipients (KTRs) are still at risk of fatal COVID-19 disease after SARS-CoV-2 vaccination, even after a third booster vaccination. With the spread of new SARS-CoV-2 variants, great urgency exists for a better understanding of the factors that impact the immune response in these patients. Our aim was to predict nonseroconversion after SARS-CoV-2 vaccination to understand the factors that may disrupt the humoral response in KTRs.

METHOD

A multivariable logistic regression model was developed and validated that uses routinely available clinical and laboratory information to predict nonseroconversion after two doses of SARS-CoV-2 mRNA vaccination in KTRs. KTRs were prospectively enrolled to the Dutch REnal patients COVID-19 VACcination (RECOVAC) consortium, specifically to the Immune Response (IR) study with four participating university medical centres in the Netherlands. The discovery cohort consisted of three participating centres (Amsterdam UMC, Radboud UMC Nijmegen and Erasmus MC Rotterdam), and the validation cohort of patients treated in UMC Groningen. A large second validation set from the RECOVAC consortium (LESS-CoV-2) was used to test a more simplified version of the model without lymphocyte counts. All participants received two doses of the mRNA-1273 COVID-19 vaccine (Moderna) and had no history of SARS-CoV-2 infection. Participants were classified as responder or non-responder based on seroconversion at day 28 following the second vaccination with a threshold for seropositivity based on receiver operator curve analysis set at S1-specific IgG antibody concentration ≥10 BAU/mL.

RESULTS

The discovery cohort included 215 KTRs of which 126 responders and 89 non-responders. After backward selection, 6 out of 19 factors remained predictive for nonseroconversion: increased age, lower lymphocyte count, lower estimated glomerular filtration rate (eGFR), shorter time after transplantation, not using steroids and the use of mycophenolate mofetil/mycophenolic acid (MMF/MPA) (Figure 1). The area under the curve (AUC) of the receiver operating characteristics was 0.83 (95% confidence interval 0.78–0.89) in the discovery cohort after adjustment for optimism and 0.84 (0.74–0.94) in external validation of the UMC Groningen cohort (n = 73), and 0.75 (0.72–0.77) in external validation of the LESS-CoV-2 dataset (n = 2484). In addition, MMF/MPA appeared to have a dose-dependent unfavourable association with the S1 IgG antibody titer (Figure 2).

CONCLUSION

Six predictors allow for a better understanding of the process of the development of the humoral response in KTRs. These predictors could be applied to individualized patient counseling and treatment strategy during the COVID-19 pandemic and future innovative vaccine trial design for this complex patient group.

MO899: The Clinical frailty Scale is Useful for ICU Triage in Dialysis Patients With COVID-19–An Eracoda Analysis

BACKGROUND AND AIMS

during the COVID-19 pandemic, several guidelines have recommended the use of the Clinical Frailty Scale (CFS) for triage of critically ill patients with COVID-19 in case of shortage in ICU resources. However, no data on using CFS assessment for ICU triage for dialysis patients is yet available. This study evaluates whether CFS is associated with mortality rates in a cohort of hospitalized dialysis patients with COVID-19.

METHOD

the analyses are based on data of the European Renal Association COVID-19 Database (ERACODA). Dialysis patients who presented with COVID-19 between 1 February 2020 and 30 April 2021 and with complete information on CFS and vital status at 3 months were included. Study outcomes were hospital and ICU admission rates and hospital and ICU mortality at 3 months after hospital admission. Cox regression analyses were performed to assess the association of CFS category (≤5 versus ≥ 6) and study outcomes in line with Dutch ICU triage guidelines for COVID-19. Furthermore, additional subgroup analyses were performed to assess the association between CFS and 3-month mortality by age category (<65, 65–75 and >75 years).

RESULTS

among a total of 2206 dialysis patients (mean age = 67.2 (14.1) years, male sex = 61%), 1694 (77%) had CFS ≤ 5 and 514 (23%) had CFS ≥ 6. Hospitalization rate was comparable in patients with CFS ≤ 5 and in patients with CFS ≥ 6 (67 and 71%, respectively), whereas the rate of ICU admission was higher in patients with CFS ≤ 5 than in patients with CFS ≥ 6 (16 versus 9%, p = 0.001). Among 1501 hospitalized patients, 3-month mortality was 26% of patients with CFS ≤ 5 and 59% in patients with CFS ≥ 6 (P < 0.001). Multivariate analysis with adjustment for patient demographics, smoking status and BMI revealed that CFS ≥ 6 was associated with hospital mortality [aHR 2.27 (1.88–2.74) versus CFS ≤ 5; P < 0.001) with a significant interaction for age (P = 0.029). aHR was 4.00 (2.56–6.37; CFS ≥ 6 versus CFS ≤ 5; P < 0.001) in patients < 65 years, aHR was 1.87 (1.33–2.64; CFS ≥ 6 versus CFS ≤ 5; P < 0.001) in patients 65–75 years and aHR was 2.12 (1.64–2.75; CFS ≥ 6 versus CFS ≤ 5; P < 0.001) in patients >75 years. Among 219 ICU admitted patients, 3-month mortality was 60% of the patients with CFS ≤ 5 and 91% in the patients with CFS ≥ 6, respectively. Multivariate analysis with adjustment for patient demographics, smoking status and BMI revealed that CFS ≥ 6 was associated with ICU mortality [aHR 1.80 (1.17–2.77); CFS ≥ 6 versus CFS ≤ 5; P = 0.002].

CONCLUSION

more frail dialysis patients with CFS ≥ 6 who are hospitalized for COVID-19 were less often admitted to the ICU, but in case they were admitted to the ICU they have a very high mortality of 91% in this cohort study. In fit to mildly frail dialysis, patients who were admitted to the ICU, mortality rates are lower. The association between frailty and hospital mortality is interacted by age with the strongest association in patients younger than 65 years. These findings suggest that CFS may be a useful complementary triage tool for ICU admission of dialysis patients during the ongoing COVID-19 pandemic.

FC 027COVID-19 IN PATIENTS ON KIDNEY REPLACEMENT THERAPY - CLINICAL CHARACTERISTICS AT TRIAGE ASSOCIATED WITH ADMISSION, READMISSION AND SHORT-TERM OUTCOMES

Background and Aims

Patients on kidney replacement therapy (KRT) are at high risk of developing severe COVID-19 illness and often require high intensity care and utilisation of hospital resources. During the ongoing pandemic, the optimal care pathway and triage for KRT patients presenting with varying severity of COVID-19 illness is unknown. We studied clinical factors and outcomes associated with admission, readmission and short-term outcomes.

Method

Data from the European Renal Association COVID-19 Database (ERACODA) was analysed. This database includes granular data on dialysis patients and kidney transplant recipients with COVID-19 from all over Europe. The clinical and laboratory features at first presentation of hospitalized and non-hospitalized patients and those who returned for second presentation were studied. In addition, possible predictors of outcome in those who were not hospitalized at first presentation were identified.

Results

Among 1,423 KRT patients (haemodialysis; 1017/kidney transplant; 406) with COVID-19, 25% (n=355) were not hospitalized at first presentation. Of them, only 10% (n=36), presented for a second time in the hospital. The median interval between the first and second presentation was 5 days (Interquartile interval: 2-7 days). Patients who re-presented had worsening of pulmonary symptoms, a fall in oxygen saturation (97% to 90%), and an increase in C-reactive protein (26 mg/L to 73 mg/L) between their attendances. Patients who re-presented after initial assessment were older (72 vs. 63 years) and initially more often had pulmonary symptoms and abnormalities on lung imaging compared with those who did not present for a second time. The 28-day mortality rate of patients admitted at the second presentation was similar to that of patients admitted at first presentation (26.5% vs. 29.7%, p=0. 61). Among patients who were not hospitalized at first presentation (mortality 6%), age, prior smoking, clinical frailty scale, and shortness of breath at first presentation were identified as predictors of mortality.

Conclusion

KRT patients with COVID-19 and mild pulmonary abnormalities and no signs of pulmonary insufficiency can be safely returned without hospitalization. These patients should be advised to seek immediate contact when they develop respiratory distress. Our findings provide support for a risk-stratified clinical approach to admissions of KRT patients presenting with COVID-19. The study findings may be valuable for clinical triage and optimising hospital capacity utilisation during the ongoing pandemic.

MO935HEALTH RELATED QUALITY OF LIFE AFTER KIDNEY TRANSPLANTATION: A SYSTEMATIC REVIEW

Background and Aims

Health-related quality of life (HRQOL) is becoming an increasingly important outcome in kidney transplantation besides graft function and patient survival. It is of clinical interest to understand whether kidney transplant recipients (KTRs) experience better HRQOL after the invasive procedure and to what extent they can restore HRQOL. To the best of our knowledge, the last relevant systematic review and meta-analysis, which compared HRQOL in KTRs to patients on dialysis, only included eligible publications before 2005. With the considerable improvement in nephrology care and the exponential increase in studies focusing on HRQOL in the past two decades, an updated overview of the current literature is needed. Moreover, to gain a comprehensive picture of HRQOL in KTRs, it is also necessary to include relevant comparison groups such as the general population and healthy controls to understand to which extent HRQOL can be restored to a “pre-CKD” level. To describe HRQOL in KTRs, this systematic review summarizes the published literature to date that compared HRQOL of KTRs with other relevant populations (i.e. patients receiving dialysis, patients on the waiting list for kidney transplantation, patients with chronic kidney disease [CKD] not receiving dialysis, the general population, and healthy controls) and themselves before kidney transplantation. To avoid potential bias, we include studies using different HRQOL questionnaires.

Method

A thorough literature search was conducted in PubMed, EMBASE, Web of Science, and COCHRANE Library. Studies were included when published between January 2000 and October 2020, and when comparing HRQOL in adult KTRs to the relevant populations. The quality of included studies was assessed using the Risk Of Bias Assessment tool for Non-randomized Studies (RoBANS). Prespecified study characteristics and HRQOL scores were extracted. Due to substantial clinical and methodological heterogeneity, results were summarized in a narrative manner without pooled estimates.

Results

44 studies comprising 6929 KTRs were included in this systematic review. The mean age of KTRs in all studies ranged from 29 to 72 years old, and only two studies were conducted in an elderly cohort (≥ 65 years). The majority of studies (93%) reported a higher percentage of male KTRs (median 62%; range 43% to 86%). The average time of HRQOL-measurements after kidney transplantation ranged from 1 to 234 months after the operation. 50% of the studies had a cross-sectional design; 32% had a prospective, and 18% had a retrospective design; and 55% of the studies were single-center studies. While taken into account study heterogeneity, KTRs reported a higher HRQOL after kidney transplantation compared to pre-transplantation and compared to patients receiving dialysis with or without being on the waiting list, especially in disease-specific domains (i.e. burden of kidney disease, effect of kidney disease, and symptoms). Additionally, KTRs had comparable to marginally higher HRQOL compared to patients with CKD stage 3-5. When compared to healthy controls or the general population, KTRs reported similar HRQOL in the first one or two years after kidney transplantation, and lower physical HRQOL and lower to comparable mental HRQOL with an average post-transplant time longer than two years.

Conclusion

Patients generally report better HRQOL after successful kidney transplantation compared to themselves before the operation and patients receiving dialysis with or without waiting for kidney transplantation, but HRQOL of KTRs does not return to “pre-CKD” HRQOL levels. Future studies investigating risk factors for impaired HRQOL are needed to maximize the long-term benefit of kidney transplantation.

FC 117TIME TRENDS IN PROBABILITY OF STARTING HOME DIALYSIS OVER A 20 YEAR PERIOD: A DUTCH REGISTRY STUDY

Background and Aims

A growing number of patients suffers from End Stage Kidney Disease(ESKD), causing a logistical and economic burden to the healthcare system. Utilization of home dialysis is low in many countries worldwide, although home dialysis has several advantages including higher quality of life and possibly lower costs. The aim of this study is to explore time trends in the use of home dialysis in the Netherlands.

Method

Anonymized registry data from the Dutch Renal Registry (RENINE) were used for this study. All dialysis episodes of adult patients who started dialysis treatment between 1997 through 2016 in the Netherlands were included, including those who previously underwent kidney transplantation. Dialysis episodes shorter than 90 days were excluded. The probability of starting home dialysis between 1997 through 2016 was evaluated in time periods of 5 years, using logistic regression analysis. Home dialysis was defined as start with peritoneal dialysis or home haemodialysis, or transfer to either within 2 years after dialysis start. A logistic multilevel model was used to adjust for clustering at patient level. The cumulative incidence function of start of home dialysis in incident patients was estimated with a competing risk model with recovery of kidney function, kidney transplantations, and all-cause mortality as competing events. All analyses were stratified for age categories at dialysis start: 20-44 years, 45-64 years, 65-74 years and ≥75 years.

Results

A total of 33,340 dialysis episodes in 31,569 patients were evaluated. Between 1997 and 2016, mean age at start of dialysis treatment increased from 62.5±14.0 to 65.5±14.5 years in in-centre haemodialysis patients, whereas it increased from 51.9±15.1 to 62.5±14.6 years in home dialysis patients. In patients &lt; 65 years, the probability of starting home dialysis was significantly lower during each 5-year period compared to the previous period, and kidney transplantation occurred more often. In patients ≥ 65 years, incidence of home dialysis remained constant, whereas mortality decreased.

Conclusion

In patients &lt; 65 years, the overall probability of starting home dialysis declined consistently over the past 20 years. The age of home dialysis patients increased more rapidly than that of in-centre dialysis patients, implying that pre-dialysis education and organization of home dialysis must be adapted to the needs of the elderly patient. These developments have a significant impact on the organisation of home dialysis for patients with ESKD.

Renal replacement therapy in Europe: a summary of the 2013 ERA-EDTA Registry Annual Report with a focus on diabetes mellitus

Background

This article provides a summary of the 2013 European Renal Association–European Dialysis and Transplant Association (ERA-EDTA) Registry Annual Report (available at http://www.era-edta-reg.org), with a focus on patients with diabetes mellitus (DM) as the cause of end-stage renal disease (ESRD).

Methods

In 2015, the ERA-EDTA Registry received data on renal replacement therapy (RRT) for ESRD from 49 national or regional renal registries in 34 countries in Europe and bordering the Mediterranean Sea. Individual patient data were provided by 31 registries, while 18 registries provided aggregated data. The total population covered by the participating registries comprised 650 million people.

Results

In total, 72 933 patients started RRT for ESRD within the countries and regions reporting to the ERA-EDTA Registry, resulting in an overall incidence of 112 per million population (pmp). The overall prevalence on 31 December 2013 was 738 pmp (n = 478 990). Patients with DM as the cause of ESRD comprised 24% of the incident RRT patients (26 pmp) and 17% of the prevalent RRT patients (122 pmp). When compared with the USA, the incidence of patients starting RRT pmp secondary to DM in Europe was five times lower and the incidence of RRT due to other causes of ESRD was two times lower. Overall, 19 426 kidney transplants were performed (30 pmp). The 5-year adjusted survival for all RRT patients was 60.9% [95% confidence interval (CI) 60.5–61.3] and 50.6% (95% CI 49.9–51.2) for patients with DM as the cause of ESRD.

Vitamin D receptor activator and dietary sodium restriction to reduce residual urinary albumin excretion in chronic kidney disease (ViRTUE study): rationale and study protocol

Optimal albuminuria reduction is considered essential to halting chronic kidney disease (CKD) progression. Both vitamin D receptor activator (VDRA) treatment and dietary sodium restriction potentiate the efficacy of renin-angiotensin-aldosterone-system (RAAS) blockade to reduce albuminuria. The ViRTUE study addresses whether a VDRA in combination with dietary sodium restriction provides further albuminuria reduction in non-diabetic CKD patients on top of RAAS blockade. The ViRTUE study is an investigator-initiated, prospective, multi-centre, randomized, double-blind (paricalcitol versus placebo), placebo-controlled trial targeting stage 1-3 CKD patients with residual albuminuria of >300 mg/day due to non-diabetic glomerular disease, despite angiotensin-converting enzyme inhibitor or angiotensin receptor blocker use. During run-in, all subjects switched to standardized RAAS blockade (ramipril 10 mg/day) and blood pressure titrated to <140/90 mmHg according to a standardized protocol. Eligible patients are subsequently enrolled and undergo four consecutive study periods in random order of 8 weeks each: (i) paricalcitol (2 µg/day) combined with a liberal sodium diet (∼200 mmol Na(+)/day, i.e. mean sodium intake in the general population), (ii) paricalcitol (2 µg/day) combined with dietary sodium restriction (target: 50 mmol Na(+)/day), (iii) placebo combined with a liberal sodium diet and (iv) placebo combined with dietary sodium restriction. Data are collected at the end of each study period. The primary outcome is 24-h urinary albumin excretion. Secondary study outcomes are blood pressure, renal function (estimated glomerular filtration rate), plasma renin activity and, in a sub-population (N = 9), renal haemodynamics (measured glomerular filtration rate and effective renal plasma flow). A sample size of 50 patients provides 90% power to detect a 23% reduction in albuminuria, assuming a 25% dropout rate. Further reduction of residual albuminuria by combination of VDRA treatment and sodium restriction during single-agent RAAS-blockade will justify long-term studies on cardiorenal outcomes and safety.

CLINICAL TRIAL REGISTRATION

NTR2898 (Dutch trial register).

Elevated N-terminal pro-brain natriuretic peptide levels predict an enhanced anti-hypertensive and anti-proteinuric benefit of dietary sodium restriction and diuretics, but not angiotensin receptor blockade, in proteinuric renal patients

BACKGROUND

Renin-angiotensin aldosterone system (RAAS) blockade only partly reduces blood pressure, proteinuria and renal and cardiovascular risk in chronic kidney disease (CKD) but often requires sodium targeting [i.e. low sodium diet (LS) and/or diuretics] for optimal efficacy. However, both under- and overtitration of sodium targeting can easily occur. We evaluated whether N-terminal pro-brain natriuretic peptide (NT-proBNP), a biomarker of volume expansion, predicts the benefits of sodium targeting in CKD patients.

METHODS

In a cross-over randomized controlled trial, 33 non-diabetic CKD patients (proteinuria 3.8 ± 0.4 g/24 h, blood pressure 143/86 ± 3/2 mmHg, creatinine clearance 89 ± 5 mL/min) were treated during 6-week periods with placebo, angiotensin receptor blockade (ARB; losartan 100 mg/day) and ARB plus diuretics (losartan 100 mg/day plus hydrochlorothiazide 25 mg/day), combined with LS (93 ± 52 mmol Na(+)/24 h) and regular sodium diet (RS; 193 ± 62 mmol Na(+)/24 h, P < 0.001 versus LS), in random order. As controls, 27 healthy volunteers were studied.

RESULTS

NT-proBNP was elevated in patients during placebo + RS [90 (60-137) versus 35 (27-45) pg/mL in healthy controls, P = 0.001]. NT-proBNP was lowered by LS, ARB and diuretics and was normalized by ARB + diuretic + LS [39 (26-59) pg/mL, P = 0.65 versus controls]. NT-proBNP levels above the upper limit of normal (>125 pg/mL) predicted a larger reduction of blood pressure and proteinuria by LS and diuretics but not by ARB, during all steps of the titration regimen.

CONCLUSIONS

Elevated NT-proBNP levels predict an enhanced anti-hypertensive and anti-proteinuric benefit of sodium targeting, but not RAAS blockade, in proteinuric CKD patients. Importantly, this applies to the untreated condition, as well as to the subsequent treatment steps, consisting of RAAS blockade and even RAAS blockade combined with diuretics. NT-proBNP can be a useful tool to identify CKD patients in whom sodium targeting can improve blood pressure and proteinuria.