Proteinuria as a risk factor for cardiovascular disease and mortality in older people: a prospective study

Urinary Plasminogen as a Marker of Disease Progression in Human Glomerular Disease

RATIONALE & OBJECTIVE

Glomerular disorders have a highly variable clinical course, and biomarkers that reflect the molecular mechanisms underlying their progression are needed. Based on our previous work identifying plasminogen as a direct cause of podocyte injury, we designed this study to test the association between urine plasmin(ogen) (ie, plasmin and its precursor plasminogen) and end-stage kidney disease (ESKD).

STUDY DESIGN

Multicenter cohort study.

SETTING & PARTICIPANTS

1,010 patients enrolled in the CureGN Cohort with biopsy-proven glomerular disease (focal segmental glomerulosclerosis, membranous nephropathy, and immunoglobulin A nephropathy).

PREDICTORS

The main predictor was urine plasmin(ogen) at baseline. Levels were measured by an electrochemiluminescent immunoassay developed de novo. Traditional clinical and analytical characteristics were used for adjustment. The ratio of urine plasmin(ogen)/expected plasmin(ogen) was evaluated as a predictor in a separate model.

OUTCOME

Progression to ESKD.

ANALYTICAL APPROACH

Cox regression was used to examine the association between urinary plasmin(ogen) and time to ESKD. Urinary markers were log2 transformed to approximate normal distribution and normalized to urinary creatinine (Log2uPlasminogen/cr, Log2 urinary protein/cr [UPCR]). Expected plasmin(ogen) was calculated by multiple linear regression.

RESULTS

Adjusted Log2uPlasminogen/cr was significantly associated with ESKD (HR per doubling Log2 uPlasminogen/cr 1.31 [95% CI, 1.22-1.40], P<0.001). Comparison of the predictive performance of the models including Log2 uPlasminogen/cr, Log2 UPCR, or both markers showed the plasmin(ogen) model superiority. The ratio of measured/expected urine plasmin(ogen) was independently associated with ESKD: HR, 0.41 (95% CI, 0.22-0.77) if ratio<0.8 and HR 2.42 (95% CI, 1.54-3.78) if ratio>1.1 (compared with ratio between 0.8 and 1.1).

LIMITATIONS

Single plasmin(ogen) determination does not allow for the study of changes over time. The use of a cohort of mostly white patients and the restriction to patients with 3 glomerular disorders limits the external validity of our analysis.

CONCLUSIONS

Urinary plasmin(ogen) and the ratio of measured/expected plasmin(ogen) are independently associated with ESKD in a cohort of patients with glomerular disease. Taken together with our previous experimental findings, urinary plasmin(ogen) could be a useful biomarker in prognostic decision making and a target for the development of novel therapies in patients with proteinuria and glomerular disease.

PLAIN-LANGUAGE SUMMARY

Glomerular diseases are an important cause of morbidity and mortality in patients of all ages. Knowing the individual risk of progression to dialysis or transplantation would help to plan the follow-up and treatment of these patients. Our work studies the usefulness of urinary plasminogen as a marker of progression in this context, since previous studies indicate that plasminogen may be involved in the mechanisms responsible for the progression of these disorders. Our work in a sample of 1,010 patients with glomerular disease demonstrates that urinary plasminogen (as well as the ratio of measured to expected plasminogen) is associated with the risk of progression to end-stage kidney disease. Urine plasminogen exhibited good performance and, if further validated, could enable risk stratification for timely interventions in patients with proteinuria and glomerular disease.

Association between Proteinuria Status and Risk of Hypertension: A Nationwide Population-Based Cohort Study

Proteinuria is associated with cardiovascular disease. However, the relationship between changes in proteinuria status and hypertension remains unclear. This study aimed to explore the association between changes in proteinuria status and the risk of developing hypertension with the data from the Korean National Health Insurance Database. We included participants without prior hypertension history who underwent their first health examination in 2003-2004 and a second examination in 2005-2006. Based on their proteinuria status during these two examinations, participants were classified into four groups: the proteinuria-free, proteinuria-resolved, proteinuria-developed, and chronic proteinuria groups. The study outcome was the incidence of hypertension. The study included 935,723 participants followed for a median of 14.2 years (mean age: 40.96 ± 11.01, 62.5% male participants). During this period, 346,686 (37.1%) cases of hypertension were reported. The chronic proteinuria group had the highest hypertension risk, followed by the proteinuria-developed, proteinuria-resolved, and proteinuria-free groups (p < 0.001). Those who recovered from proteinuria had a lower risk of developing hypertension than those with chronic proteinuria (hazard ratio: 0.58; 95% confidence interval: 0.53-0.63, p < 0.001). In contrast, individuals who developed proteinuria had a higher risk of hypertension than proteinuria-free individuals (hazard ratio: 1.31; 95% confidence interval: 1.26-1.35, p < 0.001). Our findings suggest a significant association between proteinuria status changes and hypertension. Effective management of proteinuria may potentially decrease the risk of developing hypertension.

Prognostic value of proteinuria monitoring in anti-neutrophil cytoplasmic antibody-associated vasculitis

OBJECTIVE

To determine the prognostic significance of proteinuria monitoring in patients with anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV).

METHODS

We retrospectively analyzed the data of kidney biopsy-confirmed patients with AAV. Proteinuria was evaluated by a urine dipstick test. Poor renal outcome was defined as stage 4/5 chronic kidney disease (CKD) (estimated glomerular filtration rate < 30 mL/min/1.73 m2).

RESULTS

We enrolled 77 patients with a median follow-up duration of 36 months (interquartile range, 18-79) in this study. Excluding 8 patients on dialysis at 6 months, 59/69 (85.5%) achieved remission after induction therapy. Patients were then divided into two groups according to the presence of proteinuria at 6 months after induction therapy (n = 29 with proteinuria, 40 without proteinuria). There was no significant difference in the rate of relapse or death according to the presence of proteinuria (p = 0.304 relapse, 0.401 death). In contrast, patients with proteinuria had significantly lower kidney function than those without proteinuria (41 vs. 53.5 mL/min/1.73 m2, p = 0.003). Multivariate analysis revealed that eGFR values at 6 months (hazard ratio [HR] 0.925; 95% CI 0.875-0.978, p = 0.006) and proteinuria at 6 months (HR 4.613; 95% CI 1.230-17.298, p = 0.023) were significantly associated with stage 4/5 CKD.

CONCLUSION

The presence of proteinuria at 6 months after induction therapy and low renal function was significantly associated with a higher risk of stage 4/5 CKD in patients with AAV. Monitoring for proteinuria after induction therapy may help predict poor renal outcomes in patients with AAV.

Association of proteinuria and risk of incident atrial fibrillation in the general population: A prospective study of Kailuan study participants

BACKGROUND

Proteinuria is a well-known cardiovascular risk factor, but whether it independently increases the risk for atrial fibrillation (AF) in Chinese population is unknown. To address this deficiency, herein, we investigated the association between proteinuria detected using urine dipstick test and the risk of AF.

METHODS

This was a prospective cohort study of Kailuan study participants who underwent the 2006-2007 and 2010-2011 health checkups and was free from AF. Participants were classified into four groups based on the level of proteinuria: [-, trace (±), 1+, ≥2+]. The outcome was incident AF as confirmed by 12-lead electrocardiography.

RESULTS

During a median of 11.90 years of follow-up, we documented 514 incident AF cases among 60,599 participants. Proteinuria was found in 6302 (10.40%) participants. Relative to participants without proteinuria at the baseline, those with proteinuria (≥2+) had an 83.9% higher risk (95% confidence interval [CI], 1.073-3.154, p = .0267) of developing AF, after adjusted for confounding variables. The result was consistent in the sensitivity analysis. Compared to consistently negative proteinuria, the risk of AF significantly increased in the aggravated proteinuria group (hazard ratio [HR] 1.552, 95% CI 1.140-2.114) and the persistent proteinuria group (HR 2.485, 95% CI 1.414-4.366). Among participants with resolved proteinuria (from positive to negative), the risk of incident AF was not significantly increased compared to those with persistently negative proteinuria (HR 1.300, 95% CI 0.743-2.276).

CONCLUSIONS

Proteinuria could be a modifiable risk factor for predicting AF development. Knowing the presence of proteinuria may improve risk stratification for decision-making about AF prevention.

Body Mass Index and the Risk of Persistent Proteinuria in Middle-Aged Men: The Kansai Healthcare Study

INTRODUCTION

Proteinuria is a risk factor for end-stage renal failure. However, it is not known whether body mass index (BMI) is prospectively associated with the risk of future developing proteinuria, taking into account transient proteinuria.

METHODS

We enrolled 9,320 nondiabetic Japanese middle-aged men who had no proteinuria, an estimated glomerular filtration rate ≥60 mL/min/1.73 m2, no history of cancer, and no use of antihypertensive medications at baseline. "Any proteinuria" was defined as proteinuria detected for the first time during the follow-up period regardless of its frequency. "Persistent proteinuria" was defined as proteinuria that was detected at least twice consecutively at annual examinations and did not return to negative until the end of the follow-up.

RESULTS

During the 11-year follow-up period, 1,972 cases of any proteinuria and 151 cases of persistent proteinuria were confirmed. Both lower and higher BMI were associated with the risk of any proteinuria. As for persistent proteinuria, in those with a BMI ≥20 kg/m2, higher BMI was associated with a higher risk of future persistent proteinuria. The association between BMI and the risk of persistent proteinuria was stronger than that between BMI and any proteinuria. In multiple-adjusted model, hazard ratios of persistent proteinuria for BMI <18.0, 18.0-19.9, 20.0-21.9, 22.0-23.9, 24.0-25.9, 26.0-27.9, and ≥28.0 kg/m2 were 1.52 (95% confidence interval 0.51-4.49), 1.07 (0.49-2.29), 1.00 (reference), 1.14 (0.64-2.01), 1.89 (1.09-3.27), 2.12 (1.15-3.93), and 3.85 (2.03-7.30), respectively.

DISCUSSION/CONCLUSION

In those with a BMI ≥20 kg/m2, higher BMI was associated with a higher risk of future persistent proteinuria and any proteinuria. This relationship was stronger for persistent proteinuria than for any proteinuria.

The relationship between urinary albumin to creatinine ratio and all-cause mortality in the elderly population in the Chinese community: a 10-year follow-up study

BACKGROUND

In patients with diabetes and hypertension, proteinuria is independently associated with all-cause death. However, in the general population, urinary albumin to creatinine ratio (UACR) is less used to predict all-cause mortality. When the urinary albumin to creatinine ratio is within the normal range (UACR< 30 mg/g), the clinical relevance of an increased urinary albumin excretion rate is still debated. We studied the relationship between UACR and all-cause mortality in community populations, and compared UACR groups within the normal range.

METHODS

The participants were the inhabitants from the Wanshoulu community in Beijing, China. The average age is 71.48 years, and the proportion of women is 60.1%. A total of 2148 people completed random urine samples to determine the urinary albumin to creatinine ratio (UACR). The subjects were divided into three groups according to UACR: Group 1 (UACR< 10 mg/g), Group 2 (10 mg/g < UACR< 30 mg/g), Group 3 (UACR> 30 mg/g). We used Kaplan-Meier survival analysis and Cox regression model to verify the relationship between UACR and all-cause mortality.

RESULTS

At an average follow-up of 9.87 years (718,407.3 years), the total mortality rate were 183.4/1000. In the Cox proportional hazards model, after adjusting for possible confounders, those with normal high-value UACR (group 2) showed a higher all-cause mortality than those with normal low-value UACR (group 1) [hazard ratio (HR) 1.289, 95% confidence interval (CI) 1.002 ~ 1.659 for all-cause mortality]. Those with proteinuria (group 3) showed a higher all-cause mortality than those with normal low-value UACR (group 1) [hazard ratio (HR) 1.394, 95% confidence interval (CI) 1.020 ~ 1.905 for all-cause mortality].

CONCLUSION

Urinary albumin to creatinine ratio is an important risk factor for all-cause death in community population. Even if it is within the normal range (UACR< 30 mg/g), it occurs in people with high normal value (10 mg/g < UACR< 30 mg/g), the risk of all-cause death will also increase.

Urine Protein Levels Predict Future Development of Cerebral Infarction in Koreans

PURPOSE

Proteinuria is a clinical sign of adverse cardiovascular outcomes, including stroke. We aimed to assess the relationship between proteinuria and the occurrence of cerebral infarction.

MATERIALS AND METHODS

In total, 208854 Koreans who participated in the 2009 medical examination were followed up until 2013 using the database of the National Health Insurance Service. The results of urine dipstick tests were utilized to assess proteinuria as absent, 1+, 2+, or ≥3+. The International Classification of Diseases code 163 was used to document cerebral infarction.

RESULTS

Between 2009 and 2013, 2383 cases (1.14%) of cerebral infarction occurred during 912772.9 person-years of follow-up. Hazard ratios for incident cerebral infarction increased with inceasing amounts of urine protein from 1.53 (1.23-1.90) in group 2 (1+), 1.67 (1.22-2.28) in group 3 (2+), and 2.66 (1.79-3.96) in group 4 (≥3+), compared to the reference group with little to no detectable urine protein (p<0.001, respectively).

CONCLUSION

An increase in urine protein levels was significantly related to the risk of developing cerebral infarction. Our results suggest that proteinuria might be a potential risk factor for cerebral infarction and that urine dipstick test analysis may be clinically useful for predicting stroke.

Proteinuria is independently associated with carotid atherosclerosis: a multicentric study

BACKGROUND AND AIMS

Atherosclerosis is a vital cause of cardiovascular diseases. The correlation between proteinuria and atherosclerosis, however, has not been confirmed. This study aimed to assess whether there is a relationship between proteinuria and atherosclerosis.

METHODS

From January 2016 to September 2020, 13,545 asymptomatic subjects from four centres in southern China underwent dipstick proteinuria testing and carotid atherosclerosis examination. Data on demography and past medical history were collected, and laboratory examinations were performed. The samples consisted of 7405 subjects (4875 males and 2530 females), excluding subjects failing to reach predefined standards and containing enough information. A multivariate logistic regression model was used to adjust the influence of traditional risk factors for atherosclerosis on the results.

RESULTS

Compared with proteinuria-negative subjects, proteinuria-positive subjects had a higher prevalence rate of carotid atherosclerosis. The differences were statistically significant (22.6% vs. 26.7%, χ² = 10.03, p = 0.002). After adjusting for common risk factors for atherosclerosis, age, sex, BMI, blood lipids, blood pressure, renal function, hypertensive disease, diabetes mellitus and hyperlipidaemia, proteinuria was an independent risk factor for atherosclerosis (OR = 1.191, 95% CI 1.015-1.398, p = 0.033). The Hosmer-Lemeshow test was used to test the risk prediction model of atherosclerosis, and the results showed that the model has high goodness of fit and strong independent variable prediction ability.

CONCLUSIONS

Proteinuria is independently related to carotid atherosclerosis. With the increase in proteinuria level, the risk of carotid atherosclerotic plaque increases. For patients with positive proteinuria, further examination of atherosclerosis should not be ignored.

Association between renal function and cardiovascular mortality: a retrospective cohort study of elderly from health check-up

OBJECTIVES

This study aimed to investigate the relationship between cardiovascular mortality in elderly Asians and decline in renal function.

DESIGN

A retrospective cohort study.

SETTING

Community-based health examination database from Taipei city.

PARTICIPANTS

At the beginning, the database included 315 045 health check-up visits of 97 803 elderly persons aged ≥65 years old from 2005 to 2012. After excluding missing values and outliers, there were 64 732 elderly persons with at least two visits retained for further analyses.

PRIMARY OUTCOME MEASURES

Kidney function indicators include estimated glomerular filtration rate (eGFR) and urine protein, and rapid decline in eGFR was defined as slope ≤ -5 mL/min/1.73 m² per year. The endpoint outcome was defined as the cardiovascular deaths registered in the death registry encoded by the International Classification of Diseases. We applied a Cox proportional hazards model to analyse the association between renal function and cardiovascular mortality.

RESULTS

In this study, we found 1264 elderly persons died from cardiovascular diseases, for whom the data included 4055 previous health check-up visits. We observed significant and independent associations of eGFR <60 mL/min/1.73 m² (HR (95% CI) of 60>eGFR≥45 and eGFR<45 in males: 2.85 (1.33 to 6.09) and 3.98 (1.84 to 8.61); in females: 3.66 (1.32 to 10.15) and 6.77 (2.41 to 18.99)), positive proteinuria (HR (95% CI) of +/-, +,++ and +++, ++++ in males: 1.51 (1.29 to 1.78) and 2.31 (1.51 to 3.53); in females: 1.93 (1.54 to 2.42) and 4.23 (2.34 to 7.65)) and rapid decline in eGFR (HR (95% CI) in males: 3.24 (2.73 to 3.85); in females: 2.83 (2.20 to 3.64) with higher risk of cardiovascular mortality. The joint effect of increased concentration of urine protein and reduced eGFR was associated with a higher risk of cardiovascular mortality.

CONCLUSIONS

Renal function and rapid decline in renal function are independent risk factors for cardiovascular mortality in the elderly.

Trace proteinuria as a risk factor for cancer death in a general population

Growing evidence has demonstrated an association between nondialysis chronic kidney disease and cancer incidence, although the association between trace proteinuria and cancer death remains unclear. The aim of this study was to investigate the association between trace proteinuria and cancer death in a community-based population in Japan. This was a prospective cohort study of 377,202 adults who participated in the Japanese Specific Health Check and Guidance System from 2008 to 2011. Exposure was dipstick proteinuria categorized as − (negative), ± (trace), 1 + (mild), or ≥ 2 + (moderate to heavy). Outcome was cancer death based on information from the national database of death certificates. Adjusted Cox hazard regression model was used to evaluate the associations between trace proteinuria and cancer death. During median follow-up of 3.7 years, 3056 cancer deaths occurred, corresponding to overall cancer death rate of 21.7/10,000 person-years. In the fully adjusted model, risk of cancer death increased significantly in each successive category of proteinuria: hazard ratio (HR) (95% confidence interval [95% CI]) for risk of cancer death was 1.16 (1.03–1.31), 1.47 (1.27–1.70), and 1.61 (1.33–1.96) for trace, mild, and moderate to heavy proteinuria, respectively. Sensitivity analyses revealed a similar association between trace proteinuria and cancer death, and participants with trace proteinuria had greater risk of mortality from hematological cancers (HR: 1.59 [95% CI: 1.09–2.31]). Both mild to heavy and trace proteinuria were significantly associated with risk of mortality from cancer in a general population.

Urine albumin dipstick independently predicts cardiovascular and renal outcomes among rural Thai population: a 14-year retrospective cohort study

Background

Albuminuria is an established risk marker for both cardiovascular and renal outcomes. In this study, we expected to use portable and inexpensive test strips to detect urine albumin level for risk stratification in cardiovascular and renal outcomes among rural Thai community.

Objective

To evaluate the relationship between urine albumin dipstick and cardiovascular and renal complications in rural Thai population.

Methods

We conducted a retrospective study in 635 rural Thai adults who tested urine albuminuria by using commercial urine albumin dipstick and the Micral-albumin test II strips at baseline. The subjects were divided into normoalbuminuria (albumin < 20 mg/L), microalbuminuria (albumin 20–200 mg/L), or macroalbuminuria (Urine dipstick at least 1+ or albumin > 200 mg/L). We collected data on the incidences of primary composite outcomes including cardiovascular or renal morbidity and mortality. Incident density and cox regression were analyzed to evaluate the association between albuminuria status and primary composite outcome.

Results

During an average 14-year follow-up, 102 primary composite events occurred including 59 (13.1%), 32 (20.6%) and 11 (39.3%) among 452, 155, and 28 subjects with normoalbuminuria, microalbuminuria, and macroalbuminuria, respectively. Incident densities of primary composite outcome were elevated continually according to the degree of albuminuria (9.36, 17.11 and 38.12 per 1000 person-years). Compared with the subjects without albuminuria, subjects with microalbuminuria and macroalbuminuria at baseline had higher risk for primary composite outcome in univariate model. After multivariate analysis was performed, the effect of macroalbuminuria was only persisted with 3.13-fold risk (adjusted HR 3.13; 95% CI 1.40–6.96, P= 0.005).

Conclusion

Albuminuria from semi-quantitative methods is an important factor predicting cardiovascular and renal risk among subjects in Thai rural population. Our findings support to also incorporating urine albumin dipstick into assessments of cardiovascular risk in the general population.

Plasminogenuria is associated with podocyte injury, edema, and kidney dysfunction in incident glomerular disease

Urinary plasminogen/plasmin, or plasmin (ogen) uria, has been demonstrated in proteinuric patients and exposure of cultured podocytes to plasminogen results in injury via oxidative stress pathways. A causative role for plasmin (ogen) as a "second hit" in kidney disease progression has yet to have been demonstrated in vivo. Additionally, association between plasmin (ogen) uria and kidney function in glomerular diseases remains unclear. We performed comparative studies in a puromycin aminonucleoside (PAN) nephropathy rat model treated with amiloride, an inhibitor of plasminogen activation, and measured changes in plasmin (ogen) uria. In a glomerular disease biorepository cohort (n = 128), we measured time-of-biopsy albuminuria, proteinuria, and plasmin (ogen) uria for correlations with kidney outcomes. In cultured human podocytes, plasminogen treatment was associated with decreased focal adhesion marker expression with rescue by amiloride. Increased glomerular plasmin (ogen) was found in PAN rats and focal segmental glomerulosclerosis (FSGS) patients. PAN nephropathy was associated with increases in plasmin (ogen) uria and proteinuria. Amiloride was protective against PAN-induced glomerular injury, reducing CD36 scavenger receptor expression and oxidative stress. In patients, we found associations between plasmin (ogen) uria and edema status as well as eGFR. Our study demonstrates a role for plasmin (ogen)-induced podocyte injury in the PAN nephropathy model, with amiloride having podocyte-protective properties. In one of the largest glomerular disease cohorts to study plasminogen, we validated previous findings while suggesting a potentially novel relationship between plasmin (ogen) uria and estimated glomerular filtration rate (eGFR). Together, these findings suggest a role for plasmin (ogen) in mediating glomerular injury and as a viable targetable biomarker for podocyte-sparing treatments.

Association of proteinuria with incident atrial fibrillation in the general Japanese population

BACKGROUND

Although proteinuria has been associated with incident atrial fibrillation (AF) in Western countries, the association has not been investigated in the general Japanese population.

METHODS

Participants aged ≥40 years who underwent the Japanese specific health check-up in Kanazawa City in 2013 and who completed a urine dipstick test were included in this study. Exposure was considered as presence or absence of proteinuria (≥1+). The outcome was incident AF confirmed by 12-lead electrocardiography. The Cox proportional hazard model was used to compute hazard ratio (HR) of proteinuria (≥1+) for incident AF after adjustment for traditional risk factors. We also completed stratified analyses by baseline characteristics.

RESULTS

A total of 37,910 participants aged ≥40 years were included (mean age: 72.3 years, male sex: 37%). Proteinuria ≥1+ was observed in 2.765 (7.3%) participants. During a median follow-up period of 5 years, 708 incident AF cases were observed. Proteinuria ≥1+ was associated with incident AF (HR, 1.47: 95% confidence interval, 1.18-1.84) after covariate adjustment. Stratified analysis demonstrated that the association of proteinuria with AF was stronger in participants <75 years [HR 1.89 (95% CI 1.32-2.70)] compared with those ≥75 years [HR 1.27 (95% CI 0.95-1.69)] (interaction p-value=0.02).

CONCLUSIONS

Proteinuria was significantly associated with incident AF in the general Japanese population. The evaluation of proteinuria using urine dipstick test may be useful in the evaluation of incident AF, especially in younger general population.

Development and validation of hybrid Brillouin-Raman spectroscopy for non-contact assessment of mechano-chemical properties of urine proteins as biomarkers of kidney diseases

BACKGROUND

Proteinuria is a major marker of chronic kidney disease (CKD) progression and the predictor of cardiovascular mortality. The rapid development of renal failure is expected in those patients who have higher level of proteinuria however, some patients may have slow decline of renal function despite lower level of urinary protein excretion. The different mechanical (visco-elastic) and chemical properties, as well as the proteome profiles of urinary proteins might explain their tubular toxicity mechanism. Brillouin light scattering (BLS) and surface enhanced Raman scattering (SERS) spectroscopies are non-contact, laser optical-based techniques providing visco-elastic and chemical property information of probed human biofluids. We proposed to study and compare these properties of urinary proteins using BLS and SERS spectroscopies in nephrotic patient and validate hybrid BLS-SERS spectroscopy in diagnostic of urinary proteins as well as their profiling. The project ultimately aims for the development of an optical spectroscopic sensor for rapid, non-contact monitoring of urine samples from patients in clinical settings.

METHODS

BLS and SERS spectroscopies will be used for non-contact assessment of urinary proteins in proteinuric patients and healthy subjects and will be cross-validated by Liquid Chromatography-Mass Spectrometry (LC-MS). Participants will be followed-up during the 1 year and all adverse events such as exacerbation of proteinuria, progression of CKD, complications of nephrotic syndrome, disease relapse rate and inefficacy of treatment regimen will be registered referencing incident dates. Associations between urinary protein profiles (obtained from BLS and SERS as well as LC-MS) and adverse outcomes will be evaluated to identify most unfavored protein profiles.

DISCUSSION

This prospective study is focused on the development of non-contact hybrid BLS - SERS sensing tool and its clinical deployment for diagnosis and prognosis of proteinuria. We will identify the most important types of urine proteins based on their visco-elasticity, amino-acid profile and molecular weight responsible for the most severe cases of proteinuria and progressive renal function decline. We will aim for the developed hybrid BLS - SERS sensor, as a new diagnostic & prognostic tool, to be transferred to other biomedical applications.

TRIAL REGISTRATION

The trial has been approved by ClinicalTrials.gov (Trial registration ID NCT04311684). The date of registration was March 17, 2020.

Effect of angiotensin receptor blockers on blood pressure and renal function in patients with concomitant hypertension and chronic kidney disease: a systematic review and meta-analysis

Objective: Angiotensin receptor blockers (ARB) are among the recommended first-line treatment options in patients with hypertension and chronic kidney disease (CKD). This meta-analysis evaluated the effect of ARB on blood pressure (BP) and renal function in patients with concomitant hypertension and CKD with or without diabetes.Methods: Literature search was performed in PubMed/MEDLINE, EMBASE and BIOSIS to identify parallel-group, randomized controlled trials (≥8 weeks) reporting the effects of ARB on office systolic/diastolic BP (SBP/DBP), estimated glomerular filtration rate (eGFR), serum creatinine (SCr), creatinine clearance (CrCl) or proteinuria in adults with hypertension and CKD. Mean difference (MD, generic inverse variance) with 95% confidence intervals (CIs) was used to report an outcome.Results: Among the 24 studies identified, 19 evaluated ARB as monotherapy, 4 evaluated ARB as combination therapy and one evaluated ARB both as monotherapy and combination therapy. Median (range) duration of the studies was 12 (1.84-54.0) months. ARB monotherapy significantly (p < 0.01) reduced BP (treatment ≥1 year: SBP [MD: -14.84 mmHg; 95% CI: -17.82 to -11.85]/DBP [-10.27 mmHg; -12.26 to -8.27]) and proteinuria (≥1 year [-0.90 g/L; -1.22 to -0.59]). Results were consistent for combination therapy. In these studies, non-significant changes were observed for eGFR, CrCl and SCr. The impact of SBP changes on eGFR was not significant; however, studies were of a relatively short duration.Conclusion: ARB had a favorable impact on BP and renal parameters such as proteinuria with monotherapy as well as with combination therapy, highlighting their potential benefits in patients with hypertension and CKD. During the short follow-up of these studies, no significant change in eGFR was observed.

Effects of Brazilian green propolis on proteinuria and renal function in patients with chronic kidney disease: a randomized, double-blind, placebo-controlled trial

Background

Chronic kidney disease (CKD) is a public health problem worldwide, and proteinuria is a well-established marker of disease progression in CKD patients. Propolis, a natural resin produced by bees from plant materials, has anti-inflammatory, immunomodulatory, and anti-oxidant properties, as well as having been shown to have an antiproteinuric effect in experimental CKD. The aim of this study was to evaluate the impact of Brazilian green propolis extract on proteinuria reduction and the changes in the estimated glomerular filtration rate (eGFR).

Methods

This was a randomized, double-blind, placebo-controlled study including patients with CKD caused by diabetes or of another etiology, 18–90 years of age, with an eGFR of 25–70 ml/min per 1.73 m² and proteinuria (urinary protein excretion > 300 mg/day) or micro- or macro-albuminuria (urinary albumin-to-creatinine ratio > 30 mg/g or > 300 mg/g, respectively). We screened 148 patients and selected 32, randomly assigning them to receive 12 months of Brazilian green propolis extract at a dose of 500 mg/day (n = 18) or 12 months of a placebo (n = 14).

Results

At the end of treatment, proteinuria was significantly lower in the propolis group than in the placebo group—695 mg/24 h (95% CI, 483 to 999) vs. 1403 mg/24 h (95% CI, 1031 to 1909); P = 0.004—independent of variations in eGFR and blood pressure, which did not differ between the groups during follow-up. Urinary monocyte chemoattractant protein-1 was also significantly lower in the propolis group than in the placebo group—58 pg/mg creatinine (95% CI, 36 to 95) vs. 98 pg/mg creatinine (95% CI, 62 to 155); P = 0.038.

Conclusions

Brazilian green propolis extract was found to be safe and well tolerated, as well as to reduce proteinuria significantly in patients with diabetic and non-diabetic CKD.

Trial Registration.

(ClinicalTrials.gov number NCT02766036. Registered: May 9, 2016).

Electronic supplementary material

The online version of this article (10.1186/s12882-019-1337-7) contains supplementary material, which is available to authorized users.

Chronic Kidney Disease and Cardiovascular Disease: Is there Any Relationship?

INTRODUCTION

Chronic Kidney Disease is a growing health burden world wide. Traditional and mutual risk factors between CVD and CKD are age, hypertension, diabetes mellitus, dyslipidemia, tobacco use, family history and male gender. In this review, we will focus on whether or not early CKD is an important risk factor for the presence, severity and progression of CVD. Specifically, we will examine both traditional and novel risk factors of both CKD and CVD and how they relate to each other.

CONCLUSION

We will also assess if early treatment of CKD, intensive compared to standard, has an important effect on the halt of the development of CKD as well as CVD. Insights into the pathogenesis and early recognition of CKD as well as the importance of novel kidney biomarkers will be pointed out. Also, common pathogenetic mechanisms between CKD and CVD will be discussed.

Dipstick proteinuria predicts all-cause mortality in general population: A study of 17 million Korean adults

Objective

A quantitative basis for the use of dipstick urinalysis for risk assessment of all-cause mortality is scarce. Therefore, we investigated the association between dipstick proteinuria and all-cause mortality in a general population and evaluated the effect of confounders on this association.

Methods

The study population included 17,342,956 adults who underwent health examinations between 2005 and 2008 under the National Health Insurance System. Proteinuria was determined using a single dipstick urinalysis, and the primary outcome of this study was all-cause mortality. The prognostic impact of proteinuria was assessed by constructing a multivariable Cox model.

Results

The mean age of the study population (53.24% male) was 46.06 years; 724,681 deaths from all causes occurred over a median follow-up period of 9.34 years (interquartile range 8.17–10.16), and the maximum follow-up was 12.12 years. After full adjustment for covariates, a higher level of dipstick proteinuria indicated a higher risk of all-cause death [Hazard ratios (95% confidence intervals); 1.22 (1.20–1.24), 1.47 (1.45–1.49), 1.81 (1.77–1.84), 2.32 (2.24–2.41), 2.74 (2.54–2.96); trace to 4+, respectively], and various subgroup analyses did not affect the main outcome for the total population. ≥1+ proteinuria in the group without metabolic diseases (hypertension, diabetes, dyslipidemia, or obesity) resulted in higher hazard ratios than those in the group with metabolic diseases and negative or trace proteinuria.

Conclusions

Our study showed a strong association between dipstick proteinuria and all-cause mortality in this nationwide population-based cohort in South Korea.

Two-year changes in proteinuria and risk for myocardial infarction in patients with hypertension: a prospective cohort study

OBJECTIVE

To assess whether changes in proteinuria are associated with the incidence of myocardial infarction (MI) in patients with hypertension.

METHODS

The Kailuan study was a prospective longitudinal cohort study on cardiovascular risk factors and events. Hazard ratios with 95% confidence intervals (CIs) were calculated using Cox regression models.

RESULTS

A total of 24 926 hypertensive patients (mean age: 55.2 ± 10.9 years) without previous MI were included. After a mean follow-up of 6.8 years, 382 (1.5%) individuals developed MI. Participants with proteinuria at baseline had a 60% higher risk for developing MI as compared with participants without proteinuria at baseline (hazard ratio: 1.60, 95% CI: 1.12-2.29) after adjusting for dyslipidemia, diabetes mellitus and other cardiovascular risk factors. Compared with participants without proteinuria, individuals with incident proteinuria or persistent proteinuria during the follow-up had 54 and 141% higher risks for developing MI, respectively (hazard ratio: 1.54, 95% CI: 1.14-2.09 and hazard ratio: 2.41, 95% CI: 1.59-3.66; all P < 0.05).

CONCLUSION

Proteinuria is associated with an increased incidence of MI, but the association is likely to be underestimated if baseline measurements of proteinuria are used. Measures of changes in proteinuria, particular persistent proteinuria, are more likely to reflect the lifetime risk for MI.

Association between Sarcopenia and Dipstick Proteinuria in the Elderly Population: The Korea National Health and Nutrition Examination Surveys 2009-2011

Background

Sarcopenia and proteinuria are significant health difficulties in the elderly; however, few studies have investigated their relationship. In this study, we investigated the association between sarcopenia and proteinuria in Korean subjects over 60 years old.

Methods

We included data from the Korean National Health and Nutrition Examination Survey, a cross-sectional, nationally representative survey conducted from 2009 to 2011 (n=4,008). Sarcopenia was defined using appendicular skeletal muscle mass as a percentage of body weight. Proteinuria was defined by a urine dipstick test result above trace levels.

Results

The overall proteinuria prevalence was 7.2%. The incidence of sarcopenia was significantly higher in subjects with proteinuria. The prevalence of proteinuria was significantly higher in the sarcopenic group (5.5% vs. 14.5% in the non-chronic kidney disease (CKD) group; 17.2% vs. 23.2% in the CKD group) than in the non-sarcopenic group. Furthermore, sarcopenic participants had worse metabolic parameters, such as higher body mass indexes, waist circumferences, and fasting glucose levels, and lower high-density lipoprotein cholesterol levels than those in the non-CKD group. After adjustment for confounders, the odds ratios (95% confidence interval) for proteinuria were 2.84 (1.92–4.18) in the sarcopenic non-CKD group, 3.70 (2.59–5.30) in the non-sarcopenic CKD group, and 5.19 (2.64–10.18) in the sarcopenic CKD group, compared to the non-sarcopenic, non-CKD group. Sarcopenia increased the proteinuria risk in elderly participants without CKD, even after adjustment for obesity, hypertension, diabetes, and metabolic syndrome.

Conclusion

These findings showed that sarcopenia was associated with dipstick proteinuria, especially in elderly participants without CKD, regardless of comorbidities.

Changes in Proteinuria on the Risk of All-Cause Mortality in People with Diabetes or Prediabetes: A Prospective Cohort Study

BACKGROUND

Proteinuria has been related to all-cause mortality, showing regression or progression. However, few studies have focused on the relationship between proteinuria changes and all-cause mortality. The main purpose of this paper is to examine the associations between proteinuria changes and all-cause mortality in people with diabetes or prediabetes.

METHODS

Dipstick proteinuria at baseline and a 2-year follow-up were determined in the participants attending the Kailuan prospective cohort study. Participants were then divided into three categories: elevated proteinuria, stable proteinuria, and reduced proteinuria. Four Cox proportional hazard models were built to access the relations of proteinuria changes to all-cause mortality, adjusting for other confounding covariates.

RESULTS

A total of 17,878 participants were finally included in this study. There were 1193 deaths after a median follow-up of 6.69 years. After adjusting for major covariates and proteinuria at baseline, mortality risk was significantly associated with elevated proteinuria (hazard ratio (HR): 1.54, 95% confidence interval (CI): 1.33-1.79) and reduced proteinuria (HR: 0.70, 95% CI: 0.55-0.89), compared to those with stable proteinuria.

CONCLUSION

Proteinuria changes were independently associated with mortality risk in either diabetic or prediabetic population.

Blood pressure components and the risk for proteinuria in Japanese men: The Kansai Healthcare Study

Background

We examined prospectively which of the four blood pressure (BP) components (systolic BP [SBP], diastolic BP [DBP], pulse pressure [PP], and mean arterial pressure [MAP]) was best in predicting the risk of proteinuria.

Methods

This prospective study included 9341 non-diabetic Japanese middle-aged men who had no proteinuria and an estimated glomerular filtration rate ≥60 mL/min/1.73 m² and were not taking antihypertensive medications at entry. Persistent proteinuria was defined if proteinuria was detected two or more times consecutively and persistently at the annual examination until the end of follow-up. We calculated the difference in values of Akaike's information criterion (ΔAIC) in comparison of the BP components-added model to the model without them in a Cox proportional hazards model.

Results

During the 84,587 person-years follow-up period, we confirmed 151 cases of persistent proteinuria. In multiple-adjusted models that included a single BP component, the hazard ratios for persistent proteinuria for the highest quartile of SBP, PP, and MAP were 3.11 (95% confidence interval [CI], 1.79–5.39), 1.87 (95% CI, 1.18–2.94), and 2.21 (95% CI, 1.33–3.69) compared with the lowest quartile of SBP, PP, and MAP, respectively. The hazard ratio for the highest quartile of DBP was 2.69 (95% CI, 1.65–4.38) compared with the second quartile of DBP. Of all models that included a single BP component, those that included SBP alone or DBP alone had the highest values of ΔAIC (14.0 and 13.1, respectively) in predicting the risk of persistent proteinuria.

Conclusions

Of all BP components, SBP and DBP were best in predicting the risk of persistent proteinuria in middle-aged Japanese men.

•

We examined which blood pressure (BP) components increased risk of proteinuria.

•

We used systolic BP, diastolic BP, pulse pressure, and mean arterial pressure.

•

Systolic and diastolic BP were the best predictors of persistent proteinuria.

Two-Year Changes in Proteinuria and the Risk of Stroke in the Chinese Population: A Prospective Cohort Study

Background

Whether changes in proteinuria are associated with incident stroke in the general population is unclear. This study aimed to investigate the association between changes in proteinuria and incident stroke and its subtypes.

Methods and Results

The current study included 60 940 Chinese participants (mean age, 50.69 years) who were free of stroke at the time of surveys (2006–2007 and 2008–2009). Participants were divided into 4 categories according to 2‐year changes in proteinuria: no proteinuria, remittent proteinuria, incident proteinuria, and persistent proteinuria. Cox proportional hazards models were used to calculate hazard ratios and their 95% CIs for stroke. After a median follow‐up period of 6.92 years, 1769 individuals developed stroke. After adjustment for confounding factors, incident proteinuria and persistent proteinuria were associated with increased risk of stroke (hazard ratio, 1.46 [95% CI, 1.26–1.68] and hazard ratio, 1.71 [95% CI, 1.42–2.06], respectively) compared with no proteinuria, which were higher than proteinuria detected at one single point (hazard ratio, 1.25; 95% CI, 1.09–1.43). The effect size for risk of stroke subtypes including ischemic stroke and hemorrhagic stroke was similar.

Conclusions

Changes in proteinuria exposure, particularly persistent proteinuria, are more likely to reflect the risk of stroke, compared with proteinuria collected at a single time point in the general population.

Renoprotective Effect of the Combination of Renin-angiotensin System Inhibitor and Calcium Channel Blocker in Patients with Hypertension and Chronic Kidney Disease

BACKGROUND

Renin-angiotensin system inhibitor and calcium channel blocker (CCB) are widely used in controlling blood pressure (BP) in patients with chronic kidney disease (CKD). We carried out a meta-analysis to compare the renoprotective effect of the combination of angiotensin-converting enzyme inhibitor (ACEI) or angiotensin receptor blocker (ARB) and CCB (i.e., ACEI/ARB + CCB) with ACEI/ARB monotherapy in patients with hypertension and CKD.

METHODS

Publications were identified from PubMed, Embase, Medline, and Cochrane databases. Only randomized controlled trials (RCTs) of BP lowering treatment for patients with hypertension and CKD were considered. The outcomes of end-stage renal disease (ESRD), cardiovascular events, BP, urinary protein measures, estimated glomerular filtration rate (GFR), and adverse events were extracted.

RESULTS

Based on seven RCTs with 628 patients, ACEI/ARB + CCB did not show additional benefit for the incidence of ESRD (risk ratio [RR] = 0.84; 95% confidence interval [CI]: 0.52-1.33) and cardiovascular events (RR = 0.58; 95% CI: 0.21-1.63) significantly, compared with ACEI/ARB monotherapy. There were no significant differences in change from baseline to the end points in diastolic BP (weighted mean difference [WMD] = -1.28 mmHg; 95% CI: -3.18 to -0.62), proteinuria (standard mean difference = -0.55; 95% CI: -1.41 to -0.30), GFR (WMD = -0.32 ml/min; 95% CI: -1.53 to -0.89), and occurrence of adverse events (RR = 1.05; 95% CI: 0.72-1.53). However, ACEI/ARB + CCB showed a greater reduction in systolic BP (WMD = -4.46 mmHg; 95% CI: -6.95 to -1.97), compared with ACEI/ARB monotherapy.

CONCLUSION

ACEI/ARB + CCB had no additional renoprotective benefit beyond than what could be achieved with ACEI/ARB monotherapy.

Genetic risk score and risk of stage 3 chronic kidney disease

BACKGROUND

We developed a genetic risk score (GRS) and examined whether the GRS may predict incident stage 3 chronic kidney disease (CKD) independent of common clinical risk factors.

METHOD

The present study included 2,698 individuals who attended the 15th (1977 to 1979) and the 24th exams (1995 to 1998) in the Framingham Original cohort or the 6th (1995 to 1998) and the 8th exams (2005 to 2008) in the Framingham Offspring cohort. A weighted GRS was constructed combining 53 single nucleotide polymorphisms (SNPs) associated with lower creatinine-based estimated glomerular filtration rate (eGFR). Stage 3 CKD was defined as eGFR <60 mL/min/1.73 m2, and incident cases were identified at follow-up after excluding prevalent cases at baseline.

RESULTS

A total of 292 incident cases and 2,406 non-cases were identified over, on average, 11 years of follow-up. After adjustment for sex, age, cohort, baseline eGFR, hypertension, diabetes, and dipstick proteinuria, the odds ratio of incident stage 3 CKD was 1.37 (95%CI: 1.02-1.83) per 10 alleles of the GRS (P = 0.04). There was no statistically significant difference between the C-statistic without and with inclusion of the GRS (0.783 and 0.785, respectively; P = 0.39).

CONCLUSIONS

A GRS developed based on 53 SNPs associated with reduced eGFR was prospectively associated with incident stage 3 CKD. However, this score did not substantially improve discrimination of stage 3 CKD beyond the common clinical risk factors.

Prevalence and risk factors for cardiovascular disease among chronic kidney disease patients: results from the Chinese cohort study of chronic kidney disease (C-STRIDE)

BACKGROUND

Although a high incidence of cardiovascular disease (CVD) is observed among chronic kidney disease (CKD) patients in developed countries, limited information is available about CVD prevalence and risk factors in the Chinese CKD population. The Chinese Cohort of Chronic Kidney Disease (C-STRIDE) was established to investigate the prevalence and risk factors of CVD among Chinese CKD patients.

METHODS

Participants with stage 1-4 CKD (18-74 years of age) were recruited at 39 clinical centers located in 28 cities from 22 provinces of China. At entry, the socio-demographic status, medical history, anthropometric measurements and lifestyle behaviors were documented, and blood and urine samples were collected. Estimated glomerular filtration rate (eGFR) was calculated by the CKD-EPI creatinine equation. CVD diagnosis was based on patient self-report and review of medical records by trained staff. A multivariable logistic regression model was used to estimate the association between risk factors and CVD.

RESULTS

Three thousand four hundred fifty-nine Chinese patients with pre-stage 5 CKD were enrolled, and 3168 finished all required examinations and were included in the study. In total, 40.8% of the cohort was female, with a mean age of 48.21 ± 13.70 years. The prevalence of CVD was 9.8%, and in 69.1% of the CVD cases cerebrovascular disease was observed. Multivariable analysis showed that increasing age, lower eGFR, presence of hypertension, abdominal aorta calcification and diabetes were associated with comorbid CVD among CKD patients. The odds ratios and 95% confidence intervals for these risk factors were 3.78 (2.55-5.59) for age 45-64 years and 6.07 (3.89-9.47) for age ≥65 years compared with age <45 years; 2.07 (1.28-3.34) for CKD stage 3a, 1.66 (1.00-2.62) for stage 3b, and 2.74 (1.72-4.36) for stage 4 compared with stages 1 and 2; 2.57 (1.50-4.41) for hypertension, 1.82 (1.23-2.70) for abdominal aorta calcification, and 1.70 (1.30-2.23) for diabetes, respectively.

CONCLUSIONS

We reported the CVD prevalence among a CKD patient cohort and found age, hypertension, diabetes, abdominal aorta calcification and lower eGFR were independently associated with higher CVD prevalence. Prospective follow-up and longitudinal evaluations of CVD risk among CKD patients are warranted.

Association between Overall Lifestyle Changes and the Incidence of Proteinuria: A Population-based, Cohort Study

Objective This study aimed to examine the association between the changes in an overall healthy lifestyle, as quantified by the number of unhealthy lifestyle factors and obesity status, and the incidence of proteinuria in the general Japanese population. Methods A retrospective cohort study was conducted among 99,404 (men, 36.9%) participants aged from 40-74 years of age who underwent two health check-ups with a 1-year interval in Japan between 2008 and 2009. Any participants with chronic kidney disease at baseline were excluded. The smoking status, body mass index, physical activity, alcohol consumption, and healthy eating habits were combined into a simple overall healthy lifestyle score ranging from 0 to 5. The changes in overall healthy lifestyle scores from baseline (range, -5 to +5) and the incidence of proteinuria, defined by a dipstick urinalysis (score ≥1+), were assessed at the second check-up. A logistic regression analysis was used to examine the association between the changes in overall healthy lifestyle scores and the incidence of proteinuria. Results After one year of follow-up, 3.9% of men and 2.4% of women developed proteinuria. Each increase (or decrease) in the changes in overall healthy lifestyle scores was associated with a reduced (or increased) risk of proteinuria in both men (odds ratio (OR) 0.87; 95% confidence interval (CI), 0.81-0.94) and women (OR 0.87; 95%CI, 0.80-0.94) after adjusting for age, baseline lifestyle scores, hypertension, diabetes mellitus, and hypercholesterolemia. Stratified analyses based on age, the presence or absence of hypertension, or diabetes mellitus revealed similar results. Conclusion Overall lifestyle changes, even within a year, were found to influence the incidence of proteinuria.

Microalbuminuria, cardiovascular risk factors and cardiovascular morbidity in a British population: The EPIC-Norfolk Population-based Study

BACKGROUND

Microalbuminuria is independently associated with increased cardiovascular risk and renal function deterioration in diabetes and hypertension, but the clinical relevance of raised albuminuria in the general population is less certain. We examined the prevalence of microalbuminuria and its relationship to cardiovascular risk factors and cardiovascular morbidity in the UK general population.

METHODS

Cross-sectional population-based study of 23,964 individuals, aged 40-79 years recruited in 1993-1997 for the EPIC-Norfolk Study. Smoking status, prevalent physician diagnosed diabetes, hypertension, cardiovascular disease and cancer were derived from a health and lifestyle questionnaire. Albumin-to-creatinine ratios were estimated from random spot urine specimens collected at the survey visit, and using these ratios participants were categorized into normoalbuminuria, microalbuminuria (2.5-25 mg/mmol), and macroalbuminuria.

RESULTS

The prevalence of microalbuminuria and macroalbuminuria was 11.8% and 0.9% respectively in the total population and significantly higher in women (14.4%) compared with men (8.9%) (P<0.001). Independent determinants of microalbuminuria were age, sex, systolic blood pressure and current smoking. Microalbuminuria was independently associated with cardiovascular morbidity, after adjusting for known cardiovascular risk factors, with odds ratio (95% confidence interval) for prevalent cardiovascular disease of 1.30 (1.12-1.51) in all men and women.

CONCLUSION

Microalbuminuria was present in approximately 12% of this population. It was independently associated with cardiovascular risk factors and prevalent cardiovascular disease. Microalbuminuria may be a useful indicator of high absolute cardiovascular risk in the community but prospective data are needed to establish its independent predictive value for future events.

Association of albuminuria with all-cause and cardiovascular disease mortality in diabetes: the Strong Heart Study

Objectives — To estimate the relative risks of albuminuria with all-cause and cardiovascular disease (CVD) mortality in a large cohort of American Indians with diabetes. Methods — A total of 1,953 diabetic participants in the Strong Heart Study were evaluated based on albuminuria categories at baseline examination. The Cox proportional hazards model was used to examine associations. Results — Of the 1,953 participants, 605 (31%) and 410 (21%) had microalbuminuria and macroalbuminuria, respectively, at baseline examination. Microalbuminuria (HR=1.42, 95% CI 1.15—1.77 for all-cause, and HR=1.48, CI 1.01—2.17 for CVD), and macroalbuminuria (HR=3.39, CI 2.71—4.25 for all-cause, and HR=3.74, CI 2.56—5.47 for CVD) were significant predictors for all-cause and CVD mortality after adjustment for other CVD risk factors. Conclusions — Results from the present study suggest that albuminuria is a strong independent predictor of all-cause and CVD Mortality in American Indians with diabetes.

Dietary Guideline Adherence Index and Kidney Measures in the Framingham Heart Study

BACKGROUND

No observational studies have directly considered dietary guidelines when examining the prospective association between dietary intake and kidney measures.

STUDY DESIGN

Prospective cohort study.

SETTING & PARTICIPANTS

We examined participants who attended examinations 7 (1998-2001) and 8 (2005-2008) in the Framingham Offspring Cohort.

PREDICTORS

Individual components of Dietary Guidelines for Americans Adherence Index (DGAI) that reflect adherence to key dietary recommendations based on the 2005 guideline.

OUTCOMES & MEASURES

The primary outcome was incident low estimated glomerular filtration rate (eGFR) at follow-up after exclusion of prevalent low eGFR at baseline. Low eGFR was defined as serum creatinine-based eGFR<60mL/min/1.73m².

RESULTS

Among 1,822 participants (mean age, 59.4 years; 54.6% women), 181 incident cases of low eGFR were identified. After adjustment for potential confounders, compared to optimal adherence to meat and legume recommendations, low adherence was associated with higher odds of incident low eGFR (P for trend = 0.01); ORs in the lowest and intermediate adherence categories were 2.98 (95% CI, 1.13-7.92) and 1.65 (95% CI, 1.02-2.66), respectively. Low adherence to dairy product recommendations was also associated with higher odds of incident low eGFR compared to optimal adherence (P for trend = 0.03); ORs in the lowest and intermediate adherence categories were 1.98 (95% CI, 1.03-3.82) and 1.59 (95% CI, 0.81-3.11), respectively. In addition, low adherence to meat and legume recommendations was associated with rapid eGFR decline (P for trend = 0.01), and low adherence to dairy product recommendations was associated with rapid eGFR decline (P for trend = 0.01) and incident albuminuria (P for trend = 0.03).

LIMITATIONS

The DGAI was developed based on the 2005 Dietary Guidelines for Americans.

CONCLUSIONS

Better adherence to dietary recommendations for both meat and legumes and dairy products was associated with lower risk for developing adverse kidney measures.

Stop chronic kidney disease progression: Time is approaching

Progression of chronic kidney disease (CKD) is inevitable. However, the last decade has witnessed tremendous achievements in this field. Today we are optimistic; the dream of withholding this progression is about to be realistic. The recent discoveries in the field of CKD management involved most of the individual diseases leading the patients to end-stage renal disease. Most of these advances involved patients suffering diabetic kidney disease, chronic glomerulonephritis, polycystic kidney disease, renal amyloidosis and chronic tubulointerstitial disease. The chronic systemic inflammatory status and increased oxidative stress were also investigated. This inflammatory status influences the anti-senescence Klotho gene expression. The role of Klotho in CKD progression together with its therapeutic value are explored. The role of gut as a major source of inflammation, the pathogenesis of intestinal mucosal barrier damage, the role of intestinal alkaline phosphatase and the dietary and therapeutic implications add a novel therapeutic tool to delay CKD progression.

Kidney disease in antiretroviral-naïve HIV-positive adults with high CD4 counts: prevalence and predictors of kidney disease at enrolment in the INSIGHT Strategic Timing of AntiRetroviral Treatment (START) trial

OBJECTIVES

HIV infection has been associated with an increased risk of chronic kidney disease (CKD). Little is known about the prevalence of CKD in individuals with high CD4 cell counts prior to initiation of antiretroviral therapy (ART). We sought to address this knowledge gap.

METHODS

We describe the prevalence of CKD among 4637 ART-naïve adults (mean age 36.8 years) with CD4 cell counts > 500 cells/μL at enrolment in the Strategic Timing of AntiRetroviral Treatment (START) study. CKD was defined by estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m(2) and/or dipstick urine protein ≥ 1+. Logistic regression was used to identify baseline characteristics associated with CKD.

RESULTS

Among 286 [6.2%; 95% confidence interval (CI) 5.5%, 6.9%] participants with CKD, the majority had isolated proteinuria. A total of 268 participants had urine protein ≥ 1+, including 41 with urine protein ≥ 2+. Only 22 participants (0.5%) had an estimated glomerular filtration rate < 60 mL/min/1.73 m(2) , including four who also had proteinuria. Baseline characteristics independently associated with CKD included diabetes [adjusted odds ratio (aOR) 1.73; 95% CI 1.05, 2.85], hypertension (aOR 1.82; 95% CI 1.38, 2.38), and race/ethnicity (aOR 0.59; 95% CI 0.37, 0.93 for Hispanic vs. white).

CONCLUSIONS

We observed a low prevalence of CKD associated with traditional CKD risk factors among ART-naïve clinical trial participants with CD4 cell counts > 500 cells/μL.

Dipstick proteinuria as a predictor of all-cause and cardiovascular disease mortality in Bangladesh: A prospective cohort study

OBJECTIVE

Baseline, persistent, incident, and remittent dipstick proteinuria have never been tested as predictors of mortality in an undeveloped country. The goal of this study was to determine which of these four types of proteinuria (if any) predict mortality.

METHODS

Baseline data was collected from 2000 to 2002 in Bangladesh from 11,121 adults. Vital status was ascertained over 11-12years. Cox models were used to evaluate proteinuria in relation to all-cause and cardiovascular disease (CVD) mortality. CVD mortality was evaluated only in those with baseline proteinuria. Persistent, remittent, and incident proteinuria were determined at the 2-year exam.

RESULTS

Baseline proteinuria of 1+ or greater was significantly associated with all-cause (hazard ratio (HR) 2.87; 95% C.I., 1.71-4.80) and CVD mortality (HR: 3.55; 95% C.I., 1.81-6.95) compared to no proteinuria, adjusted for age, gender, arsenic well water concentration, education, hypertension, BMI, smoking, and diabetes mellitus. Persistent 1+ proteinuria had a stronger risk of death, 3.49 (1.64-7.41)-fold greater, than no proteinuria. Incident 1+ proteinuria had a 1.87 (0.92-3.78)-fold greater mortality over 9-10years. Remittent proteinuria revealed no increased mortality.

CONCLUSIONS

Baseline, persistent, and incident dipstick proteinuria were predictors of all-cause mortality with persistent proteinuria having the greatest risk. In developing countries, those with 1+ dipstick proteinuria, particularly if persistent, should be targeted for definitive diagnosis and treatment. The two most common causes of proteinuria to search for are diabetes mellitus and hypertension.

Resolution of low-grade proteinuria is associated with improved outcomes after renal transplantation-a retrospective longitudinal study

Low-grade proteinuria and systolic hypertension (SHT) are risk factors for allograft failure. Both are dynamic variables and their relationship is not independent. We have simultaneously analyzed the effects of proteinuria and SHT on graft outcomes in 805 adult Kidney Transplant Recipients and impact of their changes over time. Proteinuria and systolic blood pressure (SBP) were recorded for years 1 and 3 posttransplantation. Subjects with proteinuria >1 g/day were excluded. Patients were divided into groups based on proteinuria (Absent(A) <150 mg/day or low-grade(P)150 mg-1 g/day) and blood pressure (Normotensive-SBP <140 mmHg or hypertensive-SBP ≥ 140 mmHg). Graft survival was assessed in all four groups over 10 years by multivariate analysis. At the three annual time points (Year 1, 2 and 3) hypertensive patients with proteinuria had the worst graft survival. Patients with persistent proteinuria between years 1-2 and 2-3 had the poorest graft survival with an improvement if proteinuria regressed (P-A), especially in the Hypertensive group. The impact of proteinuria was highest in persistently hypertensive patients between years 1-3. Thus both proteinuria and SHT were associated with poor graft survival and the combination of the two led to the worst outcomes. Importantly, SHT was associated with significantly worse outcomes in patients with proteinuria. Patient cohort with SHT and low-grade proteinuria represent a selective group that might benefit from intervention.

Race and other risk factors for incident proteinuria in a national cohort of HIV-infected veterans

BACKGROUND

Proteinuria in human immunodeficiency virus (HIV)-infected individuals has been associated with poorer outcomes. We examined risk factors associated with the development of proteinuria in a national registry of HIV-infected veterans.

METHODS

A total of 21,129 HIV-infected veterans of black and white race without preexisting kidney disease were receiving health care in the Veterans' Health Administration (VHA) medical system between 1997 and 2011. Using the VHA electronic record system, we identified kidney-related risk factors (hypertension, diabetes, and cardiovascular disease) and HIV-related risk factors (CD4 lymphocyte count, HIV RNA level, hepatitis C virus, and hepatitis B virus) for developing proteinuria. Proteinuria was defined by 2 consecutive dipstick measures of 1 or higher. The Fine-Gray competing risk model was used to estimate association between clinical variables and incident proteinuria, while accounting for intervening mortality events.

RESULTS

During follow-up (median = 5.3 years), 7031 patients developed proteinuria. Overall, black race compared with white race was associated with a higher risk of proteinuria {hazard ratio [95% confidence interval (CI)] = 1.51 [1.43 to 1.59]}, but the association was stronger at younger ages (P interaction <0.001). Age-stratified risk of proteinuria for blacks relative to whites was greatest among veterans <30 years [2.19 (1.66 to 2.89)] and the risk diminished with increasing age [1.14 (0.97 to 1.34) for >60 years]. We found the race difference to be stronger for the outcome of 2 or higher proteinuria [2.13 (1.89 to 2.39)]. Both HIV-related and traditional risk factors were also associated with incident proteinuria (P < 0.05).

CONCLUSIONS

Compared with whites, risk of proteinuria was higher in black veterans with HIV infection, particularly at younger ages. In both races, HIV- and kidney-related risk factors were associated with higher proteinuria risk.

Diagnostic accuracy of urine dipstick for proteinuria in older outpatients

BACKGROUND

The urine dipstick is widely used as an initial screening tool for the evaluation of proteinuria; however, its diagnostic accuracy has not yet been sufficiently evaluated. Therefore, we evaluated its diagnostic accuracy using spot urine albumin/creatinine ratio (ACR) and total protein/creatinine ratio (PCR) in proteinuria.

METHODS

Using PCR ≥0.2 g/g or ≥0.5 g/g and ACR ≥300 mg/g or ≥30 mg/g as the reference standard, we calculated the diagnostic accuracy profile: sensitivity, specificity, positive and negative predictive value, and the area under the curve (AUC) of the receiver operating characteristic curve.

RESULTS

PCR and ACR were available for 10,348 and 3,873 instances of dipstick testing. The proportions with PCR ≥0.2 g/g, ≥0.5 g/g and ACR ≥300 mg/g, ≥30 mg/g were 38.2%, 24.6% and 8.9%, 31.7%, respectively. The AUCs for PCR ≥0.2 g/g, ≥0.5 g/g, and ACR ≥300 mg/g were 0.935 (trace: closest to ideal point), 0.968 (1+), and 0.983 (1+), respectively. Both sensitivity and specificity were >80% except for PCR ≥0.5 g/g with trace cutoff. For the reference standard of ACR ≥30 mg/g, the AUC was 0.797 (trace) and the sensitivity was 63.5%.

CONCLUSION

Urine dipstick test can be used for screening in older outpatients with ACR ≥300 mg/g or PCR as the reference standard for proteinuria. However, we cannot recommend the test as a screening tool with ACR ≥30 mg/g as the reference owing to its low sensitivity.

Proteinuria in midlife and 39-year total mortality: the Honolulu Heart Program

BACKGROUND

Previous population-based studies have shown that proteinuria is an independent predictor of total mortality. However, no studies have examined multiple proteinuria measurements or had a follow-up period longer than two decades.

METHODS

Proteinuria was measured by urine dipstick on 6,815 Japanese-American men on two occasions, 6 years apart. Participants were classified into the "no proteinuria" group if both examinations were negative, "transient proteinuria" if either was positive, and "persistent proteinuria" if both were positive and followed for total mortality over 39 years.

RESULTS

Prevalence of transient and persistent proteinuria was 6.4% and 1.3%, respectively. Age-adjusted total mortality rates were 41.9, 55.0, and 71.9 per 1000 person-years follow-up for no, transient, and persistent proteinuria groups, respectively (p for trend <.0001). Multivariate Cox proportional hazards models showed increased total mortality risk in a dose-response manner: HR, 1.40; P < .001 and HR, 2.26; P < .001 for transient and persistent proteinuria groups, respectively (using no proteinuria as reference). Stratified analyses showed stronger associations between proteinuria and mortality among those with prevalent cardiovascular diseases compared with those without.

CONCLUSIONS

Proteinuria was independently associated with higher total mortality risk over 39 years. This risk was stronger among high-risk populations but also remained significant in low-risk populations. Simple urine dipstick can be a good risk assessment tool in the general population.

Proteinuria and its relation to cardiovascular disease

Chronic kidney disease (CKD) and its associated morbidity pose a worldwide health problem. As well as risk of endstage renal disease requiring renal replacement therapy, cardiovascular disease is the leading cause of premature death among the CKD population. Proteinuria is a marker of renal injury that can often be detected earlier than any tangible decline in glomerular filtration rate. As well as being a risk marker for decline in renal function, proteinuria is now widely accepted as an independent risk factor for cardiovascular morbidity and mortality. This review will address the prognostic implications of proteinuria in the general population as well as other specific disease states including diabetes, hypertension and heart failure. A variety of pathophysiological mechanisms that may underlie the relationship between renal and cardiovascular disease have been proposed, including insulin resistance, inflammation, and endothelial dysfunction. As proteinuria has evolved into a therapeutic target for cardiovascular risk reduction in the clinical setting we will also review therapeutic strategies that should be considered for patients with persistent proteinuria.

Proteinuria and rate of change in kidney function in a community-based population

Proteinuria identifies patients at risk for adverse clinical outcomes, but it is unclear whether proteinuria correlates with the rate of renal decline. We examined the association between proteinuria and rate of change in estimated GFR (eGFR) in a cohort of 638,150 adults from a province-wide registry in Alberta, Canada, who had a measure of proteinuria and three or more outpatient serum creatinine measurements over a period of ≥1 year. An adjusted sex-specific linear mixed-effects model was used to determine the rate of change in eGFR per year for patients with normal, mild, and heavy proteinuria, stratified by baseline kidney function (eGFR ≥90, 60-89.9, 45-59.9, 30-44.9, and 15-29.9 ml/min per 1.73 m(2)). In men, heavy proteinuria and a baseline eGFR of 45-59.9 ml/min per 1.73 m(2) correlated with a change in eGFR of -2.16 (95% confidence interval [CI], -2.37 to -1.95) ml/min per 1.73 m(2) per year, whereas mild proteinuria and a baseline eGFR of 30-44.9 ml/min per 1.73 m(2) correlated with a change in eGFR of -0.51 (95% CI, -0.70 to -0.32) ml/min per 1.73 m(2) per year. Similar trends were observed for female, elderly, and diabetic patients. Notably, normal protein levels and a lower baseline eGFR (15-29.9 ml/min per 1.73 m(2)) correlated with stable or improved renal function. In conclusion, our results suggest that proteinuria of increasing severity is associated with a faster rate of renal decline, regardless of baseline eGFR, and the combined effect should be considered in patients with CKD.

Elevated galectin-3 precedes the development of CKD

Galectin-3, a profibrotic mediator, is linked to the development of renal fibrosis in animal models and inversely correlates with GFR in humans, but whether galectin-3 predicts incident kidney disease is unknown. Here, we assessed renal outcomes for 2450 Framingham Offspring participants who attended examination 6 (1995-1998) and had follow-up data at examination 8 (2005-2008). Renal outcomes of interest included rapid decline in renal function (≥3 ml/min per 1.73 m(2) per year decline in estimated GFR [eGFR]), CKD (eGFR < 60 ml/min per 1.73 m(2)), and albuminuria (albumin-to-creatinine ratio ≥17 mg/g in men or ≥25 mg/g in women). We used multivariable logistic regression models to evaluate associations between galectin-3 with incident renal outcomes at examination 8. During a mean follow-up of 10.1 years, GFR declined rapidly in 241 (9.2%) participants, incident CKD developed in 277 (11.3%), and albuminuria developed in 194 (10.1%). Higher plasma levels of galectin-3 were associated with rapid decline in eGFR (per 1-SD log-galectin-3; adjusted odds ratio [OR], 1.49; 95% confidence interval [CI], 1.28 to 1.73]) and a higher risk of incident CKD (OR, 1.47; 95% CI, 1.27 to 1.71), but not with the risk of incident albuminuria. The addition of galectin-3 to clinical predictors improved the C-statistic (0.837-0.845; P=0.02) but did not reach predefined thresholds for clinically significant improvements to risk prediction based on reclassification indices. In conclusion, elevated levels of plasma galectin-3 are associated with increased risks of rapid GFR decline and of incident CKD in the community, which calls for further study in higher-risk groups.

Inhibition of the renin-angiotensin system for lowering coronary artery disease risk

The renin-angiotensin system when activated exerts proliferative and pro-inflammatory actions and thereby contributes to progression of atherosclerosis, including that occurring in the coronary arteries. It thus contributes as well to coronary artery disease (CAD). Several clinical trials have examined effects of renin-angiotensin system inhibition for primary and secondary prevention of coronary heart disease. These include important trials such as HOPE, EUROPA and PEACE using angiotensin converting enzyme inhibitors, VALIANT, OPTIMAAL and TRANSCEND using angiotensin receptor blockers, and the ongoing TOPCAT study in patients with preserved ejection fraction heart failure, many of who also have coronary artery disease. Data are unavailable as yet of effects of either direct renin inhibitors or the new angiotensin receptor/neprilysin inhibitor agents. Today, inhibition of the renin-angiotensin system is standard-of-care therapy for lowering cardiovascular risk in secondary prevention in high cardiovascular risk subjects.

Factors related to nephrotic-range proteinuria in late-stage chronic kidney disease patients with diabetes mellitus

PURPOSE

Diabetic nephropathy and proteinuria are important risk factors for both end-stage renal disease and cardiovascular events. The present study aimed to identify the factors associated with nephrotic-range proteinuria in patients with advanced diabetic nephropathy.

METHODS

This cross-sectional study enrolled 386 diabetic patients with chronic kidney disease (CKD) stages 3-5, from our outpatient Department of Nephrology. Urinary protein-to-creatinine ratio was recorded. Additionally, other laboratory parameters, body mass index, blood pressure, comorbidities, and medications were also reviewed.

RESULTS

The mean age of the patients was 65.1 ± 11.6 years. Among patients with CKD stage 3 and 4, the odds ratio (OR) for nephrotic-range proteinuria in relation with systolic blood pressure significantly increased starting from 121 mmHg (OR 7.04 and 11.79 for systolic blood pressure of 121-140 and ≥141 mmHg, respectively, in comparison with systolic blood pressure below 121 mmHg). In addition, serum phosphorus ≥4.7 mg/dl was associated with significantly higher risk (OR 15.45) for severe proteinuria, compared with a phosphorus level ≤2.6 mg/dl. Finally, hypertriglyceridemia ≥241 mg/dl was also associated with higher OR for severe proteinuria, compared with a triglyceride level ≤200 mg/dl. Similar associations were found in patients with CKD stage 5.

CONCLUSIONS

Higher systolic blood pressure, serum phosphorus, and triglyceride levels are associated with nephrotic-range proteinuria in patients with diabetic nephropathy and CKD stage 3-5. Further studies should clarify whether a reduction in serum phosphorus would lead to a decrease in proteinuria in these patients.

Losartan/hydrochlorothiazide combination vs. high-dose losartan in patients with morning hypertension--a prospective, randomized, open-labeled, parallel-group, multicenter trial

The treatment of morning hypertension has not been established. We compared the efficacy and safety of a losartan/hydrochlorothiazide (HCTZ) combination and high-dose losartan in patients with morning hypertension. A prospective, randomized, open-labeled, parallel-group, multicenter trial enrolled 216 treated outpatients with morning hypertension evaluated by home blood pressure (BP) self-measurement. Patients were randomly assigned to receive a combination therapy of 50 mg losartan and 12.5 mg HCTZ (n=109) or a high-dose therapy with 100 mg losartan (n=107), each of which were administered once every morning. Primary efficacy end points were morning systolic BP (SBP) level and target BP achievement rate after 3 months of treatment. At baseline, BP levels were similar between the two therapy groups. Morning SBP was reduced from 150.3±10.1 to 131.5±11.5 mm Hg by combination therapy (P<0.001) and from 151.0±9.3 to 142.5±13.6 mm Hg by high-dose therapy (P<0.001). The morning SBP reduction was greater in the combination therapy group than in the high-dose therapy group (P<0.001). Combination therapy decreased evening SBP from 141.6±13.3 to 125.3±13.1 mm Hg (P<0.001), and high-dose therapy decreased evening SBP from 138.9±9.9 to 131.4±13.2 mm Hg (P<0.01). Although both therapies improved target BP achievement rates in the morning and evening (P<0.001 for both), combination therapy increased the achievement rates more than high-dose therapy (P<0.001 and P<0.05, respectively). In clinic measurements, combination therapy was superior to high-dose therapy in reducing SBP and improving the achievement rate (P<0.001 and P<0.01, respectively). Combination therapy decreased urine albumin excretion (P<0.05) whereas high-dose therapy reduced serum uric acid. Both therapies indicated strong adherence and few adverse effects (P<0.001). In conclusion, losartan/HCTZ combination therapy was more effective for controlling morning hypertension and reducing urine albumin than high-dose losartan.

A risk score for chronic kidney disease in the general population

BACKGROUND

Stratification of individuals at risk for chronic kidney disease may allow optimization of preventive measures to reduce disease incidence and complications. We sought to develop a risk score that estimates an individual's absolute risk of incident chronic kidney disease.

METHODS

Framingham Heart Study participants free of baseline chronic kidney disease, who attended a baseline examination in 1995-1998 and follow-up in 2005-2008, were included in the analysis (n = 2490). Chronic kidney disease was defined as an estimated glomerular filtration rate <60 mL/min/1.73 m(2) using the Modification of Diet in Renal Disease equation. Participants were assessed for the development of chronic kidney disease at 10 years follow-up. Stepwise logistic regression was used to identify chronic kidney disease risk factors, and these were used to construct a risk score predicting 10-year chronic kidney disease risk. Performance characteristics were assessed using calibration and discrimination measures. The final model was externally validated in the bi-ethnic Atherosclerosis Risk in Communities Study (n = 1777).

RESULTS

There were 1171 men and 1319 women at baseline, and the mean age was 57.1 years. At follow-up, 9.2% (n = 229) had developed chronic kidney disease. Age, diabetes, hypertension, baseline estimated glomerular filtration rate, and albuminuria were independently associated with incident chronic kidney disease (P <.05), and these covariates were incorporated into a risk function (c-statistic 0.813). In external validation in the ARIC study, the c-statistic was 0.74 in whites (n = 1353) and 0.75 in blacks (n = 424).

CONCLUSION

Risk stratification for chronic kidney disease is achievable using a risk score derived from clinical factors that are readily accessible in primary care. The utility of this score in identifying individuals in the community at high risk of chronic kidney disease warrants further investigation.

Multiple versus single and other estimates of baseline proteinuria status as predictors of adverse outcomes in the general population

BACKGROUND

The association of proteinuria and adverse clinical outcomes is well established. The optimal method of classifying proteinuria status for study participants in whom it is measured multiple times is unknown, especially when the frequency of measurement varies between participants.

STUDY DESIGN

Population-based longitudinal study.

SETTING & PARTICIPANTS

All adults with at least one outpatient serum creatinine measurement in the province of Alberta, Canada.

FACTOR

Proteinuria (dipstick, albumin-creatinine ratio [ACR]).

OUTCOMES

All-cause mortality, end-stage renal disease, or doubling of serum creatinine level.

MEASURES

All outpatient urine dipstick and ACR measurements in the 6-month period before and after the first (index) estimated glomerular filtration rate were used to establish baseline proteinuria. Dipstick measures were analyzed as ceiling (median value up to the next integer), floor (median value down to the next integer), high (single highest dipstick value), low (single lowest dipstick value), and first (first available dipstick value only). Measurements of ACR were evaluated similarly and a median (median of all ACR measurements) value was added.

RESULTS

Of 920,985 participants, 17% (n = 160,548) had multiple dipstick urinalysis measurements and 22% (n = 22,814) had multiple ACR measurements. With single measurements, absolute rates of mortality and renal outcomes were lower in every proteinuria category compared with multiple measurements. In contrast, the relative increase in rate ratio was greater with increasing proteinuria in patients with single measurements compared with those with multiple measurements. In all classification systems evaluated, more severe proteinuria was associated with significantly higher rates of both outcomes (all P for trend <0.001).

LIMITATIONS

Lack of a gold standard for choosing between methods.

CONCLUSIONS

Rates of adverse outcomes related to multiple baseline proteinuria/albuminuria measurements were similar, independent of the measure of baseline proteinuria that was used to combine results. In contrast, discarding follow-up measurements and relying on only the first measurement led to lower estimates of absolute and relative risk for each proteinuria category.