Agreement between Chronic Kidney Disease Epidemiological Collaboration and Berlin Initiative Study equations for estimating glomerular filtration rate in older people: The Invecchiare in Chianti (Aging in Chianti Region) study

Chronic kidney disease in the elderly and frail patient: perspectives with opinions and comments

Chronic kidney disease is common in elderly and frail people. The importance of age in staging chronic kidney disease is discussed as well as the possible constraints of staging what is actually a 'continuum' of disease progression. Frailty is a biological state characterized by the decline of several physiological systems and strongly correlated with adverse health outcomes, including mortality. Frailty is measured by the Comprehensive Geriatric Assessment, which focuses on quantitative rating scales that determine not only the clinical profile and pathological risk of frail individuals, but also their residual capacities, functional status, and quality of life. There is circumstantial evidence that Comprehensive Geriatric Assessment can improve both survival and quality of life in elderly chronic kidney disease patients. Despite the long list of emerging risk factors and markers of chronic kidney disease progression, it is the authors' opinion that a single biochemical parameter can hardly cover the complexity of chronic kidney disease in elderly and frail patients. Among the numerous clinical scores proposed, the European Renal Best Practice guidelines recommend the Renal Epidemiology and Information Network score and the Kidney Failure Risk Equations. The former provides a reasonable estimate of short-term mortality risk, the latter provides the risk of chronic kidney disease progression. In conclusion, the elderly individual with advanced chronic kidney disease is often comorbid and frail with peculiarities in terms of disease grading, clinical assessment and monitoring. The time has come to reshape the care of this growing number of patients by focusing on multidisciplinary teams both in the hospital and in the community.

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.

The practicality of different eGFR equations in centenarians and near-centenarians: which equation should we choose?

Background

No studies have examined the practicality of the Modification of Diet in Renal Disease (MDRD), Chronic Kidney Disease Epidemiological Collaboration (CKD-EPI) and Berlin Initiative Study 1 (BIS1) equations for the estimated glomerular filtration rate (eGFR) in a large sample of centenarians. We aim to investigate the differences among the equations and suggest the most suitable equation for centenarians and near-centenarians.

Methods

A total of 966 centenarians and 787 near-centenarians were enrolled, and the eGFR was calculated using the three equations mentioned above. Agreement among the equations was investigated with the κ statistic and Bland-Altman plots. Sources of discrepancy were investigated using a partial correlation analysis.

Results

The three equations for assessing eGFR are not considered interchangeable in centenarians and near-centenarians. Δ(MDRD, CKD-EPI) and Δ(MDRD, BIS1) increased with age, but Δ(CKD-EPI, BIS1) was relatively stable with age. Δ(MDRD, CKD-EPI) and Δ(MDRD, BIS1) were considerable in subjects with Scr levels less than 0.7 mg/dL and decreased with the Scr level. A considerable difference between CKD-EPI and BIS1 was observed for participants with Scr levels ranging from 0.5 to 1.5 mg/dL. This difference increased with Scr levels ranging from 0.5 to 0.7 mg/dL, was relatively stable for Scr levels ranging from 0.7 to 0.9 mg/dL, and decreased with Scr levels ranging from 0.9 to 1.5 mg/dL. The differences in the three comparisons were all greater in women than in men (p < 0.05).

Conclusions

We tend to suggest the MDRD equation to calculate the glomerular filtration rate (GFR) in elderly individuals >95 years old who have no risk factors for cardiovascular disease; the BIS1 equation to calculate the eGFR for elderly individuals younger than 94 years old who have risk factors for cardiovascular disease; the CKD-EPI equation to calculate the eGFR of elderly individuals with Scr levels greater than 1.5 mg/dL; and the BIS1 equation to calculate the eGFR of older women with Scr levels less than 0.7 mg/dL.

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)"

We aimed at investigating to what extent CKD may be staged interchangeably by three different eGFR equations in older people, and evaluating the source of discrepancies among equations in a population of 2257 patients older than 75 years enrolled in a multicenter observational study. eGFR was calculated by CKD-EPI, BIS and FAS equations. Statistical analysis was carried out by Bland–Altman analysis. κ statistic was used to quantify the agreement between equations in classifying CKD stages. The impact of selected variables on the difference among equations was graphically explored. The average difference between BIS and FAS was −0.24 (95% limits of agreement (95%LA = −4.64–4.14) mL/min/1.73 m². The difference between CKD-EPI and BIS and between CKD-EPI and FAS was 8.97 (95%LA = −2.90–20.84) and 8.72 (95%LA = −2.11–19.56) mL/min/1.73 m², respectively. As regards CKD stage classification, κ value was 0.47 for both CKD-EPI vs. FAS and CKD-EPI vs. BIS, while BIS and FAS had similar classificatory properties (κ = 0.90). Muscle mass was found related to the difference between CKD-EPI and BIS (R² = 0.11) or FAS (R² = 0.14), but not to the difference between BIS and FAS. In conclusion, CKD-EPI and BIS/FAS equations are not interchangeable to assess eGFR among older people. Muscle mass may represent a relevant source of discrepancy among eGFR equations.

[Concordance between the equations "Chronic Kidney Disease Epidemiological Collaboration" and "Modification of Diet in Renal Disease" with the "Berlin Initiative Study" to estimate renal function in the elderly]

OBJECTIVE

Estimated glomerular filtration rate (eGFR) is calculated routinely using creatinine-based formulas, but their reliability in the elderly is limited. The aim of this study was to analyse the concordance between the BIS1 equation which is specific for the elderly, and the usual CKD-EPI and MDRD-IDMS in a large population over 70 years of age.

MATERIAL AND METHODS

Retrospective cross-sectional study in which the eGFR was calculated using BIS1, CKD-EPI and MDRD-IDMS equations based on gender, age, and creatinine data of 85,089 subjects (58.5% women, mean age 78 years [IQR 73-83]).The following statistics were carried out: Wilcoxon test, Bland-Altman graphic analysis, study of the concordance using the intraclass correlation coefficient (ICC), and comparison tables for the classification of CKD.

RESULTS

The median of the eGFRs using BIS1 was 58mL/min/1.73m² (IQR 48-70), using CKD-EPI was 68mL/min/1.73m² (IQR 53-84), and using MDRD it was 68mL/min/1.73m² (IQR 53-82). The concordance between BIS1 and CKD-EPI (intraclass correlation coefficient =0.87) was found to be acceptable. It was lower with MDRD (intraclass correlation coefficient =0.81). A mean difference of 8mL/min/1.73m² (SD 2.6-18) was found BIS1 vs. CKD-EPI, and 10mL/min/1.73m² (SD 6-27) with BIS1 vs. MDRD, which was maintained when stratifying by gender and age groups.

CONCLUSIONS

Despite the acceptable statistical agreement, the eGFR obtained with the BIS1 equation is not interchangeable with CKD-EPI or with MDRD-IDMS. The BIS1 equation gives lower values than CKD-EPI, and classifies patients into a higher level of CKD, mainly when the eGFR is above 30mL/min/1.73 m².

Beyond chronic kidney disease: the diagnosis of Renal Disease in the Elderly as an unmet need. A position paper endorsed by Italian Society of Nephrology (SIN) and Italian Society of Geriatrics and Gerontology (SIGG)

The dramatic increase in prevalence of chronic kidney disease (CKD) with ageing makes the recognition and correct referral of these patients of paramount relevance in order to implement interventions preventing or delaying the development of CKD complications and end-stage renal disease. Nevertheless, several issues make the diagnosis of CKD in the elderly cumbersome. Among these are age related changes in structures and functions of the kidney, which may be difficult to distinguish from CKD, and multimorbidity. Thus, symptoms, clinical findings and laboratory abnormalities should be considered as potential clues to suspect CKD and to suggest screening. Comprehensive geriatric assessment is essential to define the clinical impact of CKD on functional status and to plan treatment. Correct patient referral is very important: patients with stage 4-5 CKD, as well as those with worsening proteinuria or progressive nephropathy (i.e. eGFR reduction > 5 ml/year) should be referred to nephrologist. Renal biopsy not unfrequently may be the key diagnostic exam and should not be denied simply on the basis of age. Indeed, identifying the cause(s) of CKD is highly desirable to perform a targeted therapy against the pathogenetic mechanisms of CKD, which complement and may outperform in efficacy the general measures for CKD.

Analysis of chronic kidney disease staging with different estimated glomerular filtration rate equations in Chinese centenarians

Background:

Accurate estimation of the glomerular filtration rate (GFR) and staging of chronic kidney disease (CKD) are important. Currently, there is no research on the differences in several estimated GFR equations for staging CKD in a large sample of centenarians. Thus, this study aimed to investigate the differences in CKD staging with the most commonly used equations and to analyze sources of discrepancy.

Methods:

A total of 966 centenarians were enrolled in this study from June 2014 to December 2016 in Hainan province, China. The GFR with the Modification of Diet in Renal Disease (MDRD), Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) and Berlin Initiative Study 1 (BIS1) equations were estimated. Agreement between these equations was investigated with the κ statistic and Bland-Altman plots. Sources of discrepancy were investigated by partial correlation analysis.

Results:

The κ values of the MDRD and CKD-EPI equations, MDRD and BIS1 equations, and CKD-EPI and BIS1 equations were 0.610, 0.253, and 0.381, respectively. Serum creatinine (Scr) explained 10.96%, 41.60% and 17.06% of the variability in these three comparisons, respectively. Serum uric acid (SUA) explained 3.65% and 5.43% of the variability in the first 2 comparisons, respectively. Gender was associated with significant differences in these 3 comparisons (P < 0.001).

Conclusions:

The strengths of agreement between the MDRD and CKD-EPI equations were substantial, but those between the MDRD and BIS1 equations and the CKD-EPI and BIS1 equations were fair. The difference in CKD staging of the first 2 comparisons strongly depended on Scr, SUA and gender, and that of CKD-EPI and BIS1 equations strongly depended on Scr and gender. The incidence at various stages of CKD staging was quite different. Thus, a new equation that is more suitable for the elderly needs to be built in the future.

When kidneys and lungs suffer together

A significant interaction between kidneys and lungs has been shown in physiological and pathological conditions. The two organs can both be targets of the same systemic disease (eg., some vasculitides). Moreover, loss of normal function of either of them can induce direct and indirect dysregulation of the other one. Subjects suffering from COPD may have systemic inflammation, hypoxemia, endothelial dysfunction, increased sympathetic activation and increased aortic stiffness. As well as the exposure to nicotine, all the foresaid factors can induce a microvascular damage, albuminuria, and a worsening of renal function. Renal failure in COPD can be unrecognized since elderly and frail patients may have normal serum creatinine concentration. Lungs and kidneys participate in maintaining the acid-base balance. Compensatory role of the lungs rapidly expresses through an increase or reduction of ventilation. Renal compensation usually requires a few days as it is achieved through changes in bicarbonate reabsorption. Chronic kidney disease and end-stage renal diseases increase the risk of pneumonia. Vaccination against Streptococcus pneumonia and seasonal influenza is recommended for these patients. Vaccines against the last very virulent H1N1 influenza A strain are also available and effective. Acute lung injury and acute kidney injury are frequent complications in critical illnesses, associated with high morbidity and mortality. The concomitant failure of kidneys and lungs implies a multidisciplinary approach, both in terms of diagnostic processes and therapeutic management.

Prevalence and determinants of differences in cystatin C and creatinine-based estimated glomerular filtration rate in community-dwelling older adults: a cross-sectional study

Background

Differences in cystatin C and creatinine-based estimated glomerular filtration rate (eGFR) can lead to clinical uncertainty. Existing eGFR equations perform poorly in a subset of individuals. This study aims to describe the prevalence of differences between cystatin C-based (eGFR_cys) and creatinine-based (eGFR_creat) eGFR in older adults and to explore which subsets of individuals may be most affected by differing estimations.

Methods

In this cross-sectional study, participants from a cohort of community-dwelling older adults were examined at a baseline visit in 2001-2004 as part of the larger “Good Aging in Skåne” study. Exposure variables were obtained from questionnaires, interviews, examinations, and medical records. Blood samples were taken during the baseline visit, cryopreserved, and analyzed at a later time for biomarkers. The CKD-EPI equations were used to estimate GFR. Initial descriptive analyses were performed on 2931 individuals. A total of 2532 participants were included in the final multiple linear regression.

Results

Nearly two-thirds of participants had eGFR differences exceeding 10%, with nearly 20 % of participants having eGFR differences exceeding 30%. Smoking, age, body mass index (BMI), C-reactive protein (CRP), glucocorticoid use, and mean eGFR were correlated with differences between eGFR_creat and eGFR_cys.

Conclusions

Differences between eGFR_creat and eGFR_cys are common and often of large magnitude in this community-dwelling population of older adults. The finding of multiple non-GFR determinants correlated to differences in GFR estimations can help direct future research to improve eGFR equations for subgroups prone to conflicting GFR estimations or to guide choice of biomarker for GFR estimation in these subgroups.

Electronic supplementary material

The online version of this article (10.1186/s12882-017-0759-3) contains supplementary material, which is available to authorized users.