Progression of kidney dysfunction in the community-dwelling elderly

Population-based reference values for kidney function and kidney function decline in 25- to 95-year-old Germans without and with diabetes

Understanding normal aging of kidney function is pivotal to help distinguish individuals at particular risk for chronic kidney disease. Glomerular filtration rate (GFR) is typically estimated via serum creatinine (eGFRcrea) or cystatin C (eGFRcys). Since population-based age-group-specific reference values for eGFR and eGFR-decline are scarce, we aimed to provide such reference values from population-based data of a wide age range. In four German population-based cohorts (KORA-3, KORA-4, AugUR, DIACORE), participants underwent medical exams, interview, and blood draw up to five times within up to 25 years. We analyzed eGFRcrea and eGFRcys cross-sectionally and longitudinally (12,000 individuals, age 25-95 years). Cross-sectionally, we found age-group-specific eGFRcrea to decrease approximately linearly across the full age range, for eGFRcys up to the age of 60 years. Within age-groups, there was little difference by sex or diabetes status. Longitudinally, linear mixed models estimated an annual eGFRcrea decline of -0.80 [95% confidence interval -0.82, -0.77], -0.79 [-0.83, -0.76], and -1.20 mL/min/1.73m2 [-1.33, -1.08] for the general population, "healthy" individuals, or individuals with diabetes, respectively. Reference values for eGFR using cross-sectional data were shown as percentile curves for "healthy" individuals and for individuals with diabetes. Reference values for eGFR-decline using longitudinal data were presented as 95% prediction intervals for "healthy" individuals and for individuals with diabetes, obesity, and/or albuminuria. Thus, our results can help clinicians to judge eGFR values in individuals seen in clinical practice according to their age and to understand the expected range of annual eGFR-decline based on their risk profile.

Treatment of chronic kidney disease in older populations

As the world population ages, an expected increase in the prevalence of chronic kidney disease (CKD) among older individuals will pose a considerable challenge for health care systems in terms of resource allocation for disease management. Treatment strategies for older patients with CKD should ideally align with those applied to the general population, focusing on minimizing cardiovascular events and reducing the risk of progression to kidney failure. Emerging therapies, such as SGLT-2 inhibitors and GLP-1 receptor agonists, hold promise for the effective management of CKD in older individuals. In addition, non-pharmacological interventions such as nutritional and exercise therapies have a crucial role. These interventions enhance the effects of pharmacotherapy and, importantly, contribute to the maintenance of cognitive function and overall quality of life. Various factors beyond age and cognitive function must be taken into account when considering kidney replacement therapy for patients with kidney failure. Importantly, all treatment options, including dialysis, transplantation and conservative management approaches, should be tailored to the individual through patient-centred decision-making. The dynamic integration of digital technologies into medical practice has the potential to transform the management of CKD in the aging population.

Accuracy of glomerular filtration rate estimation using creatinine and cystatin C for identifying and monitoring moderate chronic kidney disease: the eGFR-C study

Background

Estimation of glomerular filtration rate using equations based on creatinine is widely used to manage chronic kidney disease. In the UK, the Chronic Kidney Disease Epidemiology Collaboration creatinine equation is recommended. Other published equations using cystatin C, an alternative marker of kidney function, have not gained widespread clinical acceptance. Given higher cost of cystatin C, its clinical utility should be validated before widespread introduction into the NHS.

Objectives

Primary objectives were to: (1) compare accuracy of glomerular filtration rate equations at baseline and longitudinally in people with stage 3 chronic kidney disease, and test whether accuracy is affected by ethnicity, diabetes, albuminuria and other characteristics; (2) establish the reference change value for significant glomerular filtration rate changes; (3) model disease progression; and (4) explore comparative cost-effectiveness of kidney disease monitoring strategies.

Design

A longitudinal, prospective study was designed to: (1) assess accuracy of glomerular filtration rate equations at baseline (n = 1167) and their ability to detect change over 3 years (n = 875); (2) model disease progression predictors in 278 individuals who received additional measurements; (3) quantify glomerular filtration rate variability components (n = 20); and (4) develop a measurement model analysis to compare different monitoring strategy costs (n = 875).

Setting

Primary, secondary and tertiary care.

Participants

Adults (≥ 18 years) with stage 3 chronic kidney disease.

Interventions

Estimated glomerular filtration rate using the Chronic Kidney Disease Epidemiology Collaboration and Modification of Diet in Renal Disease equations.

Main outcome measures

Measured glomerular filtration rate was the reference against which estimating equations were compared with accuracy being expressed as P30 (percentage of values within 30% of reference) and progression (variously defined) studied as sensitivity/specificity. A regression model of disease progression was developed and differences for risk factors estimated. Biological variation components were measured and the reference change value calculated. Comparative costs of monitoring with different estimating equations modelled over 10 years were calculated.

Results

Accuracy (P30) of all equations was ≥ 89.5%: the combined creatinine-cystatin equation (94.9%) was superior (p < 0.001) to other equations. Within each equation, no differences in P30 were seen across categories of age, gender, diabetes, albuminuria, body mass index, kidney function level and ethnicity. All equations showed poor (< 63%) sensitivity for detecting patients showing kidney function decline crossing clinically significant thresholds (e.g. a 25% decline in function). Consequently, the additional cost of monitoring kidney function annually using a cystatin C-based equation could not be justified (incremental cost per patient over 10 years = £43.32). Modelling data showed association between higher albuminuria and faster decline in measured and creatinine-estimated glomerular filtration rate. Reference change values for measured glomerular filtration rate (%, positive/negative) were 21.5/-17.7, with lower reference change values for estimated glomerular filtration rate.

Limitations

Recruitment of people from South Asian and African-Caribbean backgrounds was below the study target.

Future work

Prospective studies of the value of cystatin C as a risk marker in chronic kidney disease should be undertaken.

Conclusions

Inclusion of cystatin C in glomerular filtration rate-estimating equations marginally improved accuracy but not detection of disease progression. Our data do not support cystatin C use for monitoring of glomerular filtration rate in stage 3 chronic kidney disease.

Trial registration

This trial is registered as ISRCTN42955626.

Funding

This award was funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme (NIHR award ref: 11/103/01) and is published in full in Health Technology Assessment; Vol. 28, No. 35. See the NIHR Funding and Awards website for further award information.

Changes in estimated glomerular filtration rate in patients administered proton pump inhibitors: a single-center cohort study

Proton pump inhibitor (PPI) use may be associated with renal dysfunction. Renal dysfunction in PPI users requires evaluation of development and progression risks simultaneously, using estimated glomerular filtration rate (eGFR) slope, which indicates changes in eGFR per year. To the best of our knowledge, no studies have evaluated eGFR slope in PPI users. This study investigated the association between PPI use and renal dysfunction using eGFR slope. A single-center cohort study was conducted using the health records data at Hamamatsu University Hospital in Japan. Participants were defined as first users of acid-suppressing drugs (PPIs or Histamine H2 receptor antagonists (H2RAs)) from 2010 to 2021 and continuously prescribed for  ≥ 90 days. The H2RA group was used for the propensity-score matching (PSM) to the PPI group to minimize the effects of confounders. The eGFR slope was estimated using a linear mixed effects model. Participants were stratified by baseline eGFR and age, respectively, as subgroup analyses. A total of 4,649 acid-suppressing drug users met the inclusion criteria, including 950 taking H2RAs and 3,699 PPIs. After PSM, 911 patients were assigned to each group. The eGFR slopes of the PPI and H2RA users were -4.75 (95% CI: -6.29, -3.20) and -3.40 (-4.38, -2.42), respectively. The difference between the groups was not significant. Significant declines in eGFR were observed with PPIs with baseline eGFR ≥ 90 and age  < 65. PPI use for  ≥ 90 days may hasten eGFR decline compared to H2RA use, especially in patients with eGFR  ≥ 90 or age  < 65.

Long-Term Blood Pressure Reductions Following Catheter-Based Renal Denervation: A Systematic Review and Meta-Analysis

BACKGROUND

Renal denervation is a recognized adjunct therapy for hypertension with clinically significant blood pressure (BP)-lowering effects. Long-term follow-up data are critical to ascertain durability of the effect and safety. Aside from the 36-month follow-up data available from randomized control trials, recent cohort analyses extended follow-up out to 10 years. We sought to analyze study-level data and quantify the ambulatory BP reduction of renal denervation across contemporary randomized sham-controlled trials and available long-term follow-up data up to 10 years from observational studies.

METHODS

A systematic review was performed with data from 4 observational studies with follow-up out to 10 years and 2 randomized controlled trials meeting search and inclusion criteria with follow-up data out to 36 months. Study-level data were extracted and compared statistically.

RESULTS

In 2 contemporary randomized controlled trials with 36-month follow-up, an average sham-adjusted ambulatory systolic BP reduction of -12.7±4.5 mm Hg from baseline was observed (P=0.05). Likewise, a -14.8±3.4 mm Hg ambulatory systolic BP reduction was found across observational studies with a mean long-term follow-up of 7.7±2.8 years (range, 3.5-9.4 years; P=0.0051). The observed reduction in estimated glomerular filtration rate across the long-term follow-up was in line with the predicted age-related decline. Antihypertensive drug burden was similar at baseline and follow-up.

CONCLUSIONS

Renal denervation is associated with a significant and clinically meaningful reduction in ambulatory systolic BP in both contemporary randomized sham-controlled trials up to 36 months and observational cohort studies up to 10 years without adverse consequences on renal function.

Slope of the estimated glomerular filtration rate and its associated factors among individuals with chronic kidney disease in the general Japanese population

BACKGROUND

To suppress the incidence of end-stage kidney disease, we need to identify chronic kidney disease (CKD) patients with a high risk of rapid decline in the estimated glomerular filtration rate (eGFR). However, the current status of eGFR slope and its associated factors in the Japanese population have not been fully elucidated.

METHODS

Among examinees aged 40-70 years in the 2014 Specific Health Checkup conducted by the National Health Insurance in Kobe, Japan (n = 61,985), we prospectively observed 7291 examinees with CKD stage G3 from 2014 to 2018.

RESULTS

Until 2018, 4221 examinees continued to undergo annual SHCs for a total of five checkups per subject and had available records of all necessary data. The median eGFR change was -0.22 ml/min/1.73 m2/year. Only 9.2% of those subjects showed rapid eGFR decline (faster than -2.0 ml/min/1.73 m2/year). Logistic regression analysis identified diabetes, smoking habits, high urinary protein levels, older age, high systolic blood pressure, and low serum low-density lipoprotein cholesterol levels as independent predictors for rapid eGFR decline. Hemoglobin A1c levels did not contribute to the eGFR slope in CKD stage-G3 subjects with diabetes and proteinuria.

CONCLUSION

Most Japanese CKD stage-G3 subjects had a very slow decline in eGFR. A small proportion of CKD individuals who have a predictive factor of rapid eGFR decline should receive considerable attention from a nephrologist.

The Factors Influencing Chronic Kidney Disease Incidence: Database from the Korean National Health Insurance Sharing Service (NHISS)

Background: The global prevalence of chronic kidney disease (CKD) is increasing, with diabetes accounting for the highest proportion. We analyzed the influence of clinical factors on the incidence of CKD according to the renal function, primary focusing on patients with diabetes. Methods: We used the Sample Cohorts Database provided by the National Health Insurance Sharing Service (NHISS) in Korea. Participants aged ≥ 40 years who underwent a health checkup in 2009 were categorized into six groups based on their eGFR values (<60 mL/min, 60-89 mL/min, ≥90 mL/min) and the presence of diabetes. And all patients with CKD at 2009 screening were excluded. The participants were tracked from 2010 to 31 December 2019. The CKD incidence rate according to the eGFR values and the effect of the accompanying factors on CKD incidence were confirmed. Results: 148,089 people without CKD were analyzed. The CKD incidence rate was highest in those with eGFR < 60 mL/min with diabetes and lowest in those with eGFR ≥ 90 mL/min without diabetes. The CKD incidence rates were similar between the eGFR < 60 mL/min group without diabetes and the eGFR 60-89 mL/min group with diabetes. Compared to under 44 years of age, the hazard ratio of CKD incidence was 8 times higher in over 75 years of age. Men had a 1.7-fold higher risk of developing CKD than women. Current smoker, hypertension, dyslipidemia, myocardial infarction history, and atrial fibrillation and flutter increased the risk of CKD incidence. Age, diabetes, and baseline eGFR are important factors in the occurrence of CKD. As age increases, the risk of developing CKD in men increases compared to women. Conclusions: These results will be helpful in predicting risk groups for CKD and establishing strategies to lowering CKD incidence.

Age-related markers and predictors of diabetic kidney disease progression in type 2 diabetes patients: a retrospective cohort study

Background

Diabetic kidney disease (DKD) is characterized by reduced estimated glomerular filtration rate (eGFR) and albuminuria, which play a pivotal role in both diagnosing and determining the disease's progression. This study aimed to assess the trajectory of these markers concerning age in individuals with DKD and identify predictive factors for the decline in eGFR decline, variation in albuminuria, mortality, and progression to renal replacement therapy (RRT).

Design

This retrospective cohort encompassed patients with type 2 diabetes (T2D), divided into two age categories: <75 and ⩾75 years old.

Methods

Over a 3-year span, the study evaluated eGFR (CKD-EPI) and 24-h albuminuria. Univariate and multivariate analyses were employed to pinpoint factors associated with deteriorating renal function and mortality. Significance was set at p < 0.05, and Kaplan-Meier survival curves were constructed to illustrate renal and overall survival.

Results

The analysis comprised 304 patients. Comparable eGFR declines were evident in both age groups during the transition from the first to the second year and from the second to the third year. Nonetheless, a more pronounced rise in albuminuria was evident in the ⩾75 years group during the first to the second year. Multivariate analysis unveiled that systolic blood pressure (SBP) measurements in the first year positively forecasted eGFR decline. Age was associated with heightened albuminuria and mortality, while hospitalizations linked to cardiovascular causes robustly predicted mortality. Hospitalizations due to sepsis and cardiovascular reasons, coupled with first-year SBP measurements, served as predictive indicators for progression to RRT.

Conclusion

Both age groups experienced similar declines in eGFR, though the ⩾75 years group displayed a more significant increase in albuminuria during the first to the second year. Age, hospitalizations, and higher blood pressure levels were correlated with exacerbated renal function deterioration and/or elevated mortality in DKD. Timely intervention and tailored management strategies stand as critical components for enhancing outcomes among DKD patients.

Study of prevalence, clinical profile, and predictors of rapid progression in diabetic kidney disease

BACKGROUND

A significant proportion of diabetic kidney disease (DKD) experience a rapid decline in eGFR, leading to end-stage kidney disease (ESKD) within months. This single-centered retrospective cohort study aimed to assess the prevalence, clinical profile, and predictors for rapid progression in type 2 diabetes mellitus (T2DM) patients with DKD.

METHOD

Three hundred fifty-nine T2DM patients with DKD between January 2018 and 2022 were included and those with superimposed non-diabetic kidney disease, chronic kidney disease 5, and < 6 months follow-up were excluded. They were classified as rapid and non-rapid progressors based on the annual eGFR decline of > 5 ml/min/1.73 m2/year. The primary outcome analyzed was the progression to ESKD. The secondary outcomes were the onset of microvascular and macrovascular complications and predictors for rapid progression as well as ESKD.

RESULTS

In a median follow-up of 3.5 years, 61.3% were rapid progressors (mean eGFR decline of 15.4 ml/1.73m2/year) and 38.7% were non-rapid progressors (mean eGFR decline 1.8 ml/1.73m2/year. Among rapid progressors, 61.4% reached ESKD. Severe proteinuria, the presence of retinopathy, and acute kidney injury (AKI) episodes were strong predictors of rapid progression. Cardiovascular disease and diabetic retinopathy (microvascular complications) were significantly higher among rapid progressors and had a mortality rate of 7.2%.

CONCLUSION

The majority of type 2 DKD patients were rapid progressors and two-thirds of them developed ESKD. The prevalence of hypertension, cardiovascular disease, diabetic retinopathy, AKI episodes, and mortality was higher in rapid progressors. Severe proteinuria and diabetic retinopathy were found to be strong predictors for rapid eGFR decline and its progression to ESKD.

Relationship of Frailty with Kidney Function in Adults More Than 60-Years-Old: Effect of Using Different Formulas to Estimate Glomerular Filtration Rate

Objective

Determine the relationship of renal function with frailty using different formulas for estimated glomerular filtration rate (eGFR).

Methods

Individuals who were 60-years-old or more (n=507) were recruited from August 2020 to June 2021, and the FRAIL scale was used to classify them as non-frail or frail. The three equations used to compute the eGFR were based on serum creatinine (eGFRcr), cystatin C (eGFRcys), or SCr+CysC (eGFRcr-cys). Renal function was classified using eGFR and defined as normal (≥90 mL/min/1.73m²), mild damage (59-89 mL/min/1.73m²), or moderate damage (≤60 mL/min/1.73m²). The relationship of frailty with renal function was analyzed. A subset of participants (n=358) was used to analyze changes in eGFR from 1 January 2012 to 31 December 2021 according to frailty and using the different eGFR equations.

Results

There were significant differences between the eGFRcr-cys and eGFRcr values in the frail group (P<0.05), but not the non-frail group; however, the differences between the eGFRcr-cys and eGFRcys values were significant in the frail and non-frail groups (P<0.001). Based on each eGFR equation, the prevalence of frailty increased as eGFR decreased (P<0.001), but there was no significant relationship after adjusting for age or the age-adjusted Charlson co-morbidity index. There were temporal declines in eGFR in all three frailty groups (robust, pre-frail, and frail), especially in the frail group (2.226 mL/min/1.73m² per year; P<0.001).

Conclusion

For older individuals who are frail, the eGFRcr value may not provide accurate estimates of renal function. Frailty is associated with a rapid decline in kidney function.

Visceral fat and attribute-based medicine in chronic kidney disease

Visceral adipose tissue plays a central role in obesity and metabolic syndrome and is an independent risk factor for both cardiovascular and metabolic disorders. Increased visceral adipose tissue promotes adipokine dysregulation and insulin resistance, leading to several health issues, including systemic inflammation, oxidative stress, and activation of the renin-angiotensin-aldosterone system. Moreover, an increase in adipose tissue directly and indirectly affects the kidneys by increasing renal sodium reabsorption, causing glomerular hyperfiltration and hypertrophy, which leads to increased proteinuria and kidney fibrosis/dysfunction. Although the interest in the adverse effects of obesity on renal diseases has grown exponentially in recent years, the relationship between obesity and renal prognosis remains controversial. This may be attributed to the long clinical course of obesity, numerous obesity-related metabolic complications, and patients' attributes. Multiple individual attributes influencing the pathophysiology of fat accumulation make it difficult to understand obesity. In such cases, it may be effective to elucidate the pathophysiology by conducting research tailored to individual attributes from the perspective of attribute-based medicine/personalized medicine. We consider the appropriate use of clinical indicators necessary, according to attributes such as chronic kidney disease stage, level of visceral adipose tissue accumulation, age, and sex. Selecting treatments and clinical indicators based on individual attributes will allow for advancements in the clinical management of patients with obesity and chronic kidney disease. In the clinical setting of obesity-related nephropathy, it is first necessary to accumulate attribute-based studies resulting from the accurate evaluation of visceral fat accumulation to establish evidence for promoting personalized medicine.

Kidney-Function Trajectories From Young Adulthood to Midlife: Identifying Risk Strata and Opportunities for Intervention

Introduction

Understanding normative patterns of change in kidney function over the life course may allow targeting of early interventions to slow or prevent the onset of kidney disease, but knowledge about kidney functional change before middle age is limited. This study used prospective longitudinal data from a representative birth cohort to examine common patterns of change from young to midadulthood and to identify risk factors and outcomes associated with poorer trajectories.

Methods

We used group-based trajectory modeling in the Dunedin study birth cohort (n = 857) to identify the following: (i) common kidney function trajectories between the ages 32 and 45 years, (ii) early-life factors associated with those trajectories, (iii) modifiable physical and psychosocial factors across adulthood associated with differences in trajectory slope, and (iv) links between trajectories and kidney-related outcomes at age 45 years.

Results

Three trajectory groups were identified and could be differentiated by age 32 years as follows: normal (58% of participants), low-normal (36%), and high-risk (6%) groups. Those from low socioeconomic backgrounds had higher odds of following a high-risk (vs. normal) trajectory. Modifiable factors (blood pressure, body mass index, inflammation, glycated hemoglobin, smoking, and socioeconomic status) across adulthood were associated with steeper age-related declines in kidney function, particularly among those in the low-normal and high-risk groups. Those in the low-normal and high-risk groups also had more adverse kidney-related outcomes at age 45 years.

Conclusion

The current findings could be used to inform the development of early interventions and point to socioeconomic conditions across the life course and health-related risk factors and behaviors in adulthood as kidney health promotion targets.

Pharmaceutical care program for patients with chronic kidney disease in the community pharmacy: Detection of nephrotoxic drugs and dose adjustment. Viability study

INTRODUCTION

Chronic kidney disease (CKD) is a major health problem. Early detection is the key to reducing morbidity and mortality, but it is difficult because it occurs without symptoms. Diagnosis of CKD is also important to avoid nephrotoxic drugs and to adjust the doses of other medications that may be affected. Pharmacies, due to their proximity to the population, frequency of patient visits, and knowledge of medication use are an ideal location for point-of-care diagnosis or CKD.

OBJECTIVE

To detect and refer to the primary care physician patients with low estimated glomerular filtration rate (eGFR) who use nephrotoxic drugs or who may require a dose adjustment.

METHODOLOGY

Pharmacy users over 60 years of age who agreed to participate were given a creatinine/eGFR test with a point-of-care meter. The eGFR was calculated and if it was less than 60 ml/min/1.73 m2, their medications were evaluated to identify nephrotoxic drugs or drugs that potentially required adjustment. If either were found, they were referred to their doctor for further management.

RESULTS

198 patients were recruited in 4 pharmacies, of which 87 (43.9%) had an eGFR less than 60 ml/min/1.73 m2. They were taking a total of 635 medications. Of these 635 medications, 50 (7.9%) were affected by kidney function. Dose adjustment was recommended in 31 and discontinuation in 19. The primary care doctor accepted the recommendations for 14 medications: dose adjustment for 6 and withdrawal in 8. This represents 2.3% of medications taken by patients with an eGFR less than 60 ml/min/1.73 m2. The 50 medications identified were taken by 29 patients (33.3% of the 87 with a low eGFR) and a change in treatment was generated in 9 patients, representing 4.6% of the total number of patients in the sample, and 10% of the patients with a low eGFR.

CONCLUSION

Point-of-care testing for kidney function in a pharmacy setting is feasible and identifies a significant number of patients with eGFR under 60 ml/min/1.73 m2. It also allows for appropriate medication management recommendations in this patient group.

Renal Function, Adherence and Quality of Life Improvement After Conversion From Immediate to Prolonged-Release Tacrolimus in Liver Transplantation: Prospective Ten-Year Follow-Up Study

Immunosuppression non-adherence is a major cause of graft failure after liver transplantation. The aim of this study was to evaluate practice surrounding conversion from immediate-release to prolonged-release Tacrolimus formulation and to assess patient adherence and quality of life (QoL). One hundred and seven adult liver transplant recipients, receiving immediate-release Tacrolimus for a minimum of 6 months, were converted to prolonged-release formulation, based on a dose ratio of one (1:1). The median follow-up was 120 [IQR, 120-123] months. Tacrolimus dosage and blood level, liver and renal function, lipid and glucose profiles were recorded. In addition, questionnaires were submitted to evaluate adherence and QoL following conversion. No rejection was recorded. The median serum Tacrolimus blood level decreased over 1 month (5.80, [IQR, 2.0-10.8] vs. 3.8 [IQR, 1.4-8.7]; p < 0.0005). Significant improvement in renal function was noted (median GFR was 81.7 [IQR, 43.4-128.6] vs. 73.9 [IQR, 27.1-130.2]; p = 0.0002). At the end of the follow-up, conversion resulted in an overall decrease in non-adherence of 53.3% (p = 0.0001) and an improvement in QoL was reported by 76.2% of patients. Thus, 1:1 conversion from immediate to prolonged-release Tacrolimus is safe, feasible and efficient, avoiding under-therapeutic and toxic peak concentrations, improving renal function, adherence to immunosuppression and overall patient QoL.

Structural and Functional Changes in Aging Kidneys

The renal condition is one of the crucial predictors of longevity; therefore, early diagnosis of any dysfunction plays an important role. Kidneys are highly susceptible to the aging process. Unfavorable conditions may lead to a significant disturbance of the body's homeostasis. Apart from physiological changes, there are some conditions such as hypertension, diabetes or obesity which contribute to the acceleration of the aging process. A determination of macroscopic and microscopic changes is essential for assessing the progression of aging. With age, we observe a decrease in the volume of renal parenchyma and an increase in adipose tissue in the renal sinuses. Senescence may also be manifested by the roughness of the kidney surface or simple renal cysts. The main microscopic changes are a thickening of the glomerular basement membrane, nephrosclerosis, an accumulation of extracellular matrix, and mesangial widening. The principal aspect of stopping unfavorable changes is to maintain health. Studies have shown many useful ways to mitigate renal aging. This review is focused especially on medications such as renin-angiotensin-aldosterone system blockers or resveratrol, but even eating habits and lifestyle.

Aging and hypertension in kidney function decline: A 10 year population-based study

Background

Aging is associated with a physiological decline in kidney function (KFD). In this study, we aimed to describe the impact of age on the rate of KFD and its interplay with risk factors for chronic kidney disease (CKD), considering mainly hypertension (HT), in the general population.

Materials and methods

Participants of European descent, aged 35-75, were recruited from a populational cohort in Lausanne, Switzerland. Participants with a 10 year follow-up were selected. KFD was defined as the difference in estimated glomerular filtration rate (eGFR) between baseline and follow-up, divided by the observation period. Multivariate linear regressions were used with KFD as the outcome and age as the main predictor. HT was tested as a modifying factor.

Results

We included 4,163 participants with mean age 52.2 ± 10.4, 44.7% men, 31.9% HT, and 5.0% diabetics. Mean baseline eGFR was 85.9 ± 14.6 ml/min/1.73 m². Mean KFD was -0.49 ± 1.08 ml/min/1.73 m² per year with 70% of participants decreasing their eGFR during follow-up. The relationship between age and KFD was non-linear and age was divided in tertiles. Old participants had faster rates of KFD as compared to young and middle-age participants (p < 0.001). A significant interaction was found between age and HT on KFD prediction (p < 0.001). In HT participants, KFD was significantly different across tertiles of age (p < 0.001). On contrary, KFD was not different across tertiles of age in non-HT participants.

Conclusion

A physiological KFD is present over time in the general population. Age contributes non-linearly to the rate of this decline with older subjects declining the fastest. The presence of HT is a major contributing factor in this setting as KFD worsened with age only in hypertensive participants. Thus, HT represents an important pathological factor aggravating the age-related physiological decline in eGFR in the general population.

Sex Differences in Age-Related Loss of Kidney Function

BACKGROUND

CKD is more prevalent in women, but more men receive kidney replacement therapy for kidney failure. This apparent contradiction is not well understood.

METHODS

We investigated sex differences in the loss of kidney function and whether any sex disparities could be explained by comorbidity or CKD risk factors. In the Renal Iohexol Clearance Survey (RENIS) in northern Europe, we recruited 1837 persons (53% women, aged 50-62 years) representative of the general population and without self-reported diabetes, CKD, or cardiovascular disease. Participants' GFR was measured by plasma iohexol clearance in 2007-2009 (n=1627), 2013-2015 (n=1324), and 2018-2020 (n=1384). At each study visit, healthy persons were defined as having no major chronic diseases or risk factors for CKD. We used generalized additive mixed models to assess age- and sex-specific GFR decline rates.

RESULTS

Women had a lower GFR than men at baseline (mean [SD], 90.0 [14.0] versus 98.0 [13.7] ml/min per 1.73 m2; P<0.001). The mean GFR change rate was -0.96 (95% confidence interval [CI], -0.88 to -1.04) ml/min per 1.73 m2 per year in women and -1.20 (95% confidence interval [CI], -1.12 to -1.28) in men. Although the relationship between age and GFR was very close to linear in women, it was curvilinear in men, with steeper GFR slopes at older ages (nonlinear effect; P<0.001). Healthy persons had a slower GFR decline, but health status did not explain the sex difference in the GFR decline.

CONCLUSION

Among middle-aged and elderly individuals in the general population, decline in the mean GFR in women was slower than in men, independent of health status.

Genetic loci and prioritization of genes for kidney function decline derived from a meta-analysis of 62 longitudinal genome-wide association studies

Estimated glomerular filtration rate (eGFR) reflects kidney function. Progressive eGFR-decline can lead to kidney failure, necessitating dialysis or transplantation. Hundreds of loci from genome-wide association studies (GWAS) for eGFR help explain population cross section variability. Since the contribution of these or other loci to eGFR-decline remains largely unknown, we derived GWAS for annual eGFR-decline and meta-analyzed 62 longitudinal studies with eGFR assessed twice over time in all 343,339 individuals and in high-risk groups. We also explored different covariate adjustment. Twelve genome-wide significant independent variants for eGFR-decline unadjusted or adjusted for eGFR-baseline (11 novel, one known for this phenotype), including nine variants robustly associated across models were identified. All loci for eGFR-decline were known for cross-sectional eGFR and thus distinguished a subgroup of eGFR loci. Seven of the nine variants showed variant-by-age interaction on eGFR cross section (further about 350,000 individuals), which linked genetic associations for eGFR-decline with age-dependency of genetic cross-section associations. Clinically important were two to four-fold greater genetic effects on eGFR-decline in high-risk subgroups. Five variants associated also with chronic kidney disease progression mapped to genes with functional in-silico evidence (UMOD, SPATA7, GALNTL5, TPPP). An unfavorable versus favorable nine-variant genetic profile showed increased risk odds ratios of 1.35 for kidney failure (95% confidence intervals 1.03-1.77) and 1.27 for acute kidney injury (95% confidence intervals 1.08-1.50) in over 2000 cases each, with matched controls). Thus, we provide a large data resource, genetic loci, and prioritized genes for kidney function decline, which help inform drug development pipelines revealing important insights into the age-dependency of kidney function genetics.

Age and the Course of GFR in Persons Aged 70 and Above

BACKGROUND AND OBJECTIVES

In older adults, data on the age-related course of GFR are scarce, which might lead to misjudgment of the clinical relevance of reduced GFR in old age.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

To describe the course of eGFR in older adults and derive reference values in population-based individuals, we used the longitudinal design of the Berlin Initiative Study (BIS) with a repeated estimation of GFR over a median of 6.1 years of follow-up. In 2069 community-dwelling older individuals (mean inclusion age 80 years, range 70-99), GFR was estimated biennially with the BIS-2 equation, including standardized creatinine and cystatin C levels, sex, and age. We described the crude and adjusted course using a mixed-effects model and analyzed the influence of death on the GFR course applying joint models. GFR slopes were compared using GFR equations on the basis of creatinine and/or cystatin C.

RESULTS

We observed a decreasing, thus nonlinear, eGFR decline with increasing age in a population of old adults. The estimated 1-year slope for ages 75 and 90 diminished for men from -1.67 to -0.99 and for women from -1.52 to -0.97. The modeled mean eGFR for men aged ≥79 and women ≥78 was below 60 ml/min per 1.73 m². Multivariable adjustment attenuated slopes only minimally. Taking death into account by applying joint models did not alter the nonlinear eGFR decline. Using eGFR equations on the basis of creatinine only showed linear slope patterns in contrast to nonlinear patterns for equations including cystatin C.

CONCLUSIONS

The eGFR decline depended on sex and age and changed only marginally after multivariable adjustment but decelerated with increasing age. Equations including cystatin C demonstrated a nonlinear slope challenging the previously assumed linearity of the decline of eGFR in old age.

Newly initiated cardiovascular medication and short-term risk of unintentional poisoning among Swedish middle-aged and older adults: A national register-based case-crossover study

BACKGROUND

Although some studies have shown the average side effects of cardiovascular medication, the short-term effect after newly initiated cardiovascular medications has not been studied in any detail. We aim to determine the effect of newly initiated cardiovascular medications resulting in unintentional poisoning and to identify those at high risk.

METHODS

A case-crossover design was used. From the Swedish National Patient Register, a total of 9,354 persons aged ≥ 50 and hospitalized with a first event of unintentional poisoning between July 2006 and September 2018 were identified. Through linkage to the Prescribed Drug Register, exposure to newly initiated cardiovascular medication during the case period (1-28 days prior to the onset date of unintentional poisoning) was compared with that in a corresponding control period (113-140 days prior to the onset date). Conditional logistic regression was used to determine the associations in total, for different time periods as well as by age, sex, underlying comorbidity, and use of other medications.

RESULTS

Newly initiated cardiovascular medications were associated with a higher risk of unintentional poisoning, especially during the first week after initiation (odds ratio [OR]=1.39), (95% confidence interval [CI]=1.08-1.79). The risk of unintentional poisoning was comparable across age groups, sex, underlying comorbidities, and medications with OR (95% CI) ranging from 1.15 (0.75-1.74) to 2.00 (1.15-3.47).

CONCLUSION

This large population-based case-crossover study showed that newly initiated cardiovascular medication is associated with an increased risk of unintentional poisoning, particularly during the first week after initiation. The risk is comparable across age, sex, underlying comorbidity, and medications.

Efficacy and safety of Zicuiyin decoction on diabetic kidney disease: A multicenter, randomized controlled trial

BACKGROUD

Zicuiyin (ZCY) decoction created by Xichun Zhang in the Qing dynasty has been used on diabetes mellitus and complications for more than two centuries in China. Huangkui capsule (HKC) is a listed Chinese patent medicine to treat diabetic kidney disease (DKD). To determine whether ZCY is non-inferior to HKC in the treatment of DKD, a multicenter, parallel-control, open-label, randomized clinical trial was conducted.

METHODS

In this clinical trial, 88 DKD patients were recruited at three centers in Tianjin from January 2018 to December 2019. They were randomized to receive HKC (2.5 g, TID) or ZCY (crude drug amount 75 g, 150 ml, BID) for eight weeks based on routine treatment. The primary outcome was the change of estimated glomerular filtration rate (eGFR). The secondary outcomes included change of serum creatinine (SCr), urinary albumin excretion rate, 24 h urinary protein, urinary albumin-creatinine ratio, glycosylated hemoglobin A1c, symptom scores, and microbiota compositions profiles.

RESULTS

The change of eGFR in HKC and ZCY groups were -7.08 ± 24.65 and 2.57 ± 18.49 ml/min/1.73 m², respectively (p < 0.05). The 95% lower confidence limit for the difference between the estimated means was 1.93 ml/min/1.73 m², establishing the superiority of ZCY. Compared to HKC, ZCY could significantly decrease SCr and symptom scores (p < 0.05). There were no significant differences in other outcomes between the two groups (p > 0.05). ZCY ameliorated gut microbiota dysbiosis, including increased Prevotellaceae and Lactobacillaceae and decreased Enterobacteriales, Clostridiaceae and Micrococcaceae. No severe adverse events were reported in any group.

CONCLUSIONS

ZCY had better efficacy in improving and protecting kidney function. It would be an alternative option to treat DKD, especially those who decline eGFR and gut microbiota dysbiosis.

TRIAL REGISTRATION

Chinese Clinical Trial Registry: ChiCTR-OON-17012076. Registered July 21, 2017.

Factors Associated with Symptom Burden in Adults with Chronic Kidney Disease Undergoing Hemodialysis: A Prospective Study

People with end stage renal disease and undergoing hemodialysis experience a high symptom burden that impairs quality of life. This study aimed to assess the prevalence, dynamicity and determinants of symptom burden among middle-aged and older adult hemodialysis patients. A descriptive cross-sectional study together with a longitudinal assessment was used. A total of 118 and 102 hemodialysis patients were assessed at baseline and at a 6-month follow-up. Validated questionnaires were used to assess the symptom burden, stress, illness perception and social support. Multiple linear regression analysis was used to determine the factors associated with symptom burden. The median number of symptoms experienced was 21 (Interquartile Range (IQR); 18−23) and 19 (IQR; 13−22) at baseline and 6 months, respectively. Having elevated stress (β = 0.65, p ≤ 0.005) and illness perception (β = 0.21, p = 0.02) were significantly predicted symptom burden at baseline (F (4, 112) = 55.29, p < 0.005, R2 = 0.664). Stress (β = 0.28, p = 0.003), illness perception (β = 0.2, p = 0.03), poor social support (β = −0.22, p = 0.01) and low body weight (β = −0.19, p = 0.03) were the determinants for symptom burden at 6 months (F (5, 93) = 4.85, p ≤ 0.005, R2 = 0.24). Elevated stress, illness perception level, poor social support and low post-dialysis body weight were found to be determinants for symptom burden. Attention should be given to psychosocial factors of hemodialysis patients while conducting assessment and delivering care to patients.

Hemoglobin glycation index predicts renal function deterioration in patients with type 2 diabetes and a low risk of chronic kidney disease

AIMS

Hemoglobin glycation index (HGI) is used to describe the difference between estimated and measured glycated hemoglobin (HbA_1c). We aimed to study whether HGI can predict renal function deterioration in patients with type 2 diabetes and a low risk of chronic kidney disease (CKD).

METHODS

This retrospective cohort study enrolled 780 patients with type 2 diabetes and a low CKD risk according to the criteria of kidney disease: improving global outcomes. Participants were divided into two subgroups according to the baseline HGI calculated by fasting blood glucose and HbA_1c. Multivariate Cox proportional hazard models were used to evaluate the hazard ratios of the study endpoints. Longitudinal data was analyzed using generalized estimating equation (GEE).

RESULTS

The participants were followed for a median of 7.3 years. A high HGI predicted rapid renal function decline without or with a resultant eGFR < 60 ml/min/1.73 m², but not onset of macroalbuminuria. The longitudinal GEE model demonstrated a negative association between HGI and the predicted eGFR changes in both the 1-year and 3-year intervals.

CONCLUSIONS

HGI independently predicted renal function deterioration in patients with type 2 diabetes and a low CKD risk. Further investigations are warranted to elucidate its potential clinical impact.

Development and Validation of a Prediction Model for 5-Year Risk of Kidney Dysfunction in Patients with Hypertension and Glucose Metabolism Disorder

Purpose

Patients with hypertension and glucose metabolism disorder (GMD) are at high risk of developing kidney dysfunction (KD). Therefore, we aimed to develop a nomogram for predicting individuals’ 5-year risk of KD in hypertensives with GMD.

Patients and Methods

In total, 1961 hypertensives with GMD were consecutively included. Baseline data were extracted from medical electronic system, and follow-up data were obtained using annual health check-ups or hospital readmission. KD was defined as estimated glomerular filtration rate (eGFR) <60 mL/min/1.73m². Subjects were randomly divided into training and validation sets with a ratio of 7 to 3. Least absolute shrinkage and selection operator method was used to identify potential predictors. Cox proportional hazard model was applied to build a nomogram for predicting KD risk. The discriminative ability, calibration and usefulness of the model were evaluated. The prediction model was verified by internal validation.

Results

During the follow-up of 5351 person-years with a median follow-up of 32 (range: 3–91) months, 130 patients developed KD. Age, sex, ethnicity, hemoglobin A1c, uric acid, and baseline eGFR were identified as significant predictors for incident KD and used for establishing nomogram. The prediction model displayed good discrimination with C-index of 0.770 (95% CI: 0.712–0.828) and 0.763 (95% CI: 0.704–0.823) in training and validation sets, respectively. Calibration curve indicated good agreement between the predicted and actual probabilities. The decision curve analysis demonstrated that the model was clinically useful.

Conclusion

The prediction nomogram, including six common easy-to-obtain factors, shows good performance for predicting 5-year risk of KD in hypertensives with GMD. This quantitative tool could help clinicians, and even primary care providers, recognize potential KD patients early and make strategy for prevention and management.

Determinants of the Evolution of Kidney Function With Age

Introduction

Kidney function declines with age, but its determinants in the general population remain incompletely understood. We investigated the rate and determinants of kidney function decline in the general population.

Methods

Participants with information on kidney function were selected from a population-based cohort study. Joint models were used to investigate the evolution of the estimated glomerular filtration rate (eGFR, expressed in ml/min per 1.73 m² per year) and the urine albumin-to-creatinine ratio (ACR, expressed in mg/g per year) with age. We stratified for 8 potential determinants of kidney function decline, including sex, cardiovascular risk factors, and cardiovascular disease.

Results

We included 12,062 participants with 85,922 eGFR assessments (mean age 67.0 years, 58.7% women) and 3522 participants with 5995 ACR measurements. The annual eGFR decline was 0.82 and the ACR increase was 0.05. All determinants appeared detrimental for eGFR and ACR, except for prediabetes and higher body mass index which proved only detrimental for ACR. In participants without the determinants, eGFR decline was 0.75 and ACR increase was 0.002. Higher baseline eGFR but faster eGFR decline with age was detected in men (0.92 vs. 0.75), smokers (0.90 vs. 0.75), and participants with diabetes (1.07 vs. 0.78).

Conclusion

We identify prediabetes, smoking, and blood pressure as modifiable risk factors for kidney function decline. As with diabetes, hyperfiltration seems important in accelerated kidney function decline in men and smokers. The interpretation of kidney function decline may require adjustment for age and sex to prevent overdiagnosis of chronic kidney disease in aging populations.

Association between metabolic syndrome components and chronic kidney disease among 37,533 old Chinese individuals

Background

Chronic kidney disease (CKD) has become a worldwide health problem among aging populations. However, epidemiological information on Chinese elderly people with CKD is still lacking. This study aimed to investigate the epidemiological features and associated risk factors of CKD in aging population in China.

Methods

In this cross-sectional study, a total of 37,533 individuals aged ≥ 65 years were enrolled in Binhai from January to December 2018. The crude and standardized prevalence of CKD were calculated. Associations of metabolism-related indicators with CKD were examined using univariate and multivariate analyses.

Results

The overall prevalence of CKD was 17.7% (95% confidence interval 17.3–18.1%) in this Chinese elderly population. The prevalence was 17.5% among men (95% CI 17.0–18.1%) and 17.8% among women (95% CI 17.3–18.4%). The mean eGFR was 84.22 (SD ± 12.87) mL/min/1.73 m², with the median value higher for women than for men.

Conclusion

Our study shows a high prevalence of CKD among Chinese elderly population. Aging, pre-HTN, HTN, elevated triglyceride, and FBG were associated with the risk of CKD. More attention should be paid to metabolic diseases to prevent CKD in the elderly.

Renal function decline in older men and women with advanced chronic kidney disease-results from the EQUAL study

INTRODUCTION

Understanding the mechanisms underlying the differences in renal decline between men and women may improve sex-specific clinical monitoring and management. To this end, we aimed to compare the slope of renal function decline in older men and women in chronic kidney disease (CKD) Stages 4 and 5, taking into account informative censoring related to the sex-specific risks of mortality and dialysis initiation.

METHODS

The European QUALity Study on treatment in advanced CKD (EQUAL) study is an observational prospective cohort study in Stages 4 and 5 CKD patients ≥65 years not on dialysis. Data on clinical and demographic patient characteristics were collected between April 2012 and December 2018. Estimated glomerular filtration rate (eGFR) was calculated using the CKD Epidemiology Collaboration equation. eGFR trajectory by sex was modelled using linear mixed models, and joint models were applied to deal with informative censoring.

RESULTS

We included 7801 eGFR measurements in 1682 patients over a total of 2911 years of follow-up. Renal function declined by 14.0% [95% confidence interval (CI) 12.9-15.1%] on average each year. Renal function declined faster in men (16.2%/year, 95% CI 15.9-17.1%) compared with women (9.6%/year, 95% CI 6.3-12.1%), which remained largely unchanged after accounting for various mediators and for informative censoring due to mortality and dialysis initiation. Diabetes was identified as an important determinant of renal decline specifically in women.

CONCLUSION

In conclusion, renal function declines faster in men compared with women, which remained similar after adjustment for mediators and despite a higher risk of informative censoring in men. We demonstrate a disproportional negative impact of diabetes specifically in women.

Brahma-related gene-1 promotes tubular senescence and renal fibrosis through Wnt/β-catenin/autophagy axis

Although accelerated cellular senescence is closely related to the progression of chronic kidney disease (CKD) and renal fibrosis, the underlying mechanisms remain largely unknown. Here, we reported that tubular aberrant expression of Brahma-related gene 1 (BRG1), an enzymatic subunit of the SWItch/Sucrose Non-Fermentable complex, is critically involved in tubular senescence and renal fibrosis. BRG1 was significantly up-regulated in the kidneys, predominantly in tubular epithelial cells, of both CKD patients and unilateral ureteral obstruction (UUO) mice. In vivo, shRNA-mediated knockdown of BRG1 significantly ameliorated renal fibrosis, improved tubular senescence, and inhibited UUO-induced activation of Wnt/β-catenin pathway. In mouse renal tubular epithelial cells (mTECs) and primary renal tubular cells, inhibition of BRG1 diminished transforming growth factor-β1 (TGF-β1)-induced cellular senescence and fibrotic responses. Correspondingly, ectopic expression of BRG1 in mTECs or normal kidneys increased p16INK4a, p19ARF, and p21 expression and senescence-associated β-galactosidase (SA-β-gal) activity, indicating accelerated tubular senescence. Additionally, BRG1-mediated pro-fibrotic responses were largely abolished by small interfering RNA (siRNA)-mediated p16INK4a silencing in vitro or continuous senolytic treatment with ABT-263 in vivo. Moreover, BRG1 activated the Wnt/β-catenin pathway, which further inhibited autophagy. Pharmacologic inhibition of the Wnt/β-catenin pathway (ICG-001) or rapamycin (RAPA)-mediated activation of autophagy effectively blocked BRG1-induced tubular senescence and fibrotic responses, while bafilomycin A1 (Baf A1)-mediated inhibition of autophagy abolished the effects of ICG-001. Further, BRG1 altered the secretome of senescent tubular cells, which promoted proliferation and activation of fibroblasts. Taken together, our results indicate that BRG1 induces tubular senescence by inhibiting autophagy via the Wnt/β-catenin pathway, which ultimately contributes to the development of renal fibrosis.

A Spectrum of Biopsy - Proven Renal Disorders and Their Clinicopathological Correlation in Elderly Population From a Tertiary Care Center in South India

Introduction

Chronic kidney disease (CKD) has become a health concern with an extensive burden on incidence and prognosis. While the increasing lifespan contributes to a higher incidence of CKD among the elderly, the diagnostic picture in this age group is complicated by senescence-related changes. A better understanding of the etiology and progression of the disease warrants renal biopsy in such patients. This study aims to explore the histopathological spectrum of native renal biopsies leading to CKD in elderly patients in a tertiary care hospital.

Methods

Among the list of patients who had undergone renal biopsy at our institute from January 2015 to March 2020, elderly patients aged ≥ 60years were chosen for this study. Their demographic details, lab investigations and histopathological reports were collected. The sex distribution and prevalence of different renal diseases was calculated. The subjects were classified into four broad diagnostic groups - primary glomerular disease, diabetic nephropathy, hypertensive nephropathy, and tubulointerstitial disease. The estimated glomerular filtration rate (eGFR) values were calculated and used to stage chronic kidney disease in these patients. Statistical analysis was carried out to find a correlation between diagnostic groups and CKD presence and between serum C3 values and immunofluorescence for the same on biopsy.

Results

One hundred thirty-two patients formed the study sample with a male to female ratio of 1.28:1, showing a slight male predominance. The most common diagnostic group was primary glomerular disease (46%), among which focal segmental glomerulosclerosis (FSGS) was the most common entity (12%). 47.7% and 66.6% of patients in the study sample showed elevated serum blood urea nitrogen (BUN) and creatinine values, respectively. 86% of our study sample had low eGFR values, and the majority (35%) of the patients were classified under CKD stage 3. CKD incidence was high among patients with primary glomerular diseases, but no significant statistical correlation was found. 43.5% of all IF positive cases showed low serum C3 values and established a positive correlation between IF and serum C3 values.

Conclusion

There is no statistically significant correlation of the four diagnostic groups to the CKD. CKD in the elderly may be multifactorial, and a collaborative study across the nations may be needed to further evaluate the etiology.

Targeting an anchored phosphatase-deacetylase unit restores renal ciliary homeostasis

Pathophysiological defects in water homeostasis can lead to renal failure. Likewise, common genetic disorders associated with abnormal cytoskeletal dynamics in the kidney collecting ducts and perturbed calcium and cAMP signaling in the ciliary compartment contribute to chronic kidney failure. We show that collecting ducts in mice lacking the A-Kinase anchoring protein AKAP220 exhibit enhanced development of primary cilia. Mechanistic studies reveal that AKAP220-associated protein phosphatase 1 (PP1) mediates this phenotype by promoting changes in the stability of histone deacetylase 6 (HDAC6) with concomitant defects in actin dynamics. This proceeds through a previously unrecognized adaptor function for PP1 as all ciliogenesis and cytoskeletal phenotypes are recapitulated in mIMCD3 knock-in cells expressing a phosphatase-targeting defective AKAP220-ΔPP1 mutant. Pharmacological blocking of local HDAC6 activity alters cilia development and reduces cystogenesis in kidney-on-chip and organoid models. These findings identify the AKAP220-PPI-HDAC6 pathway as a key effector in primary cilia development.

The distribution of eGFR by age in a community-based healthy population: the Japan specific health checkups study (J-SHC study)

BACKGROUND

Renal function gradually declines with age. However, the association between changes in renal function and healthy aging has not been determined. This study examined the distribution of estimated glomerular filtration rate (eGFR) values in healthy subjects by age using large-scale cross-sectional data of health check-up participants in Japan.

METHODS

Among the 394,180 health check-up participants, 75,217 (19.1%) subjects without hypertension, diabetes, hyperlipidemia, obesity, proteinuria, smoking, past history of cardiovascular diseases, and renal failure/not undergoing dialysis were included in the healthy group. The distribution of eGFR values was determined at each age between 39 and 74 years.

RESULTS

in healthy subjects, the mean (± 2 SD range) values of eGFR (mL/min/1.73 m²) at ages 40, 50, 60, and 70 were 88.0 (55.4-121.7), 82.3 (51.2-113.3), 77.8 (48.1-107.6), and 72.9 (44.7-101.1), respectively. The difference in the mean eGFR by age was almost constant across all ages. In the linear regression analysis adjusted for sex, the regression coefficient of mean eGFR for a one-year increase in age was -0.46 mL/min/1.73 m² in healthy subjects (P < 0.001). By sex, the distribution of eGFR and the 1-year change in eGFR showed similar results in both men and women.

CONCLUSIONS

Renal function slowly declined with age in a healthy population; however, it was relatively preserved until the mid 70 s. This result suggests that a decline in renal function often observed in the elderly does not attribute to aging alone, and further examination might be required to clarify the cause of renal impairment.

Different kidney function trajectory patterns before dialysis in elderly patients: clinical implications and outcomes

Background. Identifying trajectories of kidney disease progression in chronic kidney disease (CKD) patients may help to deliver better care. We aimed to identify and characterize trajectories of renal function decline in CKD patients and to investigate their association with mortality after dialysis.

Methods. This retrospective cohort study included 378 CKD patients who initiated dialysis (aged 65 years and over) between 2009 and 2016. Were considered mixed models using linear quadratic and cubic models to define the trajectories, and we used probabilistic clustering procedures. Patient characteristics and care practices at and before dialysis were examined by multivariable multinomial logistic regression. The association of these trajectories with mortality after dialysis was examined using Cox models.

Results. Four distinct groups of eGFR trajectories decline before dialysis were identified: slower decline (18.3%), gradual decline (18.3%), early rapid decline (41.2%), and rapid decline (22.2%). Patients with rapid eGFR decline were more likely to have diabetes, more cognitive impairment, to have been hospitalized before dialysis, and were less likely to have received pre-dialysis care compared to the patients with a slower decline. They had a higher risk of death within the first and fourth year after dialysis initiation, and after being more than 4 years in dialysis.

Conclusions. There are different patterns of eGFR trajectories before dialysis initiation in the elderly, that may help to identify those who are more likely to experience an accelerated decline in kidney function, with impact on pre ESKD care and in the mortality risk after dialysis.

Diabetic kidney disease in patients with type 2 diabetes mellitus: a cross-sectional study

Aim

Diabetic kidney disease (DKD) is a major long-term complication of diabetes mellitus (DM). Given the paucity of data on DKD in Jordan, we aimed to evaluate the prevalence, characteristics and correlates of DKD in Jordanian patients with type 2 DM.

Methods

This cross-sectional study included 1398 adult patients with type 2 DM who sought medical advice in the endocrinology clinic between March and September 2019. Demographic, clinical and laboratory data were reviewed. DKD was defined as reduced eGFR, and/or albuminuria. Three regression models were constructed to identify factors associated with CKD stages, albuminuria and DKD.

Results

Overall, 701 (50.14%) patients had DKD, with a median age of 59.71 ± 11.36  years. Older age, high triglycerides, and low high-density lipoprotein were associated with DKD (multivariable odds ratio [OR]: 1.02, 95% confidence interval [CI]: 1.01–1.03, p < 0.01; OR: 1.1, 95% CI: 1.01–1.2; and OR: 0.98, 95% CI: 0.97–0.99, p < 0.01 respectively). Metformin and renin-angiotensin system blockers were negatively associated with albuminuria and chronic kidney disease stages (p < 0.01).

Conclusion

Our study demonstrated that approximately one half of patients with type 2 DM had DKD. Further studies are necessary to understand this high prevalence and the underlying factors. Future research are needed to assess implementing targeted community-based intervention.

Nephrosclerosis impacts time trajectory of renal function and outcomes in elderly individuals with chronic kidney disease

Despite hypertension ranks among the leading causes of chronic kidney disease (CKD), the impact of chronic hypertensive nephropathy, the so-called 'nephrosclerosis' (NS), on CKD progression is often unpredictable, particularly in elderly population. We have conducted a prospective, observational study to define renal function patterns and outcomes in elderly CKD individuals with or without NS. Three hundred four individuals with an already established CKD were categorized according to the etiology of CKD. NS was defined as the presence of CKD associated with long-term essential hypertension, hypertensive retinopathy, left ventricular hypertrophy and minimal proteinuria. Time trajectories in estimated glomerular filtration rate (eGFR) (CKD-Epi) were computed over a 4-year follow-up. In addition, we analyzed the occurrence of a composite outcome of doubling of serum creatinine levels, eGFR reduction ≥25% and/or the need of chronic renal replacement therapy. CKD was secondary to nephrosclerosis (CKD-NS) in 220 (72.3%). In the whole cohort, the average estimated annual GFR slope was 1.8 mL/min/1.73 m² eGFR decline was slower in CKD-NS as compared with others (1.4 vs 3.4 mL/min/1.73 m²; p<0.001). The composite renal outcome during follow-up occurred less frequently among elderly with CKD-NS (16/204 vs 14/70; p=0.01, crude HR 0.43, 95% CI 0.22 to 0.85) and was associated at logistic analyses with the etiology of CKD, background cardiovascular disease, total and low density lipoproteins (LDL) cholesterol, and glycemia levels (p value was ranging from 0.01 to 0.05). Despite being highly prevalent in the elderly, NS is associated with a more favorable renal disease course as compared with other conditions.

Rapid decline in estimated glomerular filtration rate in sickle cell anemia: results of a multicenter pooled analysis

Not available.

Chronic kidney disease progression in aged patients

PURPOSE

Chronic kidney disease (CKD) is a major morbidity, and its prevalence increases with age. However, there appears to be some confusion about the prognosis of CKD in aged patients, because, it has its own characteristics different from youngers. In this study, we investigated the progression of CKD and related factors in aged patients.

METHODS

This was a retrospective study including 334 patients over 80 years of age that were diagnosed with stage 3-4 CKD at our CKD clinic. CKD progression was assessed as an annual decline in the estimated glomerular filtration rate (eGFR). Comorbidities were globally categorized with the Charlson comorbidity index (CCI), but diabetes mellitus, hypertension, and cardiac morbidities were evaluated separately. Patients were grouped as either 'progression to end-stage renal disease (ESRD)' or 'others'.

RESULTS

During the follow-up period, 191 (57.2%) patients exhibited progression; the annual median eGFR declined by 0.8 ml/min/1.73 m². Only 27 (8.1%) of these patients progressed to ESRD. In univariant and multivariate models, respectively, progressing to ESRD was significantly associated with cardiac comorbidities (p < 0.001, p < 0.001), proteinuria (p < 0.001, p = 0.03), and the baseline eGFR value (p < 0.001, p < 0.001).

CONCLUSION

In aged patients, CKD progressed slowly, but particularly high initial creatinine levels and proteinuria could be indicator of progression. In addition, cardiac comorbidities may facilitate progression to ESRD.

Bariatric Surgery Is Protective Against Renal Function Decline in Severely Obese Patients in the Long-Term

PURPOSE

This study aims to assess the long-term renal effects of bariatric surgery (BS) in severely obese patients over a follow-up period of up to 11 years.

MATERIALS AND METHODS

In a retrospective cohort study including 102 patients, patients were stratified by eGFR at baseline and divided into three groups: (1) reduced, (2) normal, and (3) increased filtration rate. Adjustments for age- and sex-related decline in eGFR were performed. We used uni- and multivariate regression analysis to identify variables that were thought to determine change in eGFR.

RESULTS

Over a median follow-up of 8.5 years (interquartile range 2.7), eGFR declined from 96.1 ± 20.7 to 84.9 ± 21.0 ml/min (p < 0.001). Among patients with (1), eGFR remained stable (69.1 ± 19.3 ml/min). Among patients with (2), eGFR declined from 99.7 ± 13.3 ml/min to 88.7 ± 19.4 ml/min (p < 0.001). Among patients with (3), eGFR decreased to normal levels (94.2 ± 17.7 ml/min, p < 0.001). Age- and sex-adjusted eGFR increased (6.4 ± 14.4 ml/min; p < 0.05) among patients with reduced filtration rate. Among patients with normal filtration rate, adjusted eGFR remained stable during follow-up (-1.3 ± 15.2 ml/min; n.s.). Among patients with increased filtration rate, adjusted eGFR decreased and remained within the normal range (-13.2 ± 12.2 ml/min; p < 0.001). Change in eGFR showed a negative correlation with eGFR at baseline (B = -0.31; p < 0.001), change in LDL-cholesterol (B = -0.09; p < 0.05), and a negative correlation with treatment requiring hypertension (B = -9.36; p = 0.001).

CONCLUSION

BS is protective against renal function decline in severely obese patients in the long term.

Frailty and the risk of kidney function decline in the elderly population: the Rugao Longevity and Ageing Study

BACKGROUND

The diverse risk factors for kidney impairments suggest that kidney function decline is more likely to occur in individuals with a broadly constituted health deficit. Here we conducted a longitudinal cohort study to evaluate the association of baseline frailty status with the risk of estimated glomerular filtration rate (eGFR) decline.

METHODS

Overall, 1269 participants aged 70-84 years from Rugao Longevity and Ageing cohort with 3-year follow-up were included. Frailty was measured using a modified Fried frailty assessment. GFR was estimated using the Chronic Kidney Disease Epidemiology Collaboration equation. Associations between baseline frailty status and rapid eGFR decline were examined by multinomial logistic analysis. A linear mixed-effect model was used to determine eGFR decline in mL/min/1.73 m2 over the study period comparing those with frail or prefrail at baseline versus those with robust status.

RESULTS

The mean (± standard deviation) age of participants was 75.1 ± 3.8 years. A total of 144 (11%) participants had rapid eGFR decline by at least 10% during the 3-year follow-up. Compared with robust status, baseline frail status was associated with a 2.48-fold [95% confidence interval (CI) 1.24-4.95] increased risk of rapid eGFR decline after multiple adjustments. In multivariate linear mixed model analysis, subjects with frail status but not prefrail status at baseline had a significant coefficient of -1.70 (95% CI -3.35 to -0.04) for the frail × visit term, which indicates an accelerated eGFR decline compared with robust subjects over the study period (P = 0.044).

CONCLUSIONS

Frailty may serve as an independent biomarker to predict the decline of kidney function.

Effectiveness of a locality-based integrated diabetes care service on clinical outcomes

AIMS

To evaluate the effectiveness of a new locality-based integrated diabetes care service for people with Type 2 diabetes in an inner regional area.

METHODS

A quasi-experimental evaluation comparing baseline and follow up clinical data collected from general practices and specialist services participating in an integrated diabetes care programme in an inner-regional area. Patients had at least one specialist service consultation. The primary outcome was glycated haemoglobin (HbA1c).

RESULTS

Clinical data were collected for 178/239 patients (74.5% participation; aged 65± 11(SD) years, 46% female; median [interquartile range (IQR)] diabetes duration 19 (11.0-24.0) years from seven general practices over 33 months (median 18.5 months). There were reductions in HbA1c -0.7±1.6 % (8±18 mmol/mol) (p<0.001), systolic blood pressure -5.8±19.5 mmHg (p<0.001), diastolic blood pressure -2.4±14.3 mmHg (p=0.04), total cholesterol -0.5±1.3 mmol/l (p<0.001), low-density lipoprotein (LDL) -0.4±0.9 mmol/l (p<0.001), Body Mass Index -0.5±1.6 kg/m² (p<0.001), weight -1.8±4.7 kg (p<0.001). Urine albumin creatinine ratio [median (IQR)] at baseline was 3.0 mg/mmol (0.7-7) vs follow up 1.9 mg/mmol (0.8-5.5) p< 0.54).

CONCLUSIONS

Glycaemia and cardiovascular risk factors can be reduced in patients with long-standing Type 2 diabetes by moving to a locality based integrated primary-secondary care diabetes care service. This article is protected by copyright. All rights reserved.

Age differences in the relationships between risk factors and loss of kidney function: a general population cohort study

BACKGROUND

Annual decline in kidney function is a widely applied surrogate outcome of renal failure. It is important to understand the relationships between known risk factors and the annual decline in estimated glomerular filtration rate (eGFR) according to baseline age; however, these remain unclear.

METHODS

A community-based retrospective cohort study of adults who underwent annual medical examinations between 1999 and 2013 was conducted. The participants were stratified into different age groups (40-49, 50-59, 60-69, 70-79, and ≥ 80 years) to assess the risk for loss of kidney function. A mixed-effects model was used to estimate the association between risk factors and annual changes in eGFR.

RESULTS

In total, 51,938 participants were included in the analysis. The age group of ≥80 years included 8127 individuals. The mean annual change in eGFR was - 0.39 (95% confidence interval: - 0.41 to - 0.37) mL/min/1.73 m² per year. Older age was related to faster loss of kidney function. In the older age group, higher systolic blood pressure, proteinuria, and current smoking were related to faster loss of kidney function (p trend < 0.01, 0.03, and < 0.01, respectively). Conversely, each age group showed similar annual loss of kidney function related to lower hemoglobin levels and diabetes mellitus (p trend 0.47 and 0.17, respectively).

CONCLUSIONS

Higher systolic blood pressure, proteinuria, and smoking were related to faster loss of kidney function, and a greater effect size was observed in the older participants. More risk assessments for older people are required for personalized care.

Fluid Intake Recommendation Considering the Physiological Adaptations of Adults Over 65 Years: A Critical Review

The aim of this critical review was to clarify recommended fluid intake for older people. A literature search of published articles and guidelines on fluid intake recommendations until April 2020 was carried out using PUBMED, Scopus, Cochrane, and Google Scholar. In this review, we focused on people over 65 years old at different care levels. The results show that the mean fluid intake ranges between 311 and 2390 mL/day. However, it is difficult to know whether this corresponds to the real pattern of fluid intake, due to the variability of data collection methods. With respect to the recommendations, most international organizations do not take into consideration the physiology of ageing or the health problems associated with an older population. In conclusions, we recommend to follow the guideline of the European Society for Clinical Nutrition and Metabolism (ESPEN) and the European Food Safety Authority (EFSA). ESPEN is the only guideline which takes into account age. It is also based on EFSA recommendations. This authority takes into consideration all fluids consumed (ranging from food to fluids). If it is known that around 20% of all fluids consumed come from food, the result would effectively be that the EFSA recommends the same as the ESPEN guidelines: 1.6 L/day for females and 2.0 L/day for males. The findings could help raise the awareness of professionals in the sector with respect to the required fluid intake of the elderly and, in this way, contribute to avoiding the consequences of dehydration.

Investigating the Relationship Between Age and Kidney Failure in Adults With Category 4 Chronic Kidney Disease

Background:

In people with severe chronic kidney disease (CKD), there is an inverse relationship between age and kidney failure. If this relationship is the same at any age (linear), one effect (hazard ratio) will be sufficient for accurate risk prediction; if it is nonlinear, the effect will vary with age.

Objective:

To investigate the relationship between age and kidney failure in adults with category G4 chronic kidney disease (G4 CKD).

Methods:

We performed a population-based study using linked administrative databases in Alberta, Canada, to study adults with G4 CKD (estimated glomerular filtration rate [eGFR] = 15-30 mL/min/1.73 m²) and without previously documented eGFR <15 mL/min/1.73 m² or renal replacement. We used cause-specific Cox regression to model the relationship between age and the hazard of kidney failure (the earlier of eGFR <10 mL/min/1.73 m² or receipt of renal replacement) and death, incorporating spline terms to capture any nonlinear effect of age. We included sex, diabetes mellitus, cardiovascular disease, albuminuria, and eGFR in all models.

Results:

Of the 27 823 participants (97 731 patient-years at risk; mean age = 76 years, ±13), 19% developed kidney failure and 51% died. The decline in the hazard of kidney failure associated with a given increase in age was not constant but became progressively larger as people aged; that is, the hazard ratio became progressively smaller (closer to 0). Assuming an eGFR of 25 mL/min/1.73 m², for every 10-year increase in age, the hazard ratio declined from 0.76 (95% confidence interval = 0.73-0.79) at age 50 years to 0.43 (95% confidence interval = 34-56) at age 80 years in people without cardiovascular disease, and from 0.75 (95% confidence interval = 0.70-0.79) at age 50 years to 0.36 (95% confidence interval = 0.29-0.45) at age 80 years in people with cardiovascular disease.

Conclusions:

The relationship between kidney failure and age varies with age. An age-dependent effect, rather than a constant effect, needs to be specified to accurately predict risk. These findings have implications for risk prediction and advanced care planning.

Association of Age With Risk of Kidney Failure in Adults With Stage IV Chronic Kidney Disease in Canada

Importance

With population aging, the burden of many age-related chronic conditions, including kidney failure, is increasing globally.

Objective

To investigate the risks of kidney failure and death in adults with incident stage IV chronic kidney disease (CKD).

Design, Setting, and Participants

This population-based cohort study obtained data recorded between July 30, 2002, and March 31, 2014, from the linked laboratory and administrative data set of Alberta Health in Alberta, Canada. All adults of the province of Alberta with stage IV CKD (estimated glomerular filtration rate [eGFR] of 15-30 mL/min/1.73 m2) were eligible for inclusion. Included individuals were followed up from study entry until the date of kidney failure, death, or censoring, whichever occurred first. Observations were censored at the date of emigration from the province, the study end date (March 31, 2017), or at 10 years after study entry. Data analyses were performed from January 2020 to June 2020.

Main Outcomes and Measures

The primary outcome was kidney failure, defined as the earlier of either renal replacement (dialysis or kidney transplant) initiation or severe kidney impairment (eGFR <10 mL/min/1.73 m2). Incidence of stage IV CKD in Alberta was examined over time, along with the association between age at study entry and the competing risks of kidney failure and death. Cumulative incidence functions (95% CIs) were estimated to summarize absolute risks over time across categories of age, accounting for sex, diabetes, cardiovascular disease, eGFR, and albuminuria.

Results

The study included 30 801 adults (mean [SD] age, 76.8 [13.3] years; 17 294 women [56.1%]) with stage IV CKD. Of these, 5511 developed kidney failure (17.9%) and 16 285 died (52.9%). The incidence rate of stage IV CKD increased sharply with advancing age; the absolute risk of kidney failure decreased with advancing age, and the risk of death increased, especially in those aged 85 years or older. Compared with the 5-year risk of death, the 5-year risk of kidney failure was higher in people younger than 65 years, similar in people aged 65 to 74 years, and lower for older age groups. For those aged 75 years or older, the risk of death was much higher than the risk of kidney failure: 6-fold higher among those aged 75 to 84 years (0.51 [95% CI, 0.5-0.52] vs 0.09 [95% CI, 0.08-0.09]) and 25-fold higher among those aged 85 years or older (0.75 [95% CI, 0.74-0.76] vs 0.03 [95% CI, 0.02-0.03]). The risk of death was higher than the risk of kidney failure by 24-fold among those aged 85 to 94 years (0.73 [95% CI, 0.72-0.74] vs 0.03 [95% CI, 0.02-0.03]) and by 149-fold among those aged 95 years or older (0.89 [95% CI, 0.87-0.92] vs <0.01 [95% CI, <0.01 to 0.01]).

Conclusions and Relevance

This study found that, although the incidence rate of stage IV CKD increased with advancing age, the absolute risk of kidney failure decreased. Unlike other age-related conditions, the expected increase in the burden of kidney failure in the older adults may be less dramatic than expected.

Involvement of sex hormones, oxidative stress, ACE and ACE2 activity in the impairment of renal function and remodelling in SHR

AIMS

Hypertension is a relevant sex and sex hormones-dependent risk factor where the cardiovascular and renal health of the population are concerned. Men experience greater losses of renal function (RF) than women, but the mechanisms remain somewhat unclear. Our goal was to evaluate the relationship between oxidative stress (OS), angiotensin-converting enzyme (ACE) and angiotensin-converting enzyme 2 (ACE2) activities and RF in male and female SHR.

MAIN METHODS

Twelve-week-old spontaneously hypertensive rats (SHR) were submitted to either castration or SHAM surgery and divided into 4 groups, SHAM or Castrated (CAST) males or females. After 51 days we evaluated RF (inulin and sodium para-aminohippurate), ACE and ACE2 activities (fluorimetry), OS (flow cytometry), collagen deposition (picrosirius red) and protein expression (western blot).

KEY FINDINGS

Males presented lower RF than females and castration impaired this parameter in both groups. Sexual dimorphism was not observed regarding OS and inflammation; however, castration increased this parameter more severely in males than in females. SHAM males exhibited higher collagen deposition than females, though castration increased it in both sexes, eliminating the difference. We found sexual dimorphism regarding renal ACE and ACE2 activities, which were lower in males than in females. Although castration did not alter ACE activity, it reduced ACE2 activity in females and increased it in males.

SIGNIFICANCE

These results indicate that sex hormones affect RF in SHR. As alterations in the oxidative system were capable of promoting podocyte injury, inflammation, and collagen deposition, we put forward that these effects are differently modulated by ACE and ACE2.

Diagnostic value of the Modification of Diet in Renal Disease and Chronic Kidney Disease Epidemiology Collaboration equations in diabetic patients: a systematic review and meta-analysis

BACKGROUND

The Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) and Modification of Diet in Renal Disease (MDRD) equations are common for calculating estimated glomerular filtration rate (eGFR). Unlike CKD, the key pathological change of diabetic kidney disease (DKD) is glomerulosclerosis.

METHODS

To conduct a meta-analysis of the diagnostic performance of the CKD-EPI and MDRD equations in diabetic patients, we searched PubMed, Embase and the Cochrane Library for studies comparing standard GFR (sGFR) with eGFR using these two equations.

RESULTS

Thirteen studies of 7192 diabetic patients reporting data on bias or accuracy were included. At the study level, both equations underestimated eGFR. CKD-EPI was more accurate in studies with mean GFR ≥60 mL/minute/1.73 m². At the individual level, both equations overestimated GFR by 6.38 mL/minute/1.73 m² (95% confidence interval [CI] 2.67-10.1) and 7.65 mL/minute/1.73 m² (95% CI 2.78-12.52), respectively, for sGFR < 90 mL/minute/1.73 m². The CKD-EPI equation was 7.61% (95% CI 4.66-10.56) more accurate in subjects with sGFR > 90 mL/minute/1.73 m². The CKD-EPI equation performed poorly in diabetic patients.

CONCLUSIONS

The CKD-EPI equation can be used to estimate GFR in patients with incipient DKD, but has drawbacks. Improved eGFR equations suitable for diabetic populations are needed.

Variability in the incidence of renal replacement therapy over time in Western industrialized countries: A retrospective registry analysis

Introduction

A growing number of patients started renal replacement therapy (RRT) in Western industrialized countries between 1980 an early 2000s. Thereafter reports from national and international registries suggest a trend towards stabilization and sometimes a decrease in the incidence rate.

Aim

To investigate the differences in overall and age-specific incidence rates between industrialized countries from 1998 until 2013. Secondly, to investigate changes in incidence rates over time and their association with specific age categories.

Method

We extracted the unadjusted overall incidence of RRT and age-specific incidence rates from renal registry reports in Europe, the United States, Canada, Australia and New Zealand. Time trends in the incidence rate by country and age categories were analyzed by Joinpoint regression analysis.

Results

The incidence rate in 2013 ranged from 89 per million population (pmp) in Finland to 363 pmp in the US. Incidence rates in the lower age categories (20–64 year) were similar between countries and remained stable over time. Higher incidence countries were characterized by higher numbers of patients in both the 65–74 and ≥75 year categories starting RRT.

Joinpoint analysis confirmed that most countries had significant reductions in the incidence rate at the end of the study period. These reductions were explained by lower numbers of older patients starting RRT and were observed also in countries with lower overall incidence rates.

Conclusion

This study confirmed different incidence rates of RRT between industrialized countries worldwide. Countries with the highest overall incidence rates also had the highest incidence rates in the oldest age categories. Since the early 2000’s the number of older patients starting RRT is either stabilizing or even decreasing in most countries. This reduction is universal and is also observed in countries with previously low incidence rates.

GFR in Healthy Aging: an Individual Participant Data Meta-Analysis of Iohexol Clearance in European Population-Based Cohorts

BACKGROUND

Population mean GFR is lower in older age, but it is unknown whether healthy aging is associated with preserved rather than lower GFR in some individuals.

METHODS

We investigated the cross-sectional association between measured GFR, age, and health in persons aged 50-97 years in the general population through a meta-analysis of iohexol clearance measurements in three large European population-based cohorts. We defined a healthy person as having no major chronic disease or risk factors for CKD and all others as unhealthy. We used a generalized additive model to study GFR distribution by age according to health status.

RESULTS

There were 935 (22%) GFR measurements in persons who were healthy and 3274 (78%) in persons who were unhealthy. The mean GFR was lower in older age by -0.72 ml/min per 1.73 m² per year (95% confidence interval [95% CI], -0.96 to -0.48) for men who were healthy versus -1.03 ml/min per 1.73 m² per year (95% CI, -1.25 to -0.80) for men who were unhealthy, and by -0.92 ml/min per 1.73 m² per year (95% CI, -1.14 to -0.70) for women who were healthy versus -1.22 ml/min per 1.73 m² per year (95% CI, -1.43 to -1.02) for women who were unhealthy. For healthy and unhealthy people of both sexes, both the 97.5th and 2.5th GFR percentiles exhibited a negative linear association with age.

CONCLUSIONS

Healthy aging is associated with a higher mean GFR compared with unhealthy aging. However, both the mean and 97.5 percentiles of the GFR distribution are lower in older persons who are healthy than in middle-aged persons who are healthy. This suggests that healthy aging is not associated with preserved GFR in old age.

Dietary plant and animal protein intake and decline in estimated glomerular filtration rate among elderly women: a 10-year longitudinal cohort study

Background

Many older women demonstrate an age-related accelerating rate of renal decline that is associated with increased rates of bone disease, cardiovascular disease and mortality. Population-based protein restriction has been studied principally in patients with reduced renal function. In this investigation, we examined the hypothesis of a differential effect of plant-derived protein compared with animal-derived protein on renal function in older women.

Methods

We assessed dietary intake from a validated food frequency questionnaire and the estimated glomerular filtration rate (eGFR) (using the Chronic Kidney Disease Epidemiology Collaboration creatinine and cystatin C equation) at baseline, 5 and 10 years in the Longitudinal Study of Aging Women cohort. We tested the association between plant- and animal-sourced protein intake and kidney function using linear mixed modeling.

Results

A total of 1374 Caucasian women [mean (standard deviation, SD) age = 75 years (2.7) and mean (SD) baseline eGFR = 65.6 mL/min/1.73 m2 (13.1)] contributed to the analysis. The average decline in eGFR was 0.64 mL/min/1.73 m2/year [95% confidence interval (CI) 0.56–0.72]. Higher intakes of plant-sourced protein were associated with slower declines in eGFR after adjusting for covariates including animal protein and energy intake (P = 0.03). For each 10 g of plant protein, the yearly decline in eGFR was reduced by 0.12 mL/min/1.73 m2 (95% CI 0.01–0.23), principally associated with fruit-, vegetable- and nut-derived protein. The intake of animal protein was not associated with eGFR decline (P = 0.84).

Conclusions

Older women consuming a diet that is richer in plant-sourced protein have a slower decline in kidney function. These data extend support for the health benefits of plant-rich diets in the general population to maintain kidney health.