Assessing the Validity of Surrogate Outcomes for ESRD: A Meta-Analysis

Shrunken Pore Syndrome Is Associated with Renal Function Decline in Female Patients with Kidney Diseases

Background

Shrunken pore syndrome (SPS) represents selective impairment of kidney filtration of low-molecular-weight molecules between 1 and 30 kDa and has been related to outcomes including morbidity, mortality, and cardiovascular events. However, the prevalence and kidney outcomes of SPS have not been investigated in patients with IgA nephropathy (IgAN) and membranous nephropathy (MN).

Methods

We retrospectively collected information of 536 patients including 414 with IgAN and 122 with MN. SPS was mainly defined by cystatin C-based eGFR < 70% of creatinine-based eGFR using the CAPA-LM equation pairs, while CKD-EPI equations were also employed in sensitivity analyses. Prevalence rate of SPS and its association with end-stage renal disease (ESRD) or severe eGFR decline (≥50% eGFR reduction or doubling of baseline creatinine) were investigated.

Results

44% (8%) patients were identified as possessing SPS using the CAPA-LM definition. ESRD happened in 24 patients during the average follow-up period of 27.7 months. Despite dramatic increase of incidence rate of ESRD for SPS, significant hazard ratio (HR) only existed in IgAN patients after multivariable adjustment (HR: 8.35, 95% CI: 2.10~33.26), but lost significance in sensitivity analyses. 36 patients were determined as having experienced severe eGFR decline after excluding transient creatinine fluctuation. SPS was associated with severe eGFR decline by Kaplan-Meier survival analyses in the overall population as well as the IgAN, MN, male, and female subpopulations, which remained significant in multivariable adjustments in all groups except IgAN. However, only in female patients the association between SPS and eGFR decline remained significant in all the sensitivity analyses.

Conclusions

SPS was independently associated with eGFR decline in female patients with IgAN and MN.

The importance of addressing multiple risk markers in type 2 diabetes: Results from the LEADER and SUSTAIN 6 trials

AIMS

To investigate to what extent multiple risk marker improvements confer lower risk of cardiovascular and kidney complications in a contemporary type 2 diabetes population.

MATERIALS AND METHODS

Post-hoc analysis of the LEADER (n = 8638; median follow-up 3.8 years) and SUSTAIN 6 (n = 3040; median follow-up 2.1 years) cardiovascular outcome trials. Participants were those with baseline and year-1 assessment of at least one of the parameters of interest; we pooled the liraglutide-/semaglutide- and placebo-treated groups and categorized them by number of risk markers with clinically relevant improvements after 1 year of study participation. We investigated risk of major adverse cardiovascular events (MACE), expanded MACE, cardiovascular death and nephropathy. Predefined clinically relevant changes: body weight loss ≥5%; reductions in: glycated haemoglobin ≥1%, systolic blood pressure ≥5 mmHg and low-density lipoprotein cholesterol ≥0.5 mmol/L; estimated glomerular filtration rate change ≥0 ml/min/1.73 m² and urinary albumin-to-creatinine ratio change ≥30% of baseline value. Cox regression analysed risk of outcomes adjusted for baseline risk marker levels and treatment group and stratified by trial.

RESULTS

Participants with two, three, or four or more improved risk markers versus participants with no risk marker improvement had reduced risk of expanded MACE [hazard ratio (95% confidence interval) 0.80 (0.67-0.96); 0.80 (0.66-0.97); 0.82 (0.66-1.02)], cardiovascular death [0.66 (0.45-0.96), 0.67 (0.45-0.99), 0.60 (0.38-0.94)] and nephropathy [0.71 (0.52-0.97), 0.48 (0.34-0.68), 0.43 (0.29-0.65)].

CONCLUSIONS

In persons with type 2 diabetes, improvements in ≥2 risk markers conferred cardiovascular risk reduction versus none or one improved risk marker. The nephropathy risk decreased with improvement in more risk markers. These findings stress the importance of multifactorial interventions targeting all risk markers.

Kidney Age Index (KAI): A novel age-related biomarker to estimate kidney function in patients with diabetic kidney disease using machine learning

BACKGROUND AND OBJECTIVE

With aging, patients with diabetic kidney disease (DKD) show progressive decrease in kidney function. We investigated whether the deviation of biological age (BA) from the chronological age (CA) due to DKD can be used (denoted as Kidney Age Index; KAI) to quantify kidney function using machine learning algorithms.

METHODS

Three large datasets were used in this study to develop KAI. The machine learning algorithms were trained on PREVEND dataset with healthy subjects (N = 7963) using 13 clinical markers to predict the CA. The trained model was then used to predict the BA of patients with DKD using RENAAL (N = 1451) and IDNT (N = 1706). The performance of four traditional machine learning algorithms were evaluated and the KAI = BA-CA was estimated for each patient.

RESULTS

The neural network model achieved the best performance and predicted the CA of healthy subjects in PREVEND dataset with a mean absolute deviation (MAD) = 6.5 ± 3.5 years and pearson correlation = 0.62. Patients with DKD showed a significant higher KAI of 15.4 ± 11.8 years and 13.6 ± 12.3 years in RENAAL and IDNT datasets, respectively.

CONCLUSIONS

Our findings suggest that for a given CA, patients with DKD shows excess BA when compared to their healthy counterparts due to disease severity. With further improvement, the proposed KAI can be used as a complementary easy-to-interpret tool to give a more inclusive idea into disease state.

Significance of revised criteria for chronic active T cell-mediated rejection in the 2017 Banff classification: Surveillance by 1-year protocol biopsies for kidney transplantation

Diagnostic criteria for chronic active T cell-mediated rejection (CA-TCMR) were revised in the Banff 2017 consensus, but it is unknown whether the new criteria predict graft prognosis of kidney transplantation. We enrolled 406 kidney allograft recipients who underwent a 1-year protocol biopsy (PB) and investigated the diagnostic significance of Banff 2017. Interobserver reproducibility of the 3 diagnosticians showed a substantial agreement rate of 0.68 in Fleiss's kappa coefficient. Thirty-three patients (8%) were classified as CA-TCMR according to Banff 2017, and 6 were previously diagnosed as normal, 12 as acute TCMR, 10 with borderline changes, and 5 as CA-TCMR according to Banff 2015 criteria. Determinant factors of CA-TCMR were cyclosporine use (vs tacrolimus), previous acute rejection, and BK polyomavirus-associated nephropathy. In survival analysis, the new diagnosis of CA-TCMR predicted a composite graft endpoint defined as doubling serum creatinine or death-censored graft loss (log-rank test, P < .001). In multivariate analysis, CA-TCMR was associated with the second highest risk of the composite endpoint (hazard ratio: 5.42; 95% confidence interval, 2.02-14.61; P < .001 vs normal) behind antibody-mediated rejection. In conclusion, diagnosis of CA-TCMR in Banff 2017 may facilitate detecting an unfavorable prognosis of kidney allograft recipients who undergo a 1-year PB.

GFR slope as a surrogate endpoint for CKD progression in clinical trials

PURPOSE OF REVIEW

There is a paucity of therapies for chronic kidney disease (CKD), in part because of the slow nature of the disease which poses challenges in selection of endpoints in randomized controlled trials (RCT). There is increasing evidence for the use of glomerular filtration rate (GFR)-based endpoints either as percentage decline using time-to-event analyses, or as difference in slope between treatment arms. We reviewed the rationale for using surrogate endpoints and optimal methods for their evaluation prior to their use and evidence for GFR-based endpoints and particularly GFR slope as validated surrogate endpoints and considerations for their use in RCTs.

RECENT FINDINGS

In an individual patient meta-analysis of 47 studies (60 620 participants), treatment effects on the clinical endpoint were accurately predicted from treatment effects on 3-year total slope [median R = 0.97 (95% Bayesian confidence interval (BCI), 0.78-1.00] and on the chronic slope [R = 0.96 (95% BCI, 0.63-1.00)]. In a simulation study, GFR slope substantially reduced the required sample size and duration of follow-up compared to the clinical endpoint given high baseline GFR and absence of acute treatment effect. In the presence of acute effect, results were more complicated.

SUMMARY

GFR decline is accepted, and GFR slope is being considered, by regulatory authorities as a validated surrogate endpoint for CKD RCTs.

The short-term effects of angiotensin II receptor blockers on albuminuria and renal function in Korean patients

Each angiotensin II receptor blocker (ARB) asserts independent molecular effects. No study has compared the renoprotective potency of different types of ARBs in Korea. This study evaluated the differences among medications for treating albuminuria. Data were obtained from electronic medical records of adult patients who underwent albuminuria test and received treatment with either angiotensin-converting enzyme inhibitors (ACEIs) or ARBs between January 2009 and June 2016. Patients' albuminuria and renal function data were observed for three months after treatment initiation. In total, 1475 patients were included. Patients treated with ACEIs had no significant changes in albuminuria (from 127.7 ± 55.1 mg/g to 46.7 ± 18.7 mg/g, P = .127), but those treated with ARBs showed significant improvement (from 491.2 ± 33.2 mg/g to 372.0 ± 28.0 mg/g, P < .001). The ARB group had significantly more patients with normal albuminuria after treatment (from 55.8% to 59.3% for normal albuminuria, from 16.7% to 18.5% for moderately increased albuminuria and from 27.5% to 22.2% for severely increased albuminuria, P = .005), but renal function did not change significantly. Subgroup analysis of ARB types showed that candesartan (from 712.5 ± 71.1 to 489.8 ± 57.8 mg/g, P < .001) and irbesartan (from 522.6 ± 65.7 to 352.6 ± 54.3 mg/g, P < .001) had significant effects. Candesartan improved albuminuria in patients older than 60 years (from 506.9 ± 84.2 to 371.9 ± 70.6 mg/g, P = .004) and irbesartan improved albuminuria in patients with glomerular filtration rate <60 (from 551.6 ± 100.0 to 392.4 ± 76.2, P = .007). Only irbesartan and candesartan could reduce albuminuria, suggesting that all ARBs do not have the same outcome. This indicates the importance of optimizing ARB selection, considering both patient condition and organ-specific characteristics of medications.

Effect of Vitamin D and Omega-3 Fatty Acid Supplementation on Kidney Function in Patients With Type 2 Diabetes: A Randomized Clinical Trial

IMPORTANCE

Chronic kidney disease (CKD) is a common complication of type 2 diabetes that can lead to end-stage kidney disease and is associated with high cardiovascular risk. Few treatments are available to prevent CKD in type 2 diabetes.

OBJECTIVE

To test whether supplementation with vitamin D3 or omega-3 fatty acids prevents development or progression of CKD in type 2 diabetes.

DESIGN, SETTING, AND PARTICIPANTS

Randomized clinical trial with a 2 × 2 factorial design conducted among 1312 adults with type 2 diabetes recruited between November 2011 and March 2014 from all 50 US states as an ancillary study to the Vitamin D and Omega-3 Trial (VITAL), coordinated by a single center in Massachusetts. Follow-up was completed in December 2017.

INTERVENTIONS

Participants were randomized to receive vitamin D3 (2000 IU/d) and omega-3 fatty acids (eicosapentaenoic acid and docosahexaenoic acid; 1 g/d) (n = 370), vitamin D3 and placebo (n = 333), placebo and omega-3 fatty acids (n = 289), or 2 placebos (n = 320) for 5 years.

MAIN OUTCOMES AND MEASURES

The primary outcome was change in glomerular filtration rate estimated from serum creatinine and cystatin C (eGFR) from baseline to year 5.

RESULTS

Among 1312 participants randomized (mean age, 67.6 years; 46% women; 31% of racial or ethnic minority), 934 (71%) completed the study. Baseline mean eGFR was 85.8 (SD, 22.1) mL/min/1.73 m2. Mean change in eGFR from baseline to year 5 was -12.3 (95% CI, -13.4 to -11.2) mL/min/1.73 m2 with vitamin D3 vs -13.1 (95% CI, -14.2 to -11.9) mL/min/1.73 m2 with placebo (difference, 0.9 [95% CI, -0.7 to 2.5] mL/min/1.73 m2). Mean change in eGFR was -12.2 (95% CI, -13.3 to -11.1) mL/min/1.73 m2 with omega-3 fatty acids vs -13.1 (95% CI, -14.2 to -12.0) mL/min/1.73 m2 with placebo (difference, 0.9 [95% CI, -0.7 to 2.6] mL/min/1.73 m2). There was no significant interaction between the 2 interventions. Kidney stones occurred among 58 participants (n = 32 receiving vitamin D3 and n = 26 receiving placebo) and gastrointestinal bleeding among 45 (n = 28 receiving omega-3 fatty acids and n = 17 receiving placebo).

CONCLUSIONS AND RELEVANCE

Among adults with type 2 diabetes, supplementation with vitamin D3 or omega-3 fatty acids, compared with placebo, resulted in no significant difference in change in eGFR at 5 years. The findings do not support the use of vitamin D or omega-3 fatty acid supplementation for preserving kidney function in patients with type 2 diabetes.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01684722.

Cause-specific mortality in the general population with transient dipstick-proteinuria

Recently, changes in urinary albumin and in GFR have been recognized as risk factors for the development of end-stage kidney disease and mortality. Though most clinical epidemiology studies of chronic kidney disease (CKD) used renal function and proteinuria at baseline alone, definitive diagnosis of CKD with multiple measurements intensifies the differences in the risk for mortality between the CKD and non-CKD populations. We hypothesized that a transient diagnosis of proteinuria and reduced renal function each indicate a significantly higher mortality compared to definitive non-CKD as the negative control and lower mortality compared with definitive CKD as the positive control. The present longitudinal study evaluated a general-population cohort of 338,094 persons who received annual health checkups, with a median 4.3-year study period. There were 2,481 deaths, including 510 CVD deaths (20.6%) and 1,328 cancer deaths (53.5%), and mortality risk was evaluated for transient proteinuria and for transiently reduced renal function. The hazard ratios (HRs) for all-cause mortality and cancer mortality were not significant, but that for cardiovascular mortality was significantly higher for transient proteinuria (HR, 1.94 [95% confidence interval, 1.27–2.96] in men and 2.78 [1.50–5.16] in women). On the other hand, transiently reduced renal function was not significant for either cardiovascular mortality risk or cancer mortality risk. We surmise that this is the first study of the mortality risk of transient dipstick proteinuria in a large general-population cohort with cause-specific death registration. Transiently positive proteinuria appears to be a significant risk specifically for cardiovascular mortality compared with definitely negative for proteinuria.

A collaborative, individual-level analysis compared longitudinal outcomes across the International Network of Chronic Kidney Disease (iNETCKD) cohorts

Rates of chronic kidney disease (CKD) progression, end stage kidney disease (ESKD), all-cause mortality, and cardiovascular (CVD) events among individuals with CKD vary widely across countries. Well-characterized demographic, comorbidity, and laboratory markers captured for prospective cohorts may explain, in part, such differences. To investigate whether core characteristics of individuals with CKD explain differences in rates of outcomes, we conducted an individual-level analysis of eight studies that are part of iNET-CKD, an international network of CKD cohort studies. Overall, the rate of CKD progression was 40 events/1000 person-year (95% confidence interval 39 - 41), 28 (27 - 29) for ESKD, 41 (40 - 42) for death, and 29 (28 - 30) for CVD events. However, standardized rates were highly heterogeneous across studies (over 92.5%). Interactions by study group on the association between baseline characteristics and outcomes were then identified. For example, the adjusted hazard ratio for CKD progression was 0.44 (95% confidence interval 0.35 - 0.56) for women vs. men among the Japanese (CKD-JAC), while it was 0.66 (0.59 - 0.75) among the Uruguayan (NRHP). The adjusted hazard ratio for ESKD was 2.02 (95% CI 1.88 - 2.17) per 10 units lower baseline eGFR among Americans (CRIC), while it was 3.01 (2.57 - 3.53) among Canadians (CanPREDDICT) (significant interaction for comparisons across all studies). The risks of CKD progression, ESKD, death, and CVD vary across countries even after accounting for the distributions of age, sex, comorbidities, and laboratory markers. Thus, our findings support the need for a better understanding of specific factors in different populations that explain this variation.

Change in Albuminuria and GFR as End Points for Clinical Trials in Early Stages of CKD: A Scientific Workshop Sponsored by the National Kidney Foundation in Collaboration With the US Food and Drug Administration and European Medicines Agency

The US Food and Drug Administration (FDA) and European Medicines Agency (EMA) are currently willing to consider a 30% to 40% glomerular filtration rate (GFR) decline as a surrogate end point for kidney failure for clinical trials of kidney disease progression under appropriate conditions. However, these end points may not be practical for early stages of kidney disease. In March 2018, the National Kidney Foundation sponsored a scientific workshop in collaboration with the FDA and EMA to evaluate changes in albuminuria or GFR as candidate surrogate end points. Three parallel efforts were presented: meta-analyses of observational studies (cohorts), meta-analyses of clinical trials, and simulations of trial design. In cohorts, after accounting for measurement error, relationships between change in urinary albumin-creatinine ratio (UACR) or estimated GFR (eGFR) slope and the clinical outcome of kidney disease progression were strong and consistent. In trials, the posterior median R² of treatment effects on the candidate surrogates with the clinical outcome was 0.47 (95% Bayesian credible interval [BCI], 0.02-0.96) for early change in UACR and 0.72 (95% BCI, 0.05-0.99) when restricted to baseline UACR>30mg/g, and 0.97 (95% BCI, 0.78-1.00) for total eGFR slope at 3 years and 0.96 (95% BCI, 0.63-1.00) for chronic eGFR slope (ie, the slope excluding the first 3 months from baseline, when there might be acute changes in eGFR). The magnitude of the relationships of changes in the candidate surrogates with risk for clinical outcome was consistent across cohorts and trials: a UACR reduction of 30% or eGFR slope reduction by 0.5 to 1.0mL/min/1.73m² per year were associated with an HR of ∼0.7 for the clinical outcome in cohorts and trials. In simulations, using GFR slope as an end point substantially reduced the required sample size and duration of follow-up compared with the clinical end point when baseline eGFR was high, treatment effects were uniform, and there was no acute effect of the treatment. We conclude that both early change in albuminuria and GFR slope fulfill criteria for surrogacy for use as end points in clinical trials for chronic kidney disease progression under certain conditions, with stronger support for change in GFR than albuminuria. Implementation requires understanding conditions under which each surrogate is likely to perform well and restricting its use to those settings.

UA promotes epithelial‑mesenchymal transition in peritoneal mesothelial cells

Long‑term peritoneal dialysis is often limited or interrupted due to the development and progression of peritoneal fibrosis. Accumulating evidence suggests that epithelial‑mesenchymal transition (EMT) is a major component of peritoneal injury associated with peritoneal fibrosis in the end stage of renal disease; however, at present, the underlying mechanisms remain unclear. Thus, in the present study, uric acid (UA)‑induced EMT of peritoneal mesothelial cells was investigated by western‑blot and immunofluorescence staining. The results revealed that peritoneal mesothelial cells stimulated with UA underwent EMT, as demonstrated by the decreased expression of epithelial markers (E‑cadherin) and an increased expression of mesenchymal markers (α‑smooth muscle actin and vimentin). Additionally, it was reported that UA could facilitate the progression of EMT of peritoneal mesothelial cells via EMT transcription pathways, including transforming growth factor‑β1/mothers against decapentaplegic homolog 3 and P38/mitogen‑activated protein kinase by western‑blot and reverse transcription semi‑quantitative polymerase chain reaction. The results of the present study suggest that UA could promote EMT and may contribute to peritoneal chronic disease. Furthermore, the data obtained suggest that the levels of blood UA may account for the development of EMT; thus, lowering the levels of blood UA may be beneficial to inhibit the occurrence and development of peritoneal fibrosis.

Changes in albuminuria and renal outcome in patients with type 2 diabetes and hypertension: a real-life observational study

OBJECTIVES

To assess the predictive role of changes in albuminuria on the loss of renal function under antihypertensive treatment in patients with type 2 diabetes (T2D).

METHODS

Clinical records from a total of 12 611 patients with hypertension and T2D, attending 100 antidiabetic centers in Italy, with normal estimated glomerular filtration rate (eGFR) at baseline and regular visits during a 4-year period were retrieved and analyzed. We assessed the association between changes in albuminuria status during a 1-year baseline period and time updated blood pressure (BP) and eGFR loss over the subsequent 4-year follow-up.

RESULTS

Mean age at baseline was 65 ± 9 years, known duration of diabetes11 ± 8 years, eGFR 85 ± 13 ml/min and BP 142 ± 17/81 ± 9 mmHg. Patients with persistent albuminuria showed the highest 4-year risk of eGFR loss more than 30% from baseline or onset of stage 3 chronic kidney disease (eGFR < 60 ml/min) as compared with those with persistent normal albuminuria (odds ratio 2.00, confidence interval 1.71-2.34; P < 0.001). Female sex, age, disease duration, BMI, low baseline eGFR, lipid profile, the number of antihypertensive drugs and variations in albuminuria status were associated with renal risk in the whole study population. Furthermore, lower time updated BP values and the use of renin-angiotensin-aldosterone-system-inhibitors were related to the occurrence of renal endpoints only in the subgroup of patients without albuminuria.

CONCLUSION

In patients with hypertension and T2D under real-life clinical conditions, changes in albuminuria parallel changes of renal risk. Albuminuria status could be a guide to optimize therapeutic strategy.

Combination of Changes in Estimated GFR and Albuminuria and the Risk of Major Clinical Outcomes

BACKGROUND AND OBJECTIVES

Whether combining changes in eGFR and urine albumin-to-creatinine ratio (UACR) is more strongly associated with outcomes compared with either change alone is unknown.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We analyzed 8766 patients with type 2 diabetes in the Action in Diabetes and Vascular Disease: Preterax and Diamicron Modified Release Controlled Evaluation Observational (ADVANCE-ON) study. Changes in eGFR and UACR (baseline to 2 years) were defined as ≥40% decrease, minor change, and ≥40% increase. The primary outcome was the composite of major macrovascular (nonfatal or fatal myocardial infarction, nonfatal or fatal stroke, or cardiovascular death), major kidney events (requirement for kidney replacement therapy or kidney death), and all-cause mortality.

RESULTS

Over a median of 7.7 years of follow-up, 2191 primary outcomes were recorded. Strong linear associations between eGFR and UACR changes and subsequent risk of the outcome were observed. For eGFR, the hazard ratios were 1.58 (95% confidence interval [95% CI], 1.27 to 1.95) for a decrease ≥40% and 0.82 for an increase ≥40% (95% CI, 0.64 to 1.04) compared with minor change. For UACR, the hazard ratios were 0.96 (95% CI, 0.85 to 1.07) for a decrease ≥40% and 1.32 (95% CI, 1.19 to 1.46) for ≥40% increase compared with minor change. Compared with dual minor changes, both an eGFR decrease ≥40% and a UACR increase ≥40% had 2.31 (95% CI, 1.67 to 3.18) times the risk of the outcome, with evidence of interaction between the two markers.

CONCLUSIONS

Clinically meaningful decreases in eGFR and increases in UACR over 2 years, independently and in combination, were significantly associated with higher risk of major clinical outcomes.

Impact of Using Alternative Graft Function Endpoints: A Secondary Analysis of a Kidney Transplant Trial

Supplemental digital content is available in the text.

Background

Nephrology trials assessing the impact of interventions on “standard” outcomes, such as doubling of creatinine, end-stage renal disease (ESRD), and/or death, are difficult to conduct given the time required for endpoints to accrue. The objective of this study was to determine if using lesser declines in kidney function would alter the interpretation of a previous randomized controlled trial.

Methods

This study was a secondary analysis of a kidney transplant trial comparing the use of a 40% or greater, 30% or greater, or 20% or greater decline in estimated glomerular filtration rate (eGFR) as a substitute for doubling of serum creatinine. Declines in eGFR were determined relative to baseline. This trial enrolled 212 kidney transplant patients with proteinuria and assessed the clinical impact of ramipril versus placebo on a primary outcome of doubling of serum creatinine, ESRD, or death. In this analysis, the declines in eGFR replaced doubling of creatinine in the composite endpoint.

Results

Mean trial follow-up was 41 months. A time-to-event composite of death, ESRD, or a 40% or greater, 30% or greater, or 20% or greater eGFR decline occurred in 45 (26 placebo vs 19 ramipril), 68 (35 vs 33), and 99 (50 vs 49) patients, respectively. Substituting these eGFR declines for doubling of serum creatinine resulted in an increase of 12, 35, and 66 endpoints compared with the original trial. In all 3 eGFR declines, ramipril treatment was not associated with any statistically significant differences despite the increase in events.

Conclusions

Substituting doubling of serum creatinine for lesser eGFR percentage decline thresholds did not alter trial interpretation but did increase the number of events.

Antihypertensive treatment and renal protection: Is there a J-curve relationship?

A bidirectional relationship between hypertension and kidney disease, with one exacerbating the effect of the other, is well established. Elevated blood pressure (BP) is a well-recognized, modifiable risk factor for cardiovascular (CV) disease as well as for development and progression of chronic kidney disease and, therefore, the identification of optimal BP target is a key issue in the management of renal patients. Recent large trials and real life cohort studies have indicated that below a definite BP value renal protection seems to plateau and too low levels may even be associated with a paradoxical increase in renal morbidity, thus reviving the debate about the so called BP -renal function J-curve relationship. Existing evidence supports a systolic target around 130 mm Hg to combine both renal and CV protection and possibly lower levels in the presence of overt proteinuria.

Change in Proteinuria or Albuminuria as a Surrogate for Cardiovascular and Other Major Clinical Outcomes: A Systematic Review and Meta-analysis

BACKGROUND

There is ongoing controversy around the surrogacy of proteinuria or albuminuria, particularly for cardiovascular (CV) outcomes, which remain the leading cause of morbidity and mortality among patients with chronic kidney disease. We performed a systematic review and meta-analysis of the literature to assess the surrogacy of changing proteinuria or albuminuria for CV events, end-stage renal disease (ESRD), and all-cause mortality.

METHODS

CENTRAL, EMBASE, and MEDLINE were searched (from inception to October 2017). All randomized controlled trials in adults that reported change in proteinuria or albuminuria and ≥ 10 CV, ESRD, or all-cause mortality events were included. We calculated treatment effect ratios (TERs), defined as the ratio of the treatment effect on a clinical outcome and the effect on the change in the surrogate outcome. TERs close to 1 indicate greater agreement between the clinical outcome and changing proteinuria or albuminuria.

RESULTS

Thirty-six trials were included in the meta-analysis. We observed inconsistent treatment effects for proteinuria and CV events (20 trials; TER 1.11 [95% confidence interval (CI), 1.01-1.22]) with moderate heterogeneity (I² = 51%, P = 0.005). Treatment effects on proteinuria or albuminuria were also inconsistent with the effects on all-cause mortality (21 trials; TER 1.17 [95% CI, 1.07-1.28]; I² = 35%, P for heterogeneity = 0.06), although they were similar with the effects on ESRD (23 trials; TER 0.99 [95% CI, 0.88-1.13]; I² = 9%, P for heterogeneity = 0.337).

CONCLUSIONS

Change in proteinuria or albuminuria might be a suitable surrogate outcome for ESRD. However, overall treatment effects on these potential surrogates are inconsistent and overestimate the treatment effects on CV events and all-cause mortality.

Normal-range albuminuria in healthy subjects increases over time in association with hypertension and metabolic outcomes

Albuminuria is a prognostic factor for mortality and cardiovascular events, even at low levels. Changes in albumin excretion are associated with end-stage renal disease and hypertension (HTN) in cohorts including high-risk participants. We aimed to investigate the evolvement of albumin excretion in healthy individuals with normal kidney function and normoalbuminuria, and possible associations with HTN and metabolic outcomes. The study cohort consisted of 1967 healthy adults with normal kidney function (estimated glomerular filtration rate ≥ 90 mL/min/1.73 m²; urine albumin to creatinine ratio [ACR] < 30 mg/g). Delta ACR slope was calculated as ACR difference between two consecutive visits divided by the time interval. During a mean follow-up period of 93.8 months, mean delta ACR slope was 0.27 ± 3.29 mg/g/year and was higher in participants with age >40 years, obesity, a high waist circumference, higher baseline ACR, HTN, prediabetes, and metabolic syndrome. Delta ACR slopes in the upper quartile predicted diabetes (OR = 1.31, P = .027) and albuminuria (4.34, P < .001). Upper quartile of ACR slopes correlated with a higher risk for new-onset HTN (1.249, P = .031). Delta systolic and diastolic blood pressures were associated with ACR slopes in addition to age, body mass index, and baseline ACR. In conclusion, accelerated change in ACR correlates with HTN and diabetes in healthy individuals with normal kidney function and normoalbuminuria.

Urine Trefoil Factors as Prognostic Biomarkers in Chronic Kidney Disease

Introduction

Trefoil factor family (TFF) peptides are increased in serum and urine in patients with chronic kidney disease (CKD). However, whether the levels of TFF predict the progression of CKD remains to be elucidated.

Methods

We determined the TFF levels using peptide-specific ELISA in spot urine samples and performed a prospective cohort study. The association between the levels of urine TFFs and other urine biomarkers as well as the renal prognosis was analyzed in 216 CKD patients (mean age: 53.7 years, 47.7% female, 56.9% with chronic glomerulonephritis, and mean eGFR: 58.5 ml/min/1.73 m²).

Results

The urine TFF1 and TFF3 levels significantly increased with the progression of CKD stages, but not the urine TFF2 levels. The TFF1 and TFF3 peptide levels predicted the progression of CKD ≥ stage 3b by ROC analysis (AUC 0.750 and 0.879, resp.); however, TFF3 alone predicted CKD progression in a multivariate logistic regression analysis (odds ratio 3.854, 95% confidence interval 1.316–11.55). The Kaplan-Meier survival curves demonstrated that patients with a higher TFF1 and TFF3 alone, or in combination with macroalbuminuria, had a significantly worse renal prognosis.

Conclusion

The data suggested that urine TFF peptides are associated with renal progression and the outcomes in patients with CKD.

Estimated glomerular filtration rate and the risk-benefit profile of intensive blood pressure control amongst nondiabetic patients: a post hoc analysis of a randomized clinical trial

BACKGROUND

The Systolic Blood Pressure Intervention Trial (SPRINT; ClinicalTrials.gov, NCT01206062) reported reduced cardiovascular events by intensive blood pressure (BP) control amongst hypertensive patients without diabetes. However, the risk-benefit profile of intensive BP control may differ across estimated glomerular filtration rate (eGFR) levels.

METHODS

This is a post hoc analysis of the SPRINT. Nondiabetic hypertensive adults (n = 9361) with eGFR >20 mL per min per 1.73 m² were enrolled from 102 US facilities between November 2010 and March 2013 and were followed up until August 2015 (median follow-up, 3.26 years). Patients were randomly assigned to either a systolic BP target of <120 or <140 mmHg (for intensive or standard treatment, respectively). The outcomes of interests were the development of (i) fatal and nonfatal major cardiovascular events and (ii) acute kidney injury (AKI).

RESULTS

The cardiovascular benefit from intensive treatment was attenuated with lower eGFR (P_interaction  = 0.019), whereas eGFR did not modify the adverse effect on AKI (P_interaction  = 0.179). Amongst 891 participants with eGFR <45 mL per min per 1.73 m² , intensive treatment did not reduce the cardiovascular outcome (54/446 vs. 54/445 events in the standard group, respectively; hazard ratio [HR], 0.92; 95% CI, 0.62-1.38) with an absolute rate difference (ARD) of -0.02 (95% CI, -0.07 to +0.03) per 100 patient-years, whereas it increased AKI (62/446 vs. 38/445 events in the standard group; HR, 1.73; 95% CI, 1.12-2.66) with an ARD of +1.93 (95% CI, +1.88 to +1.97) per 100 patient-years.

CONCLUSIONS

Intensive BP control may provide little or no benefit and even be harmful for patients with moderate-to-advanced chronic kidney disease.

Standardised Outcomes in Nephrology-Polycystic Kidney Disease (SONG-PKD): study protocol for establishing a core outcome set in polycystic kidney disease

Background

Autosomal dominant polycystic kidney disease (ADPKD) is the most common potentially life threatening inherited kidney disease and is responsible for 5–10% of cases of end-stage kidney disease (ESKD). Cystic kidneys may enlarge up to 20 times the weight of a normal kidney due to the growth of renal cysts, and patients with ADPKD have an increased risk of morbidity, premature mortality, and other life-time complications including renal and hepatic cyst and urinary tract infection, intracranial aneurysm, diverticulosis, and kidney pain which impair quality of life. Despite some therapeutic advances and the growing number of clinical trials in ADPKD, the outcomes that are relevant to patients and clinicians, such as symptoms and quality of life, are infrequently and inconsistently reported. This potentially limits the contribution of trials to inform evidence-based decision-making. The Standardised Outcomes in Nephrology—Polycystic Kidney Disease (SONG-PKD) project aims to establish a consensus-based set of core outcomes for trials in PKD (with an initial focus on ADPKD but inclusive of all stages) that patients and health professionals identify as critically important.

Methods

The five phases of SONG-PKD are: a systematic review to identify outcomes that have been reported in existing PKD trials; focus groups with nominal group technique with patients and caregivers to identify, rank, and describe reasons for their choices; qualitative stakeholder interviews with health professionals to elicit individual values and perspectives on outcomes for trials involving patients with PKD; an international three-round Delphi survey with all stakeholder groups (including patients, caregivers, healthcare providers, policy makers, researchers, and industry) to gain consensus on critically important core outcome domains; and a consensus workshop to review and establish a set of core outcome domains and measures for trials in PKD.

Discussion

The SONG-PKD core outcome set is aimed at improving the consistency and completeness of outcome reporting across ADPKD trials, leading to improvements in the reliability and relevance of trial-based evidence to inform decisions about treatment and ultimately improve the care and outcomes for people with ADPKD.

Clinical Practice Guidelines: A Primer on Development and Dissemination

Trustworthy clinical practice guidelines should be based on a systematic review of the literature, provide ratings of the quality of evidence and the strength of recommendations, consider patient values, and be developed by a multidisciplinary panel of experts. The quality of evidence reflects our certainty that the evidence warrants a particular action. Transforming evidence into a decision requires consideration of the quality of evidence, balance of benefits and harms, patients' values, available resources, feasibility of the intervention, acceptability by stakeholders, and effect on health equity. Empirical evidence shows that adherence to guidelines improves patient outcomes; however, adherence to guidelines is variable. Therefore, guidelines require active dissemination and innovative implementation strategies.

Albuminuria changes are associated with subsequent risk of end-stage renal disease and mortality

Current guidelines for chronic kidney disease (CKD) recommend using albuminuria as well as estimated glomerular filtration rate (eGFR) to stage CKD. However, CKD progression is solely defined by change in eGFR with little regard to the risk implications of change in albuminuria. This is an observational study from the Stockholm CREAtinine Measurements (SCREAM) project, a health care utilization cohort from Stockholm, Sweden, with laboratory measures from 2006-2011 and follow-up through December 2012. Included were 31,732 individuals with two or more ambulatory urine albumin to creatinine ratio (ACR) tests. We assessed the association between change in ACR during a baseline period of 1, 2, or 3 years and end-stage renal disease (ESRD) or death. Using a 2-year baseline period, there were 378 ESRD events and 1712 deaths during a median of 3 years of follow-up. Compared to stable ACR, a 4-fold increase in ACR was associated with a 3.08-times (95% confidence interval 2.59 to 3.67) higher risk of ESRD while a 4-fold decrease in ACR was associated with a 0.34-times (0.26 to 0.45) lower risk of ESRD. Similar associations were found in people with and without diabetes mellitus, with and without hypertension, and also when adjusted for the change in eGFR during the same period. The association between change in ACR and mortality was weaker: ACR increase was associated with mortality, but the relationship was largely flat for ACR decline. Results were consistent for 1-, 2-, and 3-year ACR changes. Thus, changes in albuminuria are strongly and consistently associated with the risk of ESRD and death.

An Evidence-Based Approach to Conducting Systematic Reviews on CKD

With the growing need to integrate best evidence to inform clinical care, systematic reviews have continued to flourish. Although this type of review is integral to the synthesis of evidence-based information, systematic reviews are often conducted omitting well-established processes that ensure the validity and replicability of the study; elements of which are integral based on standards developed by the Cochrane Collaboration and the National Academy of Medicine. This review article will share best practices associated with conducting systematic reviews on the topic of CKD using an 8-step process and an evidence-based approach to retrieving and abstracting data. Optimal methods for conducting systematic review searching will be described, including development of appropriate search strategies and utilization of varied resources including databases, grey literature, primary journals, and handsearching. Processes and tools to improve research teams' coordination and efficiency, including integration of systematic review protocols and sophisticated software to streamline data management, will be investigated. In addition to recommended strategies for surveying and synthesizing CKD literature, techniques for maneuvering the complex field of Nephrology will also be explored.

Effect of mineralocorticoid receptor antagonists on proteinuria and progression of chronic kidney disease: a systematic review and meta-analysis

BACKGROUND

Hypertension and proteinuria are critically involved in the progression of chronic kidney disease. Despite treatment with renin angiotensin system inhibition, kidney function declines in many patients. Aldosterone excess is a risk factor for progression of kidney disease. Hyperkalaemia is a concern with the use of mineralocorticoid receptor antagonists. We aimed to determine whether the renal protective benefits of mineralocorticoid antagonists outweigh the risk of hyperkalaemia associated with this treatment in patients with chronic kidney disease.

METHODS

We conducted a meta-analysis investigating renoprotective effects and risk of hyperkalaemia in trials of mineralocorticoid receptor antagonists in chronic kidney disease. Trials were identified from MEDLINE (1966-2014), EMBASE (1947-2014) and the Cochrane Clinical Trials Database. Unpublished summary data were obtained from investigators. We included randomised controlled trials, and the first period of randomised cross over trials lasting ≥4 weeks in adults.

RESULTS

Nineteen trials (21 study groups, 1 646 patients) were included. In random effects meta-analysis, addition of mineralocorticoid receptor antagonists to renin angiotensin system inhibition resulted in a reduction from baseline in systolic blood pressure (-5.7 [-9.0, -2.3] mmHg), diastolic blood pressure (-1.7 [-3.4, -0.1] mmHg) and glomerular filtration rate (-3.2 [-5.4, -1.0] mL/min/1.73 m(2)). Mineralocorticoid receptor antagonism reduced weighted mean protein/albumin excretion by 38.7 % but with a threefold higher relative risk of withdrawing from the trial due to hyperkalaemia (3.21, [1.19, 8.71]). Death, cardiovascular events and hard renal end points were not reported in sufficient numbers to analyse.

CONCLUSIONS

Mineralocorticoid receptor antagonism reduces blood pressure and urinary protein/albumin excretion with a quantifiable risk of hyperkalaemia above predefined study upper limit.

Obesity, Renin-Angiotensin System Blockade and Risk of Adverse Renal Outcomes: A Population-Based Cohort Study

BACKGROUND

Obesity substantially increases the risk of the development of chronic kidney disease. Adipose tissue expresses all of the components of the renin-angiotensin system (RAS), contributing to the high prevalence of hypertension in obese patients and driving renal hyperfiltration and subsequent glomerular injury.

METHODS

We performed a retrospective cohort study using a United Kingdom primary care database, evaluating the effect of time-updated exposure to RAS blockade versus all other antihypertensive medications in obese, hypertensive, non-diabetic patients. We used Cox proportional hazards modeling with and without marginal structural modeling to assess the hazards of developing a primary outcome of 50% reduction in estimated glomerular filtration rate (eGFR) (across 2 consecutive values), end stage renal disease or death.

RESULTS

A total of 219,701 patients met inclusion criteria, with a median 7.2 years of follow-up. Median baseline eGFR was 72.6 ml/min/1.73 m2. Compared to other antihypertensive medications, patients treated with RAS blockade had a modestly elevated hazard of adverse renal outcomes using traditional Cox regression (hazard ratio (HR) 1.04, 95% CI 1.01-1.07) and no significantly increased hazard by marginal structural modeling (HR 1.02, 95% CI 0.97-1.08). Patients treated with RAS blockade had a significantly reduced hazard of incident diabetes, but no significant difference in mortality.

CONCLUSION

This study, conducted in a large real-world cohort, provides evidence that RAS blockade may not provide benefit with regard to longitudinal renal outcomes in obese, hypertensive patients. Further research is needed to elucidate the hemodynamic and renoprotective role of antihypertensive medications in obese patients.

Application of new acute kidney injury biomarkers in human randomized controlled trials

The use of novel biomarkers of acute kidney injury (AKI) in clinical trials may help evaluate treatments for AKI. Here we explore potential applications of biomarkers in simulated clinical trials of AKI using data from the TRIBE-AKI multicenter, prospective cohort study of patients undergoing cardiac surgery. First, in a hypothetical trial of an effective therapy at the time of acute tubular necrosis to prevent kidney injury progression, use of an indirect kidney injury marker such as creatinine compared to a new direct biomarker of kidney injury reduces the proportion of true acute tubular necrosis cases enrolled. The result is a lower observed relative risk reduction with the therapy, and lower statistical power to detect a therapy effect at a given sample size. Second, the addition of AKI biomarkers (interleukin-18 and NGAL) to clinical risk factors as eligibility criteria for trial enrollment in early AKI has the potential to increase the proportion of patients who will experience AKI progression and reduce trial cost. Third, we examine AKI biomarkers as outcome measures for the purposes of identifying therapies that warrant further testing in larger, multicenter, multi-country trials. In the hypothetical trial of lower cardiopulmonary bypass time to reduce the risk of postoperative AKI, the sample size required to detect a reduction in AKI is lower if new biomarkers are used to define AKI rather than serum creatinine. Thus, incorporation of new biomarkers of AKI has the potential to increase statistical power, decrease the sample size, and lower the cost of AKI trials.

Relationship between eGFR Decline and Hard Outcomes after Kidney Transplants

Trials designed to assess the effect of interventions on death and graft failure in kidney transplant recipients are not feasible, because these are predominantly late events. Here, we examined the potential of percentage decline in eGFR as a surrogate for hard outcomes. We obtained deidentified data from the Australia and New Zealand Dialysis and Transplant Registry and studied 7949 transplants performed from 1995 to 2009, including 71,845 patient-years of follow-up, 1121 graft losses, and 1192 deaths. We used adjusted Cox proportional hazards models to determine risks of death or death-censored graft failure related to percentage change in eGFR between years 1 and 3 after transplant. Percentage change in eGFR was modeled as a restricted cubic spline. Rate of eGFR decline associated with exponentially increased risks of graft failure and death. Compared with stable eGFR, a ≥30% decline in eGFR, detected in 10% of patients, strongly associated with subsequent death (hazard ratio, 2.20; 95% confidence interval, 1.87 to 2.60) and death-censored graft failure (hazard ratio, 5.14; 95% confidence interval, 4.44 to 5.95). Decline in eGFR was superior to other surrogates, including acute rejection, doubling of serum creatinine level, and eGFR at year 1 or year 2. We conclude that 30% decline in eGFR between years 1 and 3 after kidney transplant is common and strongly associated with risks of subsequent death and death-censored graft failure, which mirrors findings in CKD. Percentage decline in eGFR should be considered for use as a surrogate outcome in kidney transplant trials.

Effect of Sensor-Augmented Pump Treatment Versus Multiple Daily Injections on Albuminuria: A 1-Year Randomized Study

CONTEXT

The effect of glycemic control on persisting albuminuria remains unclear. Insulin delivery and glucose variability may be important.

OBJECTIVE

This study aimed to investigate the effect of 1-year treatment with sensor-augmented insulin pump (SAP) or multiple daily injections (MDIs) on albuminuria.

DESIGN, PATIENTS, AND METHODS

This was a randomized controlled open-label parallel trial composed of 60 patients with type 1 diabetes with a history of albuminuria and on stable renin-angiotensin system inhibition, were randomly assigned to SAP or MDI. Urine albumin creatinine ratio (UACR) was measured in three urine samples at all visits. Glucose variability and glomerular filtration rate ((51)Cr-EDTA-GFR) were measured at beginning and study end. Using linear mixed model, change in UACR between groups was analyzed as intention to treat.

MAIN OUTCOME MEASURE

Change in UACR was measured.

RESULTS

Fifty-five patients (SAP, n = 26; MDI, n = 29) completed the study. Diabetes duration (mean ± SD, 33 ± 12 y), UACR (geometric mean, 99 mg/g; interquartile range, 37-233 mg/g), (51)Cr-EDTA-GFR (94 ± 22 mL/min/1.73m(2)), glycosylated hemoglobin (HbA1c) (9.0 ± 1.1%), glucose variability (calculated as SD), 4.0 ± 1.0 mmol/l; no-group differences (P ≥ .06 for all). After 1 year, change in UACR was mean, -13%; 95% confidence interval, -39 to 22 with SAP vs mean, 30%; 95% CI, -12 to 92% on MDI treatment (unadjusted P = .051; adjusted for HbA1c, P = .04). HbA1c decreased 1.3 ± 1.0 vs 0.6 ± 1.0% (P = .013), glucose variability decreased 0.9 ± 1.1 vs 0.3 ± 1.0 mmol/L (P = .04), and (51)Cr-EDTA-GFR declined 5.6 ± 9.6 vs 3.4 ± 13 mL/min/1.73m(2) (P = .50) with SAP vs MDI treatment. There were no changes in blood pressure (P ≥ .27).

CONCLUSION

SAP treatment reduced UACR in a randomized controlled trial in type 1 diabetes patients with a history of albuminuria on stable renin-angiotensin system inhibition. Significance was reached after adjustment. SAP treatment reduced HbA1c and glucose variability (calculated as SD).

Glomerular filtration rate decline as a surrogate end point in kidney disease progression trials

Chronic kidney disease (CKD) is strongly associated with increased risks of progression to end-stage kidney disease (ESKD) and mortality. Clinical trials evaluating CKD progression commonly use a composite end point of death, ESKD or serum creatinine doubling. However, due to low event rates, such trials require large sample sizes and long-term follow-up for adequate statistical power. As a result, very few interventions targeting CKD progression have been tested in randomized controlled trials. To overcome this problem, the National Kidney Foundation and Food and Drug Administration conducted a series of analyses to determine whether an end point of 30 or 40% decline in estimated glomerular filtration rate (eGFR) over 2-3 years can substitute for serum creatinine doubling in the composite end point. These analyses demonstrated that these alternate kidney end points were significantly associated with subsequent risks of ESKD and death. However, the association between, and consistency of treatment effects on eGFR decline and clinical end points were influenced by baseline eGFR, follow-up duration and acute hemodynamic effects. The investigators concluded that a 40% eGFR decline is broadly acceptable as a kidney end point across a wide baseline eGFR range and that a 30% eGFR decline may be acceptable in some situations. Although these alternate kidney end points could potentially allow investigators to conduct shorter duration clinical trials with smaller sample sizes thereby generating evidence to guide clinical decision-making in a timely manner, it is uncertain whether these end points will improve trial efficiency and feasibility. This review critically appraises the evidence, strengths and limitations pertaining to eGFR end points.