Clinical Implications of Estimating Glomerular Filtration Rate with Three Different Equations Among Older People. Preliminary Results of the Project "Screening for Chronic Kidney Disease among Older People across Europe (SCOPE)"

Renal function assessment in older people: comparative analysis of estimation equation with serum creatinine

Introduction

Age-related changes occurring in the kidney can lead to a reduction in Glomerular Filtration Rate (GFR); especially in older adults with multimorbidity and/or frailty, an accurate evaluation of kidney function is critical. For the estimation of GFR in patients over 70 years, CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) is often used. However, validated equations exist for old-age populations like BIS1 (Berlin Initiative Study 1) and FAS (Full Age Spectrum). Here we aimed to compare the performance of CKD-EPI, MDRD (Modification of Diet in Renal Disease), BIS1, and FAS in assessing eGFR in a population of patients over 70, to evaluate which equations show the most accurate performance in our setting.

Materials and methods

A total of 499 older adults were consecutively recruited in the Orthogeriatric ward and Oncogeriatrics clinic of IRCCS Polyclinic San Martino in Genoa Italy. eGFR was calculated using CKD-EPI, MDRD, BIS1, and FAS, calculating mean, median, standard deviation, and interquartile range. Bland-Altman graphs were used to evaluate how each equation performs with respect to the others and the concordance of the attribution of the KDIGO CKD stage was performed with Cohen's K constant and chi-squared test.

Results

Patients' mean age was 82.6 years (± 7.44), and the mean creatinine value was 0.97 (± 0.71) mg/dl. The mean value of eGFR was 70 mL/min with CKD-EPI (± 20.6) and MDRD (± 25.7), 57 mL/min with BIS1 (± 16.7) and FAS (± 19.0), respectively. BIS1 and FAS estimated lower eGFR values than CKD-EPI and MDRD. As age increases, a steady decrease in filtrate value is observed with BIS1 and FAS. MDRD and CDK-EPI do not show the same trend. The performance of the equations at a fixed eGFR value of 30 mL/min is more linear for BIS1 and FAS compared with CKD-EPI and MDRD. Upon evaluation with chi-square, the attribution of KDIGO stage was statistically different among the various equations.

Discussion

An appropriate assessment of renal function is of key clinical relevance to prevent adverse outcomes and risk of drug accumulation in older adults. Our study originally showed that in persons aged more than 70 years old BIS1 is the most accurate formula in calculating eGFR values when only serum creatinine is available.

Prevalence, risk factors, and treatment of anemia in hospitalized older patients across geriatric and nephrological settings in Italy

Anemia is a common but often underdiagnosed and undertreated geriatric syndrome in hospitalized older patients. In this retrospective multicenter study, we aimed at characterizing the prevalence, risk factors, diagnostic and treatment approach to anemia in older patients admitted to acute care hospitals, focusing on differences between nephrology and geriatrics units. Prevalence and risk factors for anemia, diagnostic inertia (lack of iron, vitamin B12, and folate status assessment), replacement inertia (omitted treatment with iron, vitamin B12 or folic acid), and erythropoiesis-stimulating agents (ESA) inertia were explored. 1963 patients aged 82.7 (6.8) years were included in the study; 66.7% of the study population had anemia; among anemic patients, diagnostic inertia and replacement inertia were common with rates of 22-31% and 50-87%, respectively; omitted treatment with ESA affected 67.2% of patients and was more prevalent in geriatric units. In most cases, patients with ESA inertia were not routinely screened for iron tests. COPD, cancer, eGFR 45-60 ml/min were associated with increased tendency to ESA inertia. In conclusion, anemia had a high prevalence in older patients discharged from acute care units, but it is often underdiagnosed and undertreated.

Biomarkers of chronic kidney disease in older individuals: navigating complexity in diagnosis

Chronic kidney disease (CKD) in older individuals is a matter of growing concern in the field of public health across the globe. Indeed, prevalence of kidney function impairment increases with advancing age and is often exacerbated by age-induced modifications of kidney function, presence of chronic diseases such as diabetes, hypertension, and cardiovascular disorders, and increased burden related to frailty, cognitive impairment and sarcopenia. Accurate assessment of CKD in older individuals is crucial for timely intervention and management and relies heavily on biomarkers for disease diagnosis and monitoring. However, the interpretation of these biomarkers in older patients may be complex due to interplays between CKD, aging, chronic diseases and geriatric syndromes. Biomarkers such as serum creatinine, estimated glomerular filtration rate (eGFR), and albuminuria can be significantly altered by systemic inflammation, metabolic changes, and medication use commonly seen in this population. To overcome the limitations of traditional biomarkers, several innovative proteins have been investigated as potential, in this review we aimed at consolidating the existing data concerning the geriatric aspects of CKD, describing the challenges and considerations in using traditional and innovative biomarkers to assess CKD in older patients, highlighting the need for integration of the clinical context to improve biomarkers' accuracy.

Association of dietary proteins with serum creatinine and estimated glomerular filtration rate in a general population sample: the CHRIS study

BACKGROUND

Diet is known to affect kidney function. However, population-based studies provide contrasting evidence, resulting in a poor understanding of the effect of proteins from specific foods on kidney health.

METHODS

We analyzed the effect of total daily protein intake (TDPI) and source-specific daily protein intake (DPI) on fasting serum creatinine (SCr) and estimated glomerular filtration rate (eGFR) in the Cooperative Health Research In South Tyrol (CHRIS) cross-sectional study (n = 5889), using the GA²LEN food frequency questionnaire for TDPI and DPI estimation. We fitted multivariable adjusted mixed models of SCr and eGFR on TDPI and DPI quartiles (Q1-Q4) in the overall sample, and after removing individuals with known hypertension, diabetes or chronic kidney disease (CKD).

RESULTS

Higher TDPI as well as DPI from overall animal sources, fish, and poultry, were associated with higher SCr (trend test p, p_trend < 0.01), with larger effect after excluding individuals with known hypertension, diabetes or CKD. The eGFR was lower at higher TDPI (Q4 vs Q1: - 1.6 ml/min/1.73 m²; 95% CI - 2.5, - 0.7; p_trend = 3e-4) and DPI from fish (Q4 vs Q1: - 2.1 ml/min/1.73 m²; 95% CI - 2.9, - 1.20; p_trend = 4.3e-6), overall animal source (Q4 vs Q1: - 1.6 ml/min/1.73 m²; 95% CI -2.5, - 0.8), processed meat (Q4 vs Q1: - 1.4 ml/min/1.73 m²; p_trend = 0.027), red meat, offal and processed meat (Q4 vs Q1: - 1.4 ml/min/1.73 m²; p_trend = 0.015) and poultry (Q4 vs Q1: - 0.9 ml/min/1.73 m²; p_trend = 0.015).

CONCLUSIONS

TDPI and DPI from specific animal sources were positively associated with SCr and negatively associated with eGFR. Lacking an alternative marker of kidney function, confounding involving muscle mass metabolism cannot be fully excluded.

Clinical and Prognostic Implications of Estimating Glomerular Filtration Rate by Three Different Creatinine-Based Equations in Older Nursing Home Residents

Background

According to the international literature, the percentage of nursing home (NH) residents with renal insufficiency is very high, ranging between 22 and 78%. Diminished kidney function represents a risk factor for drug overdosage, adverse drug reactions, end-stage renal disease, disability, morbidity, and mortality. Several studies suggested that screening for chronic kidney disease (CKD) in high-risk and older populations may represent a cost-effective approach to reducing progression to renal failure and CKD mortality.

Objective

This study aimed (i) to investigate to what extent CKD may be staged interchangeably by three different creatinine-based estimated glomerular filtration rate (eGFR) equations in a sample of older adults living in long-term care facilities; (ii) to investigate factors explaining differences among eGFR equations; and (iii) to compare the predictivity of different creatinine-based eGFR equations with respect to all-cause mortality.

Methods

A total of 522 residents aged 65 years and older participated in a prospective cohort study of 9 long-term care facilities in Calabria. eGFR was calculated by Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI), Berlin initiative study (BIS), and full age spectrum (FAS) equations. Disability in at least one activity of daily living (ADL), depression, cognitive impairment, comorbidity, and malnutrition was considered in the analysis. Statistical analysis was carried out by Bland-Altman analysis, and 2-year mortality was investigated by Kaplan-Meier curves and Cox regression analysis.

Results

Depending on the adopted equation, the prevalence of NH residents with impaired renal function (eGFR < 60 ml/min/1.73 m²) ranged between 58.2% for the CKD-EPI and 79.1% for the BIS1 equation. The average difference between BIS and FAS was nearly negligible (0.45 ml/min/1.73 m²), while a significant bias was detected between CKD-EPI and BIS and also between CKD-EPI and FAS (6.21 ml/min/1.73 m² and 6.65 ml/min/1.73 m², respectively). Although the eGFR study equations had comparable prognostic accuracy in terms of mortality risk, BIS and FAS were able to reclassify NH residents pertaining to a low-risk group with CKD-EPI, and this reclassification improves the discriminative capacity of CKD-EPI with respect to overall mortality.

Conclusion

Despite the relatively good correlation between eGFRs calculated using all adopted equations, the findings in this study reported clearly demonstrated that CKD-EPI and BIS/FAS equations are not interchangeable to assess eGFR among older people and particularly in institutionalized and frail older subjects.

Associations between frailty, physical performance, and renal biomarkers in older people with advanced chronic kidney disease

Aim

To test whether renal biochemical markers were associated with physical performance and frailty in older people with advanced chronic kidney disease.

Findings

Biochemical markers associated with chronic kidney disease did not consistently associate with baseline physical performance or the rate of change of physical performance measures.

Message

Targeting improvements in renal biochemistry may not be a fruitful way to improve physical function and frailty in older people with advanced chronic kidney disease.

Supplementary Information

The online version of this article (10.1007/s41999-021-00478-4) contains supplementary material, which is available to authorized users.

Purpose

Impaired physical performance and frailty are common in older people with advanced chronic kidney disease but it is unclear which metabolic derangements contribute to these impairments. We, therefore, examined associations between renal biochemical markers and both physical performance and frailty in older people with advanced chronic kidney disease.

Methods

Secondary analysis of data from the BiCARB trial, which enrolled non-dialysing patients aged 60 and over, with chronic kidney disease stage 4/5, with serum bicarbonate < 22 mmol/L. Participants undertook the Short Physical Performance Battery, maximum grip strength and six-minute walk test at baseline, 3, 6, 12 and 24 months. Renal biochemistry (serum creatinine, cystatin C, phosphate, and bicarbonate), haemoglobin, 25-hydroxyvitamin D and NT-pro-B-type natriuretic peptide were measured at baseline. Associations between baseline renal biochemistry and physical performance, and between baseline biochemistry and the monthly rate of change in physical performance were assessed.

Results

We analysed data from 300 participants (mean age 74 years; 86 [29%] women). 148 (49%) were pre-frail, 86 (29%) were frail. In multivariable cross-sectional baseline analyses, only age and BMI were significantly associated with baseline short physical performance battery; age, sex, body mass index, NT-pro-BNP and 25-hydroxyvitamin D were significantly associated with baseline six-minute walk distance. No significant associations were found between biochemical markers and change in physical performance over time, except between baseline 25-hydroxyvitamin D concentration and change in six-minute walk distance.

Conclusions

Biochemical markers associated with chronic kidney disease did not consistently associate with baseline physical performance or the rate of change of physical performance measures.

Trial Registration: ISRCTN09486651

Supplementary Information

The online version of this article (10.1007/s41999-021-00478-4) contains supplementary material, which is available to authorized users.

Alterations in drug disposition in older adults: a focus on geriatric syndromes

INTRODUCTION

Age-associated physiological changes can alter the disposition of drugs, however, pathophysiological changes associated with geriatric syndromes in older adults may lead to even greater heterogeneity in pharmacokinetics. Geriatric syndromes are common health problems in older adults which have multifactorial causes and do not fit into distinct organ-based disease categories. With older adults being the greatest users of medications, understanding both age- and geriatric syndrome-related changes is important clinically to ensure safe and effective medication use.

AREAS COVERED

This review provides an overview of current evidence regarding pharmacokinetic alterations that occur with aging and in common geriatric syndromes, including frailty, sarcopenia, dementia, polypharmacy and enteral feeding. The evidence is presented according to the four primary pharmacokinetic processes (Absorption, Distribution, Metabolism and Excretion).

EXPERT OPINION

There is some evidence to inform our understanding of the impact of chronological aging and various geriatric syndromes on drug disposition. However, many areas require more research, including drug induced inhibition and induction of cytochrome P450 enzymes and the clinical utility of emerging methods for estimating renal function. There is a need to develop tools to predict alterations in drug disposition in subgroups of older adults, particularly where the currently available clinical information is sparse.

Diabetic Kidney Disease in Older People with Type 2 Diabetes Mellitus: Improving Prevention and Treatment Options

Age-related metabolic and renal changes predispose older people to an increased risk of diabetes mellitus and diabetic kidney disease, respectively. As the prevalence of the ageing population is increasing, because of increased life expectancy, the prevalence of older people with diabetic kidney disease is likely to increase. Diabetic kidney disease is associated with an increased risk of adverse outcomes and increased costs to healthcare systems. The management includes promotion of a healthy lifestyle and control of cardiovascular risk factors such as hyperglycaemia, hypertension and dyslipidaemia. Older people are a heterogeneous group of people from a community-living fit and independent person to a fully dependent individual residing in a care home. Therefore, management in this age group should be based on a patient's functional level adopting tight metabolic control in the fit individual and relaxed targets in the frail person. However, despite the maximum available therapy, a significant number of patients with diabetic kidney disease still progress to renal failure and experience adverse cardiac outcomes. Therefore, future research is required to explore methods of early detection of diabetic kidney disease and to investigate novel therapeutic interventions to further improve the outcomes.