Number and frequency of albuminuria measurements in clinical trials in diabetic nephropathy

Rationale, design and baseline characteristics of the effect of canagliflozin in patients with type 2 diabetes and microalbuminuria in the Japanese population: The CANPIONE study

AIM

To evaluate the effect of canagliflozin, a sodium-glucose co-transporter-2 (SGLT2) inhibitor, on albuminuria and the decline of estimated glomerular filtration rate (eGFR) in participants with type 2 diabetes and microalbuminuria.

METHODS

The CANPIONE study is a multicentre, randomized, parallel-group and open-labelled study consisting of a unique 24-week preintervention period, during which the rate of eGFR decline before intervention is estimated, followed by a 52-week intervention and a 4-week washout period. Participants with a geometric mean urinary albumin-to-creatinine ratio (UACR) of 50 and higher and less than 300 mg/g in two consecutive first-morning voids at two different time points, and an eGFR of 45 ml/min/1.73m² or higher, are randomly assigned to receive canagliflozin 100 mg daily or to continue guideline-recommended treatment, except for SGLT2 inhibitors. The first primary outcome is the change in UACR, and the second primary outcome is the change in eGFR slope.

RESULTS

A total of 258 participants were screened and 98 were randomized at 21 sites in Japan from August 2018 to May 2021. The mean baseline age was 61.4 years and 25.8% were female. The mean HbA1c was 7.9%, mean eGFR was 74.1 ml/min/1.73m² and median UACR was 104.2 mg/g.

CONCLUSIONS

The CANPIONE study will determine whether the SGLT2 inhibitor canagliflozin can reduce albuminuria and slow eGFR decline in participants with type 2 diabetes and microalbuminuria.

Risk factors associated with albuminuria in Rwanda: results from a STEPS survey

BACKGROUND

Non-communicable diseases (NCDs) are a growing burden which affects every part of the world, including developing countries. Chronic kidney disease (CKD) has varied etiology which can result from or complicate other NCDs such as diabetes and cardiovascular diseases. The growing prevalence of NCDs coupled with the increasing age in most developing countries, has seen a marked increase of CKD in these settings. CKD has been described as "the most neglected NCD" and greatly affects the quality of life of patients. It also places a huge economic burden on societies. However, few epidemiological data exist, particularly in sub-Saharan Africa. Assessment of the prevalence of albuminuria as a marker of kidney damage and CKD progression and its main risk factors was thus needed in Rwanda.

METHODS

This study analyzed data collected during the first STEPwise approach to NCD risk factor Surveillance (STEPS) survey in Rwanda, conducted from 2012 to 2013, to assess the prevalence of albuminuria. A multistage cluster sampling allowed to select a representative sample of the general population. Furthermore, descriptive, as well as univariable analyses and multiple logistic regression were performed to respond to the research question.

RESULTS

This survey brought a representative sample of 6,998 participants, among which 4,384 (62.65%) were female. Median age was 33 years (interquartile range, IQR 26-44), and over three quarters (78.45%) lived in rural areas. The albuminuria prevalence was 105.9 per 1,000 population. Overall, semi-urban and urban residency were associated with lower odds of CKD (odds ratio, OR 0.36, CI 0.23-0.56, p<0.001 and OR 0.34, CI 0.23-0.50, p<0.001, respectively) than rural status. Being married or living with a partner had higher odds (OR 1.44 (CI 1.03-2.02, p=0.031) and OR 1.62 (CI 1.06-2.48, p=0.026), respectively) of CKD than being single. Odds of positive albuminuria were also greater among participants living with human immunodeficiency virus (HIV) (OR 1.64, CI 1.09- 2.47, p=0.018). Gender, age group, smoking status and vegetable consumption, body mass index (BMI) and hypertension were not associated with albuminuria.

CONCLUSION

The albuminuria prevalence was estimated at 105.9 per 1,000 in Rwanda. Rural residence, partnered status and HIV positivity were identified as main risk factors for albuminuria. Increased early screening of albuminuria to prevent CKD among high-risk groups, especially HIV patients, is therefore recommended.

Renal haemodynamic response to sodium-glucose cotransporter-2 inhibition does not depend on protein intake: An analysis of three randomized controlled trials

High protein intake may increase intraglomerular pressure through dilation of the afferent arteriole. Sodium-glucose cotransporter-2 (SGLT2) inhibitors may reduce intraglomerular pressure through activation of tubuloglomerular feedback. Given these opposing effects, we assessed whether the effect of dapagliflozin on glomerular filtration rate (GFR) and urinary albumin-to-creatinine ratio (UACR) was modified by estimated dietary protein intake using data from three separate randomized controlled trials (DELIGHT, IMPROVE and DIAMOND). The median protein intake was 58.4, 63.6 and 90.0 g/d, respectively. In the DELIGHT trial (n = 233), dapagliflozin compared to placebo caused an acute and reversible dip in GFR of 2.1 and 2.2 mL/min/1.73 m² , and reduced UACR by 20.5% and 28.4% in participants with high and low protein intake, respectively. Similarly, in IMPROVE (n = 30) and DIAMOND (n = 53), the effect of dapagliflozin on GFR and UACR was comparable in participants with high and low protein intake (all P for interaction > 0.40). This post hoc, exploratory analysis of three clinical trials suggests that dietary protein intake does not modify the individual response of clinical kidney variables to dapagliflozin.

The Effect of Dapagliflozin on Albuminuria in DECLARE-TIMI 58

OBJECTIVE

Sodium-glucose cotransporter 2 inhibitors (SGLT2i) improve albuminuria in patients with high cardiorenal risk. We report albuminuria change in the Dapagliflozin Effect on Cardiovascular Events (DECLARE-TIMI 58) cardiovascular outcome trial, which included populations with lower cardiorenal risk.

RESEARCH DESIGN AND METHODS

DECLARE-TIMI 58 randomized 17,160 patients with type 2 diabetes, creatinine clearance >60 mL/min, and either atherosclerotic cardiovascular disease (CVD; 40.6%) or risk-factors for CVD (59.4%) to dapagliflozin or placebo. Urinary albumin-to-creatinine ratio (UACR) was tested at baseline, 6 months, 12 months, and yearly thereafter. The change in UACR over time was measured as a continuous and categorical variable (≤15, >15 to <30, ≥30 to ≤300, and >300 mg/g) by treatment arm. The composite cardiorenal outcome was a ≥40% sustained decline in the estimated glomerular filtration rate (eGFR) to <60 mL/min/1.73 m², end-stage kidney disease, and cardiovascular or renal death; specific renal outcome included all except cardiovascular death.

RESULTS

Baseline UACR was available for 16,843 (98.15%) participants: 9,067 (53.83%) with ≤15 mg/g, 2,577 (15.30%) with >15 to <30 mg/g, 4,030 (23.93%) with 30-300 mg/g, and 1,169 (6.94%) with >300 mg/g. Measured as a continuous variable, UACR improved from baseline to 4.0 years with dapagliflozin, compared with placebo, across all UACR and eGFR categories (all P < 0.0001). Sustained confirmed ≥1 category improvement in UACR was more common in dapagliflozin versus placebo (hazard ratio 1.45 [95% CI 1.35-1.56], P < 0.0001). Cardiorenal outcome was reduced with dapagliflozin for subgroups of UACR ≥30 mg/g (P < 0.0125, P _interaction = 0.033), and the renal-specific outcome was reduced for all UACR subgroups (P < 0.05, P _interaction = 0.480).

CONCLUSIONS

In DECLARE-TIMI 58, dapagliflozin demonstrated a favorable effect on UACR and renal-specific outcome across baseline UACR categories, including patients with normal albumin excretion. The results suggest a role for SGLT2i also in the primary prevention of diabetic kidney disease.

Changes in Albuminuria Predict Cardiovascular and Renal Outcomes in Type 2 Diabetes: A Post Hoc Analysis of the LEADER Trial

OBJECTIVE

A post hoc analysis to investigate the association between 1-year changes in albuminuria and subsequent risk of cardiovascular and renal events.

RESEARCH DESIGN AND METHODS

LEADER was a randomized trial of liraglutide up to 1.8 mg/day versus placebo added to standard care for 3.5-5 years in 9,340 participants with type 2 diabetes and high cardiovascular risk. We calculated change in urinary albumin-to-creatinine ratio (UACR) from baseline to 1 year in participants with >30% reduction (n = 2,928), 30-0% reduction (n = 1,218), or any increase in UACR (n = 4,124), irrespective of treatment. Using Cox regression, risks of major adverse cardiovascular events (MACE) and a composite nephropathy outcome (from 1 year to end of trial in subgroups by baseline UACR [<30 mg/g, 30-300 mg/g, or ≥300 mg/g]) were assessed. The analysis was adjusted for treatment allocation alone as a fixed factor and for baseline variables associated with cardiovascular and renal outcomes.

RESULTS

For MACE, hazard ratios (HRs) for those with >30% and 30-0% UACR reduction were 0.82 (95% CI 0.71, 0.94; P = 0.006) and 0.99 (0.82, 1.19; P = 0.912), respectively, compared with any increase in UACR (reference). For the composite nephropathy outcome, respective HRs were 0.67 (0.49, 0.93; P = 0.02) and 0.97 (0.66, 1.43; P = 0.881). Results were independent of baseline UACR and consistent in both treatment groups. After adjustment, HRs were significant and consistent in >30% reduction subgroups with baseline micro- or macroalbuminuria.

CONCLUSIONS

A reduction in albuminuria during the 1st year was associated with fewer cardiovascular and renal outcomes, independent of treatment. Albuminuria monitoring remains an important part of diabetes care, with great unused potential.

Short-Term Changes in Albuminuria and Risk of Cardiovascular and Renal Outcomes in Type 2 Diabetes Mellitus: A Post Hoc Analysis of the EMPA-REG OUTCOME Trial

Background

Early reduction in albuminuria with an SGLT2 (sodium‐glucose cotransporter 2) inhibitor may be a positive indicator of long‐term cardiovascular and renal benefits. We assessed changes in albuminuria during the first 12 weeks of treatment and subsequent long‐term cardiovascular and renal risks associated with the SGLT2 inhibitor, empagliflozin, in the EMPA‐REG OUTCOME (Empagliflozin Cardiovascular Outcome Event Trial in Type 2 diabetes Mellitus Patients) trial.

Methods and Results

We calculated the percentage urinary albumin creatinine ratio (UACR) change from baseline to week 12 in 6820 participants who did not experience a cardiovascular outcome (including 3‐point major cardiovascular events and cardiovascular death or hospitalization for heart failure) or renal outcome (defined as 40% decline in estimated glomerular filtration rate from baseline, estimated glomerular filtration rate <15 mL/min per 1.73 m², need for continuous renal‐replacement therapy, or renal death) during the first 12 weeks. Multivariable Cox regression models were used to estimate the hazard ratio (HR) for each 30% reduction in UACR with outcomes. Empagliflozin reduced UACR by 18% (95% CI, 14–22) at week 12 compared with placebo, and increased the likelihood of a >30% reduction in UACR (odds ratio, 1.42; 95% CI, 1.27–1.58; P<0.001). During 3.0 years of follow‐up, 704 major cardiovascular events, 440 cardiovascular deaths/hospitalizations for heart failure, and 168 renal outcomes were observed. Each 30% decrease in UACR during the first 12 weeks was statistically significantly associated with a lower hazard for major cardiovascular events (HR, 0.96; 95% CI, 0.93–0.99; P=0.012), cardiovascular deaths/hospitalizations for heart failure (HR, 0.94; 95% CI, 0.91–0.98; P=0.003), and renal outcomes (HR, 0.83; 95% CI, 0.78–0.89; P<0.001).

Conclusions

Short‐term reduction in UACR was more common with empagliflozin and was statistically significantly associated with a decreased risk of long‐term cardiovascular and renal outcomes.

Registration

URL: https://www.clinicaltrials.gov. Unique identifier: NCT01131676.

Effect of Gastric Bypass vs Best Medical Treatment on Early-Stage Chronic Kidney Disease in Patients With Type 2 Diabetes and Obesity: A Randomized Clinical Trial

Importance

Early-stage chronic kidney disease (CKD) characterized by microalbuminuria is associated with future cardiovascular events, progression toward end-stage renal disease, and early mortality in patients with type 2 diabetes.

Objective

To compare the albuminuria-lowering effects of Roux-en-Y gastric bypass (RYGB) surgery vs best medical treatment in patients with early-stage CKD, type 2 diabetes, and obesity.

Design, Setting, and Participants

For this randomized clinical trial, patients with established type 2 diabetes and microalbuminuria were recruited from a single center from April 1, 2013, through March 31, 2016, with a 5-year follow-up, including prespecified intermediate analysis at 24-month follow-up.

Intervention

A total of 100 patients with type 2 diabetes, obesity (body mass indexes of 30 to 35 [calculated as weight in kilograms divided by height in meters squared]), and stage G1 to G3 and A2 to A3 CKD (urinary albumin-creatinine ratio [uACR] >30 mg/g and estimated glomerular filtration rate >30 mL/min) were randomized 1:1 to receive best medical treatment (n = 49) or RYGB (n = 51).

Main Outcomes and Measures

The primary outcome was remission of albuminuria (uACR <30 mg/g). Secondary outcomes were CKD remission rate, absolute change in uACR, metabolic control, other microvascular complications, quality of life, and safety.

Results

A total of 100 patients (mean [SD] age, 51.4 [7.6] years; 55 [55%] male) were randomized: 51 to RYGB and 49 to best medical care. Remission of albuminuria occurred in 55% of patients (95% CI, 39%-70%) after best medical treatment and 82% of patients (95% CI, 72%-93%) after RYGB (P = .006), resulting in CKD remission rates of 48% (95% CI, 32%-64%) after best medical treatment and 82% (95% CI, 72%-92%) after RYGB (P = .002). The geometric mean uACRs were 55% lower after RYGB (10.7 mg/g of creatinine) than after best medical treatment (23.6 mg/g of creatinine) (P < .001). No difference in the rate of serious adverse events was observed.

Conclusions and Relevance

After 24 months, RYGB was more effective than best medical treatment for achieving remission of albuminuria and stage G1 to G3 and A2 to A3 CKD in patients with type 2 diabetes and obesity.

Trial Registration

ClinicalTrials.gov Identifier: NCT01821508.

NGAL and SMAD1 gene expression in the early detection of diabetic nephropathy by liquid biopsy

INTRODUCTION

Diabetic nephropathy (DN) is a disease that progresses with the slow and progressive decline of the glomerular filtration rate (GFR); the installation of this pathology is silent and one of the major causes of death in patients with diabetes.

AIMS

To identify new molecular biomarkers for early identification of the onset of DN in patients with type II diabetes mellitus (DM2). We studied the expression profile of the genes; suppressor of mothers against decapentaplegic type 1 (SMAD1), neutrophil gelatinase-associated lipocalin (NGAL) and type IV collagen (COLIV1A) in peripheral blood and urine sediment samples.

METHODS

Ninety volunteers, 51 with DM2 and 39 healthy, were recruited from the Faculdade de Medicina do ABC outpatient clinic. We conducted an interview and collected anthropometric data, as well as blood and urine samples for biochemical evaluation and real-time PCR amplification of the genes of interest.

RESULTS

Gene expression data: peripheral blood NGAL (DM2 0.09758±0.1914 vs CTL 0.02293±0.04578), SMAD1 (blood: DM2 0.01102±0.04059* vs CTL 0.0001317±0.0003609; urine: DM2 0.7195±2.344* vs CTL 0.09812±0.4755), there was no significant expression of COLIV1A. These genes demonstrated good sensitivity and specificity in the receiving operating characteristic curve evaluation.

CONCLUSION

Our data suggest the potential use of NGAL and SMAD1 gene expression in peripheral blood and urine samples as early biomarkers of DN.

Change in albuminuria as a surrogate endpoint for progression of kidney disease: a meta-analysis of treatment effects in randomised clinical trials

BACKGROUND

Change in albuminuria has strong biological plausibility as a surrogate endpoint for progression of chronic kidney disease, but empirical evidence to support its validity is lacking. We aimed to determine the association between treatment effects on early changes in albuminuria and treatment effects on clinical endpoints and surrograte endpoints, to inform the use of albuminuria as a surrogate endpoint in future randomised controlled trials.

METHODS

In this meta-analysis, we searched PubMed for publications in English from Jan 1, 1946, to Dec 15, 2016, using search terms including "chronic kidney disease", "chronic renal insufficiency", "albuminuria", "proteinuria", and "randomized controlled trial"; key inclusion criteria were quantifiable measurements of albuminuria or proteinuria at baseline and within 12 months of follow-up and information on the incidence of end-stage kidney disease. We requested use of individual patient data from the authors of eligible studies. For all studies that the authors agreed to participate and that had sufficient data, we estimated treatment effects on 6-month change in albuminuria and the composite clinical endpoint of treated end-stage kidney disease, estimated glomerular filtration rate of less than 15 mL/min per 1·73 m², or doubling of serum creatinine. We used a Bayesian mixed-effects meta-regression analysis to relate the treatment effects on albuminuria to those on the clinical endpoint across studies and developed a prediction model for the treatment effect on the clinical endpoint on the basis of the treatment effect on albuminuria.

FINDINGS

We identified 41 eligible treatment comparisons from randomised trials (referred to as studies) that provided sufficient patient-level data on 29 979 participants (21 206 [71%] with diabetes). Over a median follow-up of 3·4 years (IQR 2·3-4·2), 3935 (13%) participants reached the composite clinical endpoint. Across all studies, with a meta-regression slope of 0·89 (95% Bayesian credible interval [BCI] 0·13-1·70), each 30% decrease in geometric mean albuminuria by the treatment relative to the control was associated with an average 27% lower hazard for the clinical endpoint (95% BCI 5-45%; median R² 0·47, 95% BCI 0·02-0·96). The association strengthened after restricting analyses to patients with baseline albuminuria of more than 30 mg/g (ie, 3·4 mg/mmol; R² 0·72, 0·05-0·99]). For future trials, the model predicts that treatments that decrease the geometric mean albuminuria to 0·7 (ie, 30% decrease in albuminuria) relative to the control will provide an average hazard ratio (HR) for the clinical endpoint of 0·68, and 95% of sufficiently large studies would have HRs between 0·47 and 0·95.

INTERPRETATION

Our results support a role for change in albuminuria as a surrogate endpoint for the progression of chronic kidney disease, particularly in patients with high baseline albuminuria; for patients with low baseline levels of albuminuria this association is less certain.

FUNDING

US National Kidney Foundation.

Biological Variability of Estimated GFR and Albuminuria in CKD

RATIONALE & OBJECTIVE

Determining whether a change in estimated glomerular filtration rate (eGFR) or albuminuria is clinically significant requires knowledge of short-term within-person variability of the measurements, which few studies have addressed in the setting of chronic kidney disease.

STUDY DESIGN

Cross-sectional study with multiple collections over less than 4 weeks.

SETTING & PARTICIPANTS

Clinically stable outpatients with chronic kidney disease (N=50; mean age, 56.8 years; median eGFR, 40mL/min/1.73m²; median urinary albumin-creatinine ratio (UACR), 173mg/g).

EXPOSURE

Repeat measurements from serially collected samples across 3 study visits.

OUTCOMES

Measurements of urine albumin concentration (UAC), UACR, and plasma creatinine, cystatin C, β₂-microglobulin (B2M), and beta trace protein (BTP).

ANALYTICAL APPROACH

We calculated within-person coefficients of variation (CV_w) values and corresponding reference change positive and negative (RCV_pos and RCV_neg) values using log-transformed measurements.

RESULTS

Median CV_w (RCV_pos; RCV_neg) values of filtration markers were 5.4% (+16%; -14%) for serum creatinine, 4.1% (+12%; -11%) for cystatin C, 7.4% (+23%; -18%) for BTP, and 5.6% (+17%; -14%) for B2M. Results for albuminuria were 33.2% (+145%; -59%) for first-morning UAC, 50.6% (+276%; -73%) for random spot UAC, 32.5% (+141%; -58%) for first-morning UACR, and 29.7% (124%; -55%) for random spot UACR. CV_w values for filtration markers were comparable across the range of baseline eGFRs. CV_w values for UAC and UACR were comparable across the range of baseline albuminuria values.

LIMITATIONS

Small sample size limits the ability to detect differences in variability across markers. Participants were recruited and followed up in a clinical and not research setting, so some preanalytical factors could not be controlled.

CONCLUSIONS

eGFR markers appear to have relatively low short-term within-person variability, whereas variability in albuminuria appears to be high, making it difficult to distinguish random variability from meaningful biologic changes.

Long-term intra-individual variability of albuminuria in type 2 diabetes mellitus: implications for categorization of albumin excretion rate

BACKGROUND

Diabetic kidney disease (DKD) is the leading cause of end-stage renal disease in the Western world. Early and accurate identification of DKD offers the best chance of slowing the progression of kidney disease. An important method for evaluating risk of progressive DKD is abnormal albumin excretion rate (AER). Due to the high variability in AER, most guidelines recommend the use of more than or equal to two out of three AER measurements within a 3- to 6-month period to categorise AER. There are recognised limitations of using AER as a marker of DKD because one quarter of patients with type 2 diabetes may develop kidney disease without an increase in albuminuria and spontaneous regression of albuminuria occurs frequently. Nevertheless, it is important to investigate the long-term intra-individual variability of AER in participants with type 2 diabetes.

METHODS

Consecutive AER measurements (median 19 per subject) were performed in 497 participants with type 2 diabetes from 1999 to 2012 (mean follow-up 7.9 ± 3 years). Baseline clinical characteristics were collected to determine associations with AER variability. Participants were categorised as having normo-, micro- or macroalbuminuria according to their initial three AER measurements. Participants were then categorised into four patterns of AER trajectories: persistent, intermittent, progressing and regressing. Coefficients of variation were used to measure intra-individual AER variability.

RESULTS

The median coefficient of variation of AER was 53.3%, 76.0% and 67.0% for subjects with normo-, micro- or macroalbuminuria at baseline. The coefficient of variation of AER was 37.7%, 66% and 94.8% for subjects with persistent, intermittent and progressing normoalbuminuria; 43%, 70.6%, 86.1% and 82.3% for subjects with persistent, intermittent, progressing and regressing microalbuminuria; and 55.2%, 67% and 82.4% for subjects with persistent, intermittent and regressing macroalbuminuria, respectively.

CONCLUSION

High long-term variability of AER suggests that two out of three AER measurements may not always be adequate for the optimal categorisation and prediction of AER.

Effect of Processing Delay and Storage Conditions on Urine Albumin-to-Creatinine Ratio

BACKGROUND AND OBJECTIVES

Because there is substantial biologic intraindividual variation in albumin excretion, randomized trials of albuminuria-reducing therapies may need multiple urine samples to estimate daily urinary albumin excretion. Mailing spot urine samples could offer a convenient and cost-effective method to collect multiple samples, but urine albumin-to-creatinine ratio stability in samples stored at ambient temperatures for several days is unknown.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Patients with kidney disease provided fresh urine samples in two tubes (with and without boric acid preservative). Reference aliquots from each participant were analyzed immediately, whereas remaining aliquots were subject to different handling/storage conditions before analysis, including delayed processing for up to 7 days at three different storage temperatures (4°C, 18°C, and 30°C), multiple freeze-thaw cycles, and long-term frozen storage at -80°C, -40°C, and -20°C. We calculated the mean percentage change in urine albumin-to-creatinine ratio for each condition, and we considered samples stable if the 95% confidence interval was within a ±5% threshold.

RESULTS

Ninety-three patients provided samples with detectable albuminuria in the reference aliquot. Median (interquartile range) urine albumin-to-creatinine ratio was 87 (20-499) mg/g. The inclusion of preservative had minimal effect on fresh urine albumin-to-creatinine ratio measurements but reduced the changes in albumin and creatinine in samples subject to processing delay and storage conditions. The urine albumin-to-creatinine ratio was stable for 7 days in samples containing preservative at 4°C and 18°C and 2 days when stored at 30°C. It was also stable in samples with preservative after three freeze-thaw cycles and in frozen storage for 6 months at -80°C or -40°C but not at -20°C.

CONCLUSIONS

Mailed urine samples collected with preservative and received within 7 days if ambient temperature is ≤18°C, or within 2 days if the temperature is higher but does not exceed 30°C, are suitable for the measurement of urine albumin-to-creatinine ratio in randomized trials. Preserved samples frozen to -40°C or -80°C for 6 months before analysis also seem suitable.

Determining the Optimal Protocol for Measuring an Albuminuria Class Transition in Clinical Trials in Diabetic Kidney Disease

Albuminuria class transition (normo- to micro- to macroalbuminuria) is used as an intermediate end point to assess renoprotective drug efficacy. However, definitions of such class transition vary between trials. To determine the most optimal protocol, we evaluated the approaches used in four clinical trials testing the effect of renin-angiotensin-aldosterone system intervention on albuminuria class transition in patients with diabetes: the BENEDICT, the DIRECT, the ALTITUDE, and the IRMA-2 Trial. The definition of albuminuria class transition used in each trial differed from the definitions used in the other trials by the number (one, two, or three) of consecutively collected urine samples at each study visit, the time interval between study visits, the requirement of an additional visit to confirm the class transition, and the requirement of a percentage increase in albuminuria from baseline in addition to the class transition. In Cox regression analysis, neither increasing the number of urine samples collected at a single study visit nor differences in the other variables used to define albuminuria class transition altered the average drug effect. However, the SEM of the treatment effect increased (decreased precision) with stricter end point definitions, resulting in a loss of statistical significance. In conclusion, the optimal albuminuria transition end point for use in drug intervention trials can be determined with a single urine collection for albuminuria assessment per study visit. A confirmation of the end point or a requirement of a minimal percentage change in albuminuria from baseline seems unnecessary.

Proteomic prediction and Renin angiotensin aldosterone system Inhibition prevention Of early diabetic nephRopathy in TYpe 2 diabetic patients with normoalbuminuria (PRIORITY): essential study design and rationale of a randomised clinical multicentre trial

INTRODUCTION

Diabetes mellitus affects 9% of the European population and accounts for 15% of healthcare expenditure, in particular, due to excess costs related to complications. Clinical trials aiming for earlier prevention of diabetic nephropathy by renin angiotensin system blocking treatment in normoalbumuric patients have given mixed results. This might reflect that the large fraction of normoalbuminuric patients are not at risk of progression, thereby reducing power in previous studies. A specific risk classifier based on urinary proteomics (chronic kidney disease (CKD)273) has been shown to identify normoalbuminuric diabetic patients who later progressed to overt kidney disease, and may hold the potential for selection of high-risk patients for early intervention. Combining the ability of CKD273 to identify patients at highest risk of progression with prescription of preventive aldosterone blockade only to this high-risk population will increase power. We aim to confirm performance of CKD273 in a prospective multicentre clinical trial and test the ability of spironolactone to delay progression of early diabetic nephropathy.

METHODS AND ANALYSIS

Investigator-initiated, prospective multicentre clinical trial, with randomised double-masked placebo-controlled intervention and a prospective observational study. We aim to include 3280 type 2 diabetic participants with normoalbuminuria. The CKD273 classifier will be assessed in all participants. Participants with high-risk pattern are randomised to treatment with spironolactone 25 mg once daily, or placebo, whereas, those with low-risk pattern will be observed without intervention other than standard of care. Treatment or observational period is 3 years.The primary endpoint is development of confirmed microalbuminuria in 2 of 3 first morning voids urine samples.

ETHICS AND DISSEMINATION

The study will be conducted under International Conference on Harmonisation - Good clinical practice (ICH-GCP) requirements, ethical principles of Declaration of Helsinki and national laws. This first new biomarker-directed intervention trial aiming at primary prevention of diabetic nephropathy may pave the way for personalised medicine approaches in treatment of diabetes complications.

TRIAL REGISTRATION NUMBER

NCT02040441; Pre-results.

Consecutive first-morning urine samples to measure change in the albumin-to-creatinine ratio: a pilot study of a home urine collection protocol

Background

Multiple first-morning urine samples are recommended for measuring the urine albumin-to-creatinine ratio (ACR); however, this can be challenging in community-based research.

Methods

The objectives of the study are to pilot-test a home urine collection protocol and examine how the average and variance of ACR varied with the number of urine collections and time to laboratory analysis. This is a prospective observational pilot study. This study was conducted in London, Ontario, Canada at the London Health Sciences Centre (2012–2013). The patients were adults with chronic kidney disease (mean estimated glomerular filtration rate, 36 mL/min/1.73 m²). Participants collected a first-morning 20-mL urine sample on three consecutive days. This process was repeated after 3 months. Samples were picked up by hospital courier and analyzed for ACR on the same day; additional aliquots were analyzed after a delay of 24–48 h (stored at 4 °C) and 3–9 months (stored at –80 °C). The geometric mean of the percentage change in ACR between baseline and 3 months was calculated and compared between single samples and the average of two vs. three consecutive samples.

Results

Of 31 patients enrolled, 26 (83.9 %) submitted all six urine samples. The geometric mean of ACR for three consecutive samples at baseline was 87, 83, and 80 mg/mmol, and the corresponding percentage increase from baseline to 3 months was 15 % (95 % confidence interval (CI), −9 to 46 %), 33 % (95 % CI, 10 to 59 %), and 22 % (95 % CI, −6 to 57 %). Compared with single urine collections at baseline and follow-up, averaging ACR values from two consecutive first-morning urine samples improved the sample variance and reduced the required sample size to detect a given treatment effect by approximately 30 %. No further gain in statistical efficiency was achieved with three urine samples. Results were similar when the laboratory analysis was delayed by 24–48 h, but a delay of 3–9 months resulted in systematic overestimation of the ACR. Our study’s generalizability is limited by its small sample size and reliance on a clinic-based population from a single urban center.

Conclusions

We successfully used a home urine collection protocol to obtain multiple first-morning urine samples in patients with chronic kidney disease. Statistical efficiency was improved by averaging ACR values from two consecutive first-morning urine samples at baseline and follow-up.

Individual long-term albuminuria exposure during angiotensin receptor blocker therapy is the optimal predictor for renal outcome

BACKGROUND

Albuminuria reduction due to angiotensin receptor blockers (ARBs) predicts subsequent renoprotection. Relating the initial albuminuria reduction to subsequent renoprotection assumes that the initial ARB-induced albuminuria reduction remains stable during follow-up. The aim of this study was to assess individual albuminuria fluctuations after the initial ARB response and to determine whether taking individual albuminuria fluctuations into account improves renal outcome prediction.

METHODS

Patients with diabetes and nephropathy treated with losartan or irbesartan in the RENAAL and IDNT trials were included. Patients with >30% reduction in albuminuria 3 months after ARB initiation were stratified by the subsequent change in albuminuria until Month 12 in enhanced responders (>50% albuminuria reduction), sustained responders (between 20 and 50% reduction), and response escapers (<20% reduction). Predictive performance of the individual albuminuria exposure until Month 3 was compared with the exposure over the first 12 months using receiver operating characteristics (ROC) curves.

RESULTS

Following ARB initiation, 388 (36.3%) patients showed an >30% reduction in albuminuria. Among these patients, the albuminuria level further decreased in 174 (44.8%), remained stable in 123 (31.7%), and increased in 91 (23.5%) patients. Similar albuminuria fluctuations were observed in patients with <30% albuminuria reduction. Renal risk prediction improved when using the albuminuria exposure during the first 12 months versus the initial Month 3 change [ROC difference: 0.78 (95% CI 0.75-0.82) versus 0.68 (0.64-0.72); P < 0.0001].

CONCLUSIONS

Following the initial response to ARBs, a large within-patient albuminuria variability is observed. Hence, incorporating multiple albuminuria measurements over time in risk algorithms may be more appropriate to monitor treatment effects and quantify renal risk.