Estimating glomerular filtration rate: comparison of the CKD-EPI and MDRD equations in a large UK cohort with particular emphasis on the effect of age

How to Evaluate Kidney Function in Elite Endurance Athletes: Pros and Cons of Different Creatinine-Based Formulas

Background: Various creatinine-based equations are used to estimate the glomerular filtration rate (eGFR) in athletes, but each has limitations. The aim of our study was to identify the most suitable formula for use in athletes. Methods: We evaluated 490 Olympic athletes (27 ± 5.3 yo) with normal values of serum creatinine and no history of kidney diseases. Athletes were divided into those practicing skills and endurance disciplines. The EGFR was calculated with Cockcroft-Gault (CG), MDRD, MCQE and CKD-EPI, and classified as stages G1-G5 according to the Kidney Disease Improving Global Outcomes (KDIGO) GFR categories. Results: Endurance athletes showed higher serum creatinine (0.91 ± 0.14 mg/dL vs. 0.88 ± 0.13 mg/dL in skills, p = 0.014). The eGFR calculated with the CKD-EPI and MCQE formulas showed no differences between the groups. The CG formula produced a lower eGFR for endurance athletes (113.6 ± 27 mL/min/1.73 m2) compared to skills athletes (122.6 ± 30.8, p = 0.008), while MDRD produced higher values for endurance athletes (129.3 ± 25.8 vs. 122.6 ± 24 mL/min/1.73 m2, p = 0.004). According to CKD-EPI, all athletes were in G1, while with MCQE, 0.5% of skills athletes and 1% of endurance athletes were in G2. With the CG formula, a significant percentage of athletes were in G2 (13.2% of skills athletes and 18.5% of endurance athletes, p = 0.125). With the MDRD formula, 29 athletes (5.9%) were in G2 (6% for skills athletes and 5.8% for endurance athletes, p = 0.927). Conclusions: CKD-EPI and MCQE showed better stability and reliability, making them the most suitable for kidney function evaluation in athletes.

Chronic Kidney Disease Prevalence in India: A Systematic Review and Meta-Analysis From Community-Based Representative Evidence Between 2011 to 2023

Chronic kidney disease (CKD) prevalence varies widely across different regions of India. We aimed to identify the status of CKD in India, by systematically reviewing the published community-based studies between the period of January 2011 to December 2023. PubMed, Scopus, and EMBASE were searched for peer-reviewed evidence. Records identified for full-text screening were imported into the Litmaps literature review tool to identify more relevant studies. Two researchers independently examined and retrieved the data. Quality assessment was conducted using the JBI tool for prevalence studies. A random effects model pooled the estimates. Subgroup analysis, meta-regression and sensitivity analysis explored heterogeneity sources and estimated robustness. Publication bias was assessed with a DOI plot and LFK index. Among the 7062 records identified, 18 studies were included in this review. The pooled prevalence of CKD from community-based studies in India was 13.24% (confidence intervals (CI) 10.52 to 16.22, I2 99%, p < 0.001). CKD prevalence among men was 14.80%, while among women it was 13.51%. Southern administrative zone had a pooled CKD prevalence of 14.78%. Pooled CKD prevalence was higher in studies from rural areas (15.34%) compared to those from urban areas (10.65%). Significant heterogeneity was found. Subgroup analyses based on sampling strategy, quality score, publication year, and eGFR estimation equation showed no effect on the pooled prevalence. Prediction Intervals confirmed CKD prevalence in India in future studies will fall between 2.64% and 30.17%. This review indicates a rising trend of CKD (from 11.12% during the period 2011 to 2017, to 16.38% between 2018 to 2023) among Indians aged 15 years and above, over the past years. More future regional research is needed to tailor-make CKD interventions to detect early and manage well.

Estimated glomerular filtration rate calculated by serum creatinine lacks precision and accuracy in adults with type 2 diabetes with preserved renal function

AIMS

We evaluated the performance of creatinine-based equations that are currently used to estimate glomerular filtration rate (GFR) in people with type 2 diabetes compared to measured GFR using gold-standard methods.

METHODS

In this post-hoc analysis, 32 participants underwent repeated measurement of GFR by inulin clearance (mGFR). GFR was estimated by serum creatinine using the MDRD (eGFRMDRD) and CKD-EPI (eGFRCKD-EPI) equations four times over the course of one month. Performance was evaluated using measurements of bias (mean difference), precision (SD), and inaccuracy (proportion of eGFR that differed by >20 % of mGFR). Treatment and time effects on bias were evaluated using linear mixed effects models.

RESULTS

At baseline, participants (38 % female) were age 60 ± 8 years, had diabetes duration of 9 ± 7 years, HbA1c 56 ± 9 mmol/mol (7.2 ± 0.8 %), and BMI 31.0 ± 6.2 kg/m2. Mean mGFR was 113 ± 24, mean eGFRMDRD was 93 ± 12, and mean eGFRCKD-EPI was 94 ± 9 mL/min/1.73 m2. When 128 observations (32 participants measured 4 times) were evaluated, both equations substantially underestimated mGFR. For eGFRMDRD, mean bias was -21.5 mL/min/1.73 m2, precision was 22.7 mL/min/1.73 m2, and 46 % of observations differed by >20 %. Results were similar for eGFRCKD-EPI. No time or treatment effects on bias were observed.

CONCLUSIONS

In adults with type 2 diabetes and preserved renal function, eGFR equations underestimated mGFR, lacked precision and accuracy, and performance was lower at higher ranges of mGFR. Current eGFR equations by serum creatinine are inaccurate in adults with type 2 diabetes with preserved renal function, highlighting the necessity to develop new methods to measure kidney function at earlier stages of diabetic kidney disease.

Pro-Enkephalin and its association with renal function in Middle Eastern immigrants and native Swedes

Iraqi-born immigrants residing in Sweden exhibit lower blood pressure as well as better renal function despite an overall worse metabolic risk profile in comparison with native Swedes. This may indicate the presence of cardiorenal protective mechanisms in the Middle Eastern population. Hence, the aim of this study was to investigate whether the association between renal function and Pro-Enkephalin (PENK), a biomarker predictive of both acute and chronic kidney dysfunction, differs across ethnicities. The MEDIM population-based study including a cohort of women and men, born in Iraq or Sweden, aged 30-75 years was conducted in Malmö, Sweden, from 2010 to 2012. The study included fasting blood samples, physical examinations and self-administrated questionnaires. Despite significantly better renal function assessed by creatinine-based eGFR in the Iraqi group, levels of PENK did not differ between the groups, (70.0 pmol/L, born in Iraq (n = 1263) vs 71.1, born in Sweden (n = 689), p = .4). However, the association between PENK and renal function was relatively weaker in the Iraqi born group, as supported by a significant interaction between PENK and country of birth (P_Interaction= Country of birth x PENK = 0,010). This observational study suggests that the association between renal function and PENK was weaker in Middle Eastern immigrants. This is of interest as PENK may exhibit a direct effect on renal function, however further research is needed including studies on causality.

The predictive value of creatinine clearance for mortality in patients undergoing revascularization

Background

Renal function plays a significant role in the prognosis and management of patients with multi-vessel coronary artery disease (CAD) referred for revascularization. Current data lack precise risk stratification using estimated glomerular filtration rate (eGFR) and creatinine clearance.

Methods

This prospective study includes a three-year follow-up of 1112 consecutive patients with multi-vessel CAD enrolled in the 22 hospitals in Israel that perform coronary angiography.

Results

The Mayo formula yielded the highest mean eGFR (90 ± 26 mL/min per 1.73m²) and chronic kidney disease-epidemiology collaboration (CKD-EPI) the lowest (76 ± 24 mL/min per 1.73m²). Consequently, the Mayo formula classified more patients (56%) as having normal renal function. There was a significant and strong correlation between the values obtained from all five formulas using Cockcroft-Gault as the reference formula: Mayo: r = 0.80, p < 0.001; CKD-EPI: r = 0.87, p < 0.001; modification of diet in renal disease (MDRD): r = 0.84, p < 0.001; inulin clearance-based: r = 0.99, p < 0.001). Multivariable analysis demonstrated that decreased renal function is an independent predictor of 3-year mortality in all five formulas, with risk increasing by 15–25% for each 10-unit decrease in eGFR. Despite the similarities between the formulas, the ability to predict mortality was highest in the Mayo formula and lowest in MDRD.

Conclusions

Our data suggest that while the Mayo formula is not currently recommended by any nephrology guidelines, it may be an alternative formula to predict mortality among patients with multivessel CAD, including to the widely used MDRD formula.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13019-021-01502-1.

Renal functional impairment in the elderly, the importance of fasting plasma glucose: the Northern Shanghai Study

BACKGROUND

Chronic kidney disease is a global health problem that is closely related to the aging population. Although plasma glucose levels have been shown to be related to renal dysfunction, risk factors for renal functional impairment in the geriatric population are unknown. The authors therefore aimed to investigate the determinants of renal functional impairment in an elderly population.

METHODS

From June 2014 to August 2015, 912 participants (aged > 65 years) were recruited. Renal function was assessed at baseline; follow-up was conducted in 2016. Within the framework of comprehensive cardiovascular examinations, all conventional cardiovascular risk factors, fasting plasma glucose (FPG), and renal function were assessed. Renal function was evaluated by the estimated glomerular filtration rate (e-GFR) using a modified Modification of Diet in Renal Disease formula. Rapid decline in e-GFR was defined as an e-GFR slope > 5 mL/min per 1.73 m² per year.

RESULTS

We observed that FPG levels were significantly higher in participants with (6.15 ± 2.76 mmol/L) than in those without (5.56 ± 1.61 mmol/L) a rapid decline in e-GFR (p = 0.02). The average decline in e-GFR was 0.149 mL/min/1.73m² per year in this elderly population, and the increasing risk of having rapid decline in e-GFR was 0.44-fold each year. In the full adjustment model, decline in e-GFR (p = 0.02) and rapid decline in e-GFR (OR1.33, 95% CI 1.03-1.72) were significantly associated with FPG, independent of other conventional cardiovascular risk factors. Using the same models, decline in e-GFR (p = 0.04) and rapid decline in e-GFR (OR 1.57, 95% CI 1.05-2.35) were also significantly associated with FPG in diabetic population, but they were not in non-diabetic population.

CONCLUSIONS

In community-dwelling elderly Chinese, the average decline in e-GFR was 0.149 mL/min/1.73m² per year. FPG control is important for delaying renal functional impairment in elderly population. Trial registration NSS, NCT02368938.

Evaluation of Residual Kidney Function during Once-Weekly Incremental Hemodialysis

BACKGROUND

The initial once-weekly administration of incremental hemodialysis to patients with residual kidney function (RKF) has recently attracted considerable interest.

METHODS

The aim of our study was to assess the performance of a series of different methods in measuring serum urea nitrogen and serum Cr (sCr) RKF in patients on once-weekly hemodialysis (1WHD). Evaluations were carried out by means of 24-h predialysis urine collection (Kr-24H) or 6-day inter-dialysis collection (Kr-IDI) and estimation of glomerular filtration rate based on (KrSUN + KrsCr)/2 for the purpose of identifying a simple reference calculation to be used in assessing RKF in patients on 1WHD dialysis. Ninety-five urine samples were collected from 12 1WHD patients. A solute solver urea and Cr kinetic modeling program was used to calculate residual urea and Cr clearances. Mann-Whitney U test, Pearson's correlation coefficient (R), and linear determination coefficient (R2) were used for statistical analysis.

RESULTS

1WHD patients displayed a mean KrSUN-IDI of 4.5 ± 1.2 mL/min, while KrSUN-24H corresponded to 4.1 ± 0.9 mL/min, mean KrsCr-IDI to 9.1 ± 4.0 mL/min, and KrsCr 24H to 8.9 ± 4.2 mL/min, with a high regression between IDI and 24-h clearances (for IDI had R2 = 0.9149 and for 24H had R2 = 0.9595). A good correlation was also observed between KrSUN-24H and (KrSUN + KrsCR/2) (R2 = 0.7466, p < 0.01.

DISCUSSION

Urine collection over a 24-h predialysis period yielded similar results for both KrSUN and KrsCr compared to collection over a longer interdialytic interval (KrSUN + KrsCr)/2 could be applied to reliably assess RKF in patients on 1WHD.

CONCLUSION

The parameters evaluated are suitable for use as a routine daily method indicating the commencement and continued use of the 1WHD Incremental Program.

Global, regional, and national burden of chronic kidney disease, 1990-2017: a systematic analysis for the Global Burden of Disease Study 2017

BACKGROUND

Health system planning requires careful assessment of chronic kidney disease (CKD) epidemiology, but data for morbidity and mortality of this disease are scarce or non-existent in many countries. We estimated the global, regional, and national burden of CKD, as well as the burden of cardiovascular disease and gout attributable to impaired kidney function, for the Global Burden of Diseases, Injuries, and Risk Factors Study 2017. We use the term CKD to refer to the morbidity and mortality that can be directly attributed to all stages of CKD, and we use the term impaired kidney function to refer to the additional risk of CKD from cardiovascular disease and gout.

METHODS

The main data sources we used were published literature, vital registration systems, end-stage kidney disease registries, and household surveys. Estimates of CKD burden were produced using a Cause of Death Ensemble model and a Bayesian meta-regression analytical tool, and included incidence, prevalence, years lived with disability, mortality, years of life lost, and disability-adjusted life-years (DALYs). A comparative risk assessment approach was used to estimate the proportion of cardiovascular diseases and gout burden attributable to impaired kidney function.

FINDINGS

Globally, in 2017, 1·2 million (95% uncertainty interval [UI] 1·2 to 1·3) people died from CKD. The global all-age mortality rate from CKD increased 41·5% (95% UI 35·2 to 46·5) between 1990 and 2017, although there was no significant change in the age-standardised mortality rate (2·8%, -1·5 to 6·3). In 2017, 697·5 million (95% UI 649·2 to 752·0) cases of all-stage CKD were recorded, for a global prevalence of 9·1% (8·5 to 9·8). The global all-age prevalence of CKD increased 29·3% (95% UI 26·4 to 32·6) since 1990, whereas the age-standardised prevalence remained stable (1·2%, -1·1 to 3·5). CKD resulted in 35·8 million (95% UI 33·7 to 38·0) DALYs in 2017, with diabetic nephropathy accounting for almost a third of DALYs. Most of the burden of CKD was concentrated in the three lowest quintiles of Socio-demographic Index (SDI). In several regions, particularly Oceania, sub-Saharan Africa, and Latin America, the burden of CKD was much higher than expected for the level of development, whereas the disease burden in western, eastern, and central sub-Saharan Africa, east Asia, south Asia, central and eastern Europe, Australasia, and western Europe was lower than expected. 1·4 million (95% UI 1·2 to 1·6) cardiovascular disease-related deaths and 25·3 million (22·2 to 28·9) cardiovascular disease DALYs were attributable to impaired kidney function.

INTERPRETATION

Kidney disease has a major effect on global health, both as a direct cause of global morbidity and mortality and as an important risk factor for cardiovascular disease. CKD is largely preventable and treatable and deserves greater attention in global health policy decision making, particularly in locations with low and middle SDI.

FUNDING

Bill & Melinda Gates Foundation.

Biological variation of cardiac troponins in chronic kidney disease

Background

Patients with chronic kidney disease often have increased plasma cardiac troponin concentration in the absence of myocardial infarction. Incidence of myocardial infarction is high in this population, and diagnosis, particularly of non ST-segment elevation myocardial infarction (NSTEMI), is challenging. Knowledge of biological variation aids understanding of serial cardiac troponin measurements and could improve interpretation in clinical practice. The National Academy of Clinical Biochemistry (NACB) recommended the use of a 20% reference change value in patients with kidney failure. The aim of this study was to calculate the biological variation of cardiac troponin I and cardiac troponin T in patients with moderate chronic kidney disease (glomerular filtration rate [GFR] 30–59 mL/min/1.73 m2).

Methods and results

Plasma samples were obtained from 20 patients (median GFR 43.0 mL/min/1.73 m2) once a week for four consecutive weeks. Cardiac troponin I (Abbott ARCHITECT® i2000SR, median 4.3 ng/L, upper 99th percentile of reference population 26.2 ng/L) and cardiac troponin T (Roche Cobas® e601, median 11.8 ng/L, upper 99th percentile of reference population 14 ng/L) were measured in duplicate using high-sensitivity assays. After outlier removal and log transformation, 18 patients’ data were subject to ANOVA, and within-subject (CVI), between-subject (CVG) and analytical (CVA) variation calculated. Variation for cardiac troponin I was 15.0%, 105.6%, 8.3%, respectively, and for cardiac troponin T 7.4%, 78.4%, 3.1%, respectively. Reference change values for increasing and decreasing troponin concentrations were +60%/–38% for cardiac troponin I and +25%/–20% for cardiac troponin T.

Conclusions

The observed reference change value for cardiac troponin T is broadly compatible with the NACB recommendation, but for cardiac troponin I, larger changes are required to define significant change. The incorporation of separate RCVs for cardiac troponin I and cardiac troponin T, and separate RCVs for rising and falling concentrations of cardiac troponin, should be considered when developing guidance for interpretation of sequential cardiac troponin measurements.

Analgesic drug use in elderly persons: A population-based study in Southern Italy

INTRODUCTION

Analgesics such as non-steroidal anti-inflammatory drugs (NSAIDs), weak and strong opioids are commonly used among elderly persons. The aim of this study was to describe the demographic and clinical characteristics of elderly analgesic users and to measure the frequency of analgesic use, including the frequency of potentially inappropriate analgesic use.

METHODS

The Arianna database was used to carry out this study. This database contains prescription data with associated indication of use for 1,076,486 inhabitants registered with their general practitioners (GPs) in the Caserta Local Health Unit (Caserta district, Campania region in Italy). A cohort of persons aged ≥65 years old with >1 year of database history having at least one analgesic drug (NSAIDs, strong or weak opioids) between 2010 and 2014 were identified. The date of the first analgesic prescription in the study period was considered the index date (ID).

RESULTS

From a source population of 1,076,486 persons, 116,486 elderly persons were identified. Of these, 94,820 elderly persons received at least one analgesic drug: 36.6% were incident NSAID users (N = 36,629), while 13.2% were incident weak opioid users (N = 12,485) and 8.1% were incident strong opioid users (N = 7,658). In terms of inappropriate analgesic use, 9.2% (N = 10,763) of all elderly users were prescribed ketorolac/indomethacin inappropriately, since these drugs should not be prescribed to elderly persons. Furthermore, at least half all elderly persons with chronic kidney disease or congestive heart failure were prescribed NSAIDs, while these drugs should be avoided.

CONCLUSION

Analgesics are commonly used inappropriately among elderly persons, suggesting that prescribing practice in the catchment area may yet be improved.

Estimating GFR by Serum Creatinine, Cystatin C, and β2-Microglobulin in Older Adults: Results From the Canadian Study of Longevity in Type 1 Diabetes

INTRODUCTION

Glomerular filtration rate (GFR) is routinely used for clinical assessment of kidney function. However, the accuracy of estimating equations in older adults is uncertain.

METHODS

In 66 adults with ≥50 years type 1 diabetes (T1D) duration and 73 nondiabetic controls from age/sex-matched subgroups (65 ± 8 years old and 77[55%] were women) we evaluated the performance of estimated GFR (eGFR) by creatinine (Modification of Diet and Renal Disease [MDRD], Chronic Kidney Disease-Epidemiology [CKD-EPI]cr), cystatin C (CKD-EPIcys, CKD-EPIcr-cys), and β2-microglobulin (β2M) compared with measured GFR by inulin clearance (mGFR). Performance was evaluated using metrics of bias (mean difference), precision (SD), and accuracy (proportion of eGFR that differed by >20% of mGFR).

RESULTS

Mean mGFR was 104 ± 18 ml/min per 1.73 m2 (range: 70-154 ml/min per 1.73 m2) and was not different between T1D and controls (103 ± 17 vs. 105 ± 19 ml/min per 1.73 m2, P = 0.39). All equations significantly underestimated mGFR (bias: -15 to -30 ml/min per 1.73 m2, P < 0.001 for all comparisons) except for β2M, which had bias of 1.9 ml/min per 1.73 m2 (P = 0.61). Bias was greatest in cystatin C-based equations. Precision was lowest for β2M (SD: 43.5 ml/min per 1.73 m2, P < 0.001 for each comparison). Accuracy was lowest for CKD-EPIcysC (69.1%, P < 0.001 for each comparison). Cystatin C-based equations demonstrated greater bias and lower accuracy in older age subgroups (<60, 60-69, ≥70 years). All equations demonstrated greater bias across higher ranges of mGFR (60-89, 90-119, ≥120 ml/min per 1.73 m2). Results were similar between T1D and controls except that β2M had lower performance in T1D.

CONCLUSION

Better estimates of GFR in older adults are needed for research and clinical practice, as this subgroup of the population has an amplified risk for the development of chronic kidney disease (CKD) that requires accurate GFR estimation methods.

Clinical factors increasing discrepancies of renal function assessment with MDRD and Cockcroft-Gault equations in old individuals

ABSTRACT

In a daily clinical practice, glomerular filtration rate (GFR) is still estimated on the basis of short MDRD formula, whereas medications' Summaries of Product Characteristics suggest that GFR used for the dosage adjustment should be estimated based on the Cockcroft-Gault (C-G) equation. The aim of the study was to compare eGFR values calculated on the basis of short and full MDRD and C-G equations in PolSenior study participants with decreased eGFR.

METHODS

We have assessed differences in the estimation of GFR between short and full MDRD, as well as C-G formula, all equations utilizing non-isotope-dilution mass spectrometry-calibrated measurements of serum creatinine, in the community-based population of 760 persons aged 65 years or above (mean age 82 ± 8 years) with estimated GFR < 60 ml/min/1.73 m2 (according to short MDRD). In addition, in our analysis, we have included the detailed characteristics of comorbidities and different aspects of mobility and functional performance.

RESULTS

The better concordance, precision, and accuracy with MDRD short formula were found for MDRDfull than C-G equation. In logistic regression analysis, female gender, activities in daily living (ADL) ≤ 4, and age > 80 years diminished, while visceral obesity improved accuracy (P30) of eGFR calculated according to C-G equation as compared to MDRDshort. Similar analysis did not found factors influencing P30 for MDRDfull equation.

CONCLUSIONS

In very old subjects, especially females, dependent patients and those with visceral obesity, estimation of GFR based on short MDRD formula should not be used interchangeably with Cockcroft-Gault equation for the medicines dose tailoring.

Disparities in the Estimation of Glomerular Filtration Rate According to Cockcroft-Gault, Modification of Diet in Renal Disease-4, and Chronic Kidney Disease Epidemiology Collaboration Equations and Relation With Outcomes in Patients With Acute Coronary Syndrome

BACKGROUND

A simple method to assess renal function is the estimated glomerular filtration rate, and it shows prognostic implications. However, it remains unknown which equation should be used in patients with acute coronary syndrome. We compared the ability and correlation of the Cockcroft-Gault, Modification of Diet in Renal Disease-4 (MDRD-4), and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations and their predictive performance for major adverse cardiovascular events, all-cause mortality, and major bleeding in a cohort of patients with acute coronary syndrome.

METHODS AND RESULTS

Multicenter prospective registry involving 1699 consecutive patients with acute coronary syndrome from 3 tertiary institutions. At entry, renal function was assessed using the Cockcroft-Gault, MDRD-4, and CKD-EPI-creatinine equations. During 12 months of follow-up, we recorded all major adverse cardiovascular events (composite of cardiovascular death, nonfatal myocardial infarction, and nonfatal ischemic stroke), bleeding events (Bleeding Academic Research Consortium classification), and all-cause mortality. Receiver operating characteristic curve comparisons demonstrated that Cockcroft-Gault equation had higher predictive ability compared with MDRD-4 equation for major adverse cardiovascular events (0.651 versus 0.616; P=0.023), major bleeding (0.600 versus 0.551; P=0.005), and all-cause mortality (0.754 versus 0.717; P=0.033), as well as higher predictive ability compared with CKD-EPI equation for major bleeding (0.600 versus 0.564; P=0.018). Integrated discrimination improvement and net reclassification improvement analyses showed superior discrimination and reclassification of Cockcroft-Gault equation. Decision curve analyses graphically demonstrated higher net benefit and clinical usefulness of the Cockcroft-Gault equation in comparison with MDRD-4 and CKD-EPI equations.

CONCLUSIONS

In patients with acute coronary syndrome, the Cockcroft-Gault equation presented superior predictive ability for major adverse cardiovascular events, major bleeding, and all-cause mortality compared with MDRD-4 equation, and superior predictive ability for major bleeding compared with CKD-EPI equation. The Cockcroft-Gault equation also showed higher net benefit and clinical usefulness.

Aging and decreased glomerular filtration rate: An elderly population-based study

BACKGROUND

Although a reduced glomerular filtration rate (GFR) in old people has been attributed to physiologic aging, it may be associated with kidney disease or superimposed comorbidities. This study aims to assess the prevalence of decreased GFR in a geriatric population in a developing country and its prevalence in the absence of simultaneous diseases.

STUDY DESIGN AND METHODS

This is a cross-sectional study of data from the Saúde, Bem-Estar e Envelhecimento cohort study (SABE study[Health, Well-Being and Aging]), a multiple cohorts study. A multistage cluster sample composed of 1,253 individuals representative of 1,249,388 inhabitants of São Paulo city aged ≥60 years in 2010 was analyzed. The participants answered a survey on socio-demographic factors and health, had blood pressure measured and urine and blood samples collected. GFR was estimated and defined as decreased when <60 mL/min/1.73m2. Kidney damage was defined as dipstick-positive hematuria or urinary protein:creatinine > 0.20 g/g.

RESULTS

The prevalence of GFR <60 mL/min/1.73m2 was 19.3%. Individuals with GFR <60 mL/min/1.73m2 were older (75±1 versus 69±1 years, p<0.001), had lower schooling (18 versus 30% with complete 8-year basic cycle, p = 0.010), and higher prevalence of hypertension (82 versus 63%, p<0.001), diabetes (34 versus 26%, p = 0.021), cardiovascular disease (43 versus 24%, p<0.001) and kidney damage (35% versus 15%, p<0.001). Only 0.7% of the entire studied population had GFR <60 mL/min/1.73m2 without simultaneous diseases or kidney damage. Among the individuals with GFR <60 mL/min/1.73m2, 3.5% had neither renal damage nor associated comorbidities, whereas among those with GFR ≥60 mL/min/1.73m2, 11.0% had none of these conditions. Logistic regression showed that older age, cardiovascular disease and hypertension were associated with GFR<60 mL/min/1.73m2.

CONCLUSIONS

Decreased GFR was highly prevalent among the geriatric population in a megalopolis of a developing country. It was rarely present without simultaneous chronic comorbidities or kidney damage.

Comparison of MDRD, CKD-EPI, and Cockcroft-Gault equation in relation to measured glomerular filtration rate among a large cohort with diabetes

AIMS

To analyze the performance of Modification of Diet in Renal Disease (MDRD), Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI), Cockcroft-Gault (CG), and CG calculated with ideal bodyweight (CG-IBW) equations to estimate glomerular filtration rate (eGFR) based on serum creatinine in a large diabetic population.

METHODS

24,516 adults with type-1-diabetes or type-2-diabetes from the multicenter diabetes prospective follow-up registry DPV were analyzed. We compared eGFR and measured GFR (mGFR) based on 24-h urine collection by calculating mean bias (difference), precision (SD of this difference), accuracy (proportion of eGFR within ±10% of mGFR), Bland-Altman-plots.

RESULTS

CG overestimates, whereas MDRD, CKD-EPI, and CG-IBW underestimate. Smallest mean bias and highest accuracy (75.3%) were observed for MDRD compared to the other equations (p<0.0001). MDRD and CKD-EPI estimated most accurately in stages 1 (MDRD:57.7%, CKD-EPI:57.3%) and 2 (MDRD:80.2%, CKD-EPI:80.7%). In stages 3 to 5, highest accuracy was observed for the MDRD (stage 3:82.3%, stage 4:77.8%, stage 5:71.0%). Among younger subjects, accuracy was higher using the CKD-EPI (18-<40years:63.7%, 40-<60years:72.8%). Above age 60years, MDRD estimated most accurately (60-<70years:77.3%, ≥70years:78.8%). In males and females, MDRD estimated most accurately (males:75.3%, females:75.3%).

CONCLUSION

In this large diabetic cohort, smallest bias and highest accuracy were observed for the MDRD.

An external validation of models to predict the onset of chronic kidney disease using population-based electronic health records from Salford, UK

BACKGROUND

Chronic kidney disease (CKD) is a major and increasing constituent of disease burdens worldwide. Early identification of patients at increased risk of developing CKD can guide interventions to slow disease progression, initiate timely referral to appropriate kidney care services, and support targeting of care resources. Risk prediction models can extend laboratory-based CKD screening to earlier stages of disease; however, to date, only a few of them have been externally validated or directly compared outside development populations. Our objective was to validate published CKD prediction models applicable in primary care.

METHODS

We synthesised two recent systematic reviews of CKD risk prediction models and externally validated selected models for a 5-year horizon of disease onset. We used linked, anonymised, structured (coded) primary and secondary care data from patients resident in Salford (population ~234 k), UK. All adult patients with at least one record in 2009 were followed-up until the end of 2014, death, or CKD onset (n = 178,399). CKD onset was defined as repeated impaired eGFR measures over a period of at least 3 months, or physician diagnosis of CKD Stage 3-5. For each model, we assessed discrimination, calibration, and decision curve analysis.

RESULTS

Seven relevant CKD risk prediction models were identified. Five models also had an associated simplified scoring system. All models discriminated well between patients developing CKD or not, with c-statistics around 0.90. Most of the models were poorly calibrated to our population, substantially over-predicting risk. The two models that did not require recalibration were also the ones that had the best performance in the decision curve analysis.

CONCLUSIONS

Included CKD prediction models showed good discriminative ability but over-predicted the actual 5-year CKD risk in English primary care patients. QKidney, the only UK-developed model, outperformed the others. Clinical prediction models should be (re)calibrated for their intended uses.

Polymorphisms associated with renal adverse effects of antiretroviral therapy in a Southern Brazilian HIV cohort

OBJECTIVE

This study evaluated the impact of seven single nucleotide polymorphisms in five candidate genes (ABCB1, ABCC2, ABCC4, SLC22A6, and SLC22A11) in relation to nephrotoxicity associated with highly active antiretroviral therapy (HAART) in HIV-infected individuals.

METHODS

The following single nucleotide polymorphisms were genotyped by real-time PCR: ABCB1 rs1045642, ABCC2 rs717620 and rs2273697, ABCC4 rs1751034 and rs3742106, SLC22A6 rs11568626, and SLC22A11 rs11231809 in 507 HIV-infected patients from the city of Porto Alegre, Southern Brazil, receiving HAART for, at least, 1 year.

RESULTS

From the 507 HIV-infected patients recruited, 19.1% presented a reduction in estimated glomerular filtration rate (eGFR). A total of 16 (3.2%) patients fulfilled the criteria for chronic kidney disease (defined as eGFR<60 ml/min/1.73 m). Individuals carrying at least one T allele of ABCC2 -24 C>T (rs717620) presented lower eGFR than C/C homozygotes (104 ± 22 vs. 108 ± 22 ml/min/1.73 m, independent-samples t-test, P=0.040). In multivariate analysis, the predictors associated with decreased eGFR were time of treatment, tenofovir use, atazanavir/ritonavir use, and carrying one T allele of ABCC2 -24 C>T.

CONCLUSION

Our data support the importance of genetic factors in the etiology of nephrotoxicity in patients treated with HAART. Studies to verify treatment implications of genotyping before HAART initiation may be advisable to guide the selection of an appropriate antiretroviral therapy regimen.

Prognostic Value of Renal Dysfunction Indicators in Normotensive Patients With Acute Pulmonary Embolism

Introduction:

Glomerular filtration rate (GFR) and blood urea nitrogen (BUN) are important prognostic indicators for cardiovascular disease. However, data on the relationship between renal dysfunction (RD) and prognosis in patients with acute pulmonary embolism (APE) are limited. The estimated-GFR (eGFR), based on the Modification of Diet in Renal Disease (MDRD) equation, has been suggested as a possible prognostic marker in patients with APE; however, at present, the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation is thought to be more accurate than the MDRD equation for the estimation of RD.

Objective:

We investigated whether eGFRCKD-EPI or BUN could predict adverse outcomes (AOs) better than eGFRMDRD in normotensive patients with APE.

Methods:

Ninety-nine normotensive patients with APE (aged 22-96, 56% male) were enrolled in the study retrospectively. Adverse outcomes were defined as the occurrence of any of the following: death, cardiopulmonary resuscitation, use of vasopressors, thrombolysis, or mechanical ventilation.

Results:

In univariate analyses, age, gender (male), heart rate (>110 bpm), serum creatinine, BUN, cardiac troponin (cTn) positivity, right ventricle–left ventricle ratio, eGFRMDRD, and eGFRCKD-EPI were found to be significantly different between those with and without AOs. Comparing area under the curves for AO, we found statistically significant differences between eGFRCKD-EPI and eGFRMDRD ( P = .01) but not between BUN and eGFRCKD-EPI or BUN and eGFRMDRD. Furthermore, 30-day mortality was 36% versus 11% in cTn-positive patients with an eGFRCKD-EPI < and ≥ 60 mL/min, respectively.

Conclusion:

There is a close relationship between RD and APE prognosis. We conclude eGFRCKD-EPI is a potential prognostic marker for risk stratification in normotensive patients with APE.

Accuracy and precision of the CKD-EPI and MDRD predictive equations compared with glomerular filtration rate measured by inulin clearance in a Saudi population

BACKGROUND

Predictive equations for estimating glomerular filtration rate (GFR) in different clinical conditions should be validated by comparing with the measurement of GFR using inulin clearance, a highly accurate measure of GFR.

OBJECTIVES

Our aim was to validate the Chronic Kidney Disease-Epidemiology Collaboration (CKD-EPI) and Modification of Diet in Renal Disease (MDRD) equations by comparing it to the GFR measured using inulin clearance in chronic kidney disease (CKD) patients.

DESIGN

Cross-sectional study performed in adult Saudi patients with CKD.

SETTING

King Saud University Affiliated Hospital, Riyadh, Saudi Arabia in 2014.

PATIENTS AND METHODS

We compared GFR measured by inulin clearance with the estimated GFR calculated using CKD-EPI and MDRD predictive formulas.

MAIN OUTCOME MEASURE(S)

Correlation, bias, precision and accuracy between the estimated GFR and inulin clearance.

RESULTS

Comparisons were made in 31 participants (23 CKD and 8 transplanted), including 19 males (mean age 42.2 [15] years and weight 68.7 [18] kg). GFR using inulin was 51.54 (33.8) mL/min/1.73 m2 in comparison to inulin clearance, the GFR by the predictive equations was: CKD-EPI creatinine 52.6 (34.4) mL/ min/1.73 m2 (P=.490), CKD-EPI cystatin C 41.39 (30.30) mL/min/1.73 m2 (P=.002), CKD creatinine-cystatin C 45.03 (30.9) mL/min/1.73 m2 (P=.004) and MDRD GFR 48.35 (31.5) mL/min/1.73 m2 (P=.028) (statistical comparisons vs inulin). Bland-Altman plots demonstrated that GFR estimated by the CKD-EPI creatinine was the most accurate compared with inulin clearance, having a mean difference (estimated bias) and limits of agreement of -1.1 (15.6,-17.7). By comparison the mean differences for predictive equations were: CKD-EPI cystatin C 10.2 (43.7,-23.4), CKD creatinine-cystatin C 6.5 (29.3,-16.3) and MDRD 3.2 (18.3,-11.9). except for CKD-EPI creatinine, all of the equations underestimated GFR in comparison with inulin clearance.

CONCLUSIONS

When compared with inulin clearance, the CKD-EPI creatinine equation is the most accurate, precise and least biased equation for estimation of GFR in the Saudi population and in all subgroups by age, stage of CKD and transplantation status.

LIMITATIONS

Small sample size and the study did not include patients with comorbid diseases such as diabetes, hepatitis C virus infection, and other co-morbidities as well as old age ( > 80 years).

Cardiovascular and all-cause mortality in patients with type 2 diabetes mellitus in the MADIABETES Cohort Study: Association with chronic kidney disease

AIMS

To assess the prevalence of stage 3-5 chronic kidney disease (CKD) at baseline and to identify associated risk factors. To determine the effect of CKD and CKD stage according to estimated glomerular filtration rate (eGFR) and albuminuria categories on all-cause and cardiovascular mortality after a 5-year follow-up.

METHODS

Prospective cohort study of 3443 outpatients with type 2 diabetes mellitus.

RESULTS

The prevalence of CKD was 28.32% (95% CI, 26.84-29.86); and variables most strongly associated were: age >74 years (OR, 19.88; 95% CI, 12.89-30.68) and albuminuria (OR, 2.27; 95% CI, 1.72-3.00). During follow-up, 221 CKD patients (22.90%) died compared with 203 non-CKD patients (8.31%) (p<0.01). The adjusted HR of CKD for cardiovascular and all-cause mortality was 1.82 (95% CI, 1.36-2.44) and 2.11 (95% CI, 1.61-2.76) for those with LDL cholesterol =135 mg/dl, respectively. The adjusted HR of very-high-risk CKD for all-cause mortality was 4.44 (95% CI, 2.31-8.53) in aged <75 years and 1.80 (95% CI, 1.19-2.72) in aged ≥75 years.

CONCLUSIONS

CKD at baseline is an independent risk factor for all-cause and cardiovascular mortality in the overall cohort, men and women, or in primary and secondary prevention of coronary heart disease. Albuminuria is an independent risk factor for all-cause and cardiovascular mortality only in primary prevention.

Impact of routine reporting of estimated glomerular filtration rate using the CKD-EPI formula in a community population: A cross-sectional cohort study

AIM

Most laboratories are moving to report estimated glomerular filtration rates (eGFR) using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) formula. However, data on the prevalence of chronic kidney disease (CKD) in the population and its economic impact have to date been modelled using data derived from the modification of diet in renal disease (MDRD) equation. Evaluating the impact of CKD-EPI on prevalence has important implications for referral patterns and health expenditure.

METHODS

eGFR were calculated from 2 295313 creatinine results from 833334 patients using the MDRD and CKD-EPI formulae. The proportion of patients in each CKD stage was determined and annual rates of change of eGFR in patients assigned to a new CKD stage compared with their previous CKD stage calculated. The effects of age on eGFR were assessed.

RESULTS

Reporting of eGFR using the CKD-EPI equation reduced the prevalence of CKD stages III-V from 9.2% to 7.6%. A total of 181126 patients were reclassified using CKD-EPI with 171298 changing to a better CKD stage. Reclassification rates were highest in CKD stages II and III. Patients reclassified from stage III to II tended to be younger or female. eGFR declines rapidly after the age of 60.

CONCLUSIONS

Introduction of routine eGFR reporting using the CKD-EPI formula will reduce the population prevalence of CKD. CKD-EPI reporting better identifies patients at risk of further decline in renal function. Improvement in the classification should reduce unnecessary costs related to surveillance and referral. The impact of ageing on renal function should be appreciated.

Comparison of predictive performance of renal function estimation equations for all-cause and cardiovascular mortality in an elderly hypertensive population

BACKGROUND

The Modifications of Diet in Renal Disease (MDRD) and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) are 2 equations commonly used to estimate glomerular filtration rate (eGFR). The predictive performance offered by these equations, particularly in relation to clinical outcomes in elderly hypertensive patients, is not clear.

METHODS

The Second Australian National Blood Pressure Study cohort was used to investigate the predictive performance of these 2 equations for long-term outcomes (median 10.8 years) in elderly treated hypertensive patients. Both equations were used to calculate eGFR in 6,083 patients aged ≥65 years and classified as having chronic kidney disease (CKD) or no CKD (eGFR ≥60ml/min/1.73 m2).

RESULTS

More patients were classified as having no CKD using the CKD-EPI equation compared with the MDRD equation (72.1% vs. 69.4%; P = 0.001). Both equations performed similarly in risk prediction of all-cause and cardiovascular mortality with decreased eGFR, except for patients with baseline eGFR of 45-59ml/min/1.73 m2, where the CKD-EPI equation predicted higher risk of all-cause mortality compared with those with no CKD. However, the magnitude of difference in risk prediction was too small to be clinically meaningful. Both equations showed similar predictive performance. However, we observed longer survival and no higher risk in those who were reclassified as having no CKD using the CKD-EPI equation, but these patients were classified earlier as having CKD using the MDRD equation.

CONCLUSIONS

There was no clinically relevant difference in predictive performance for long-term survival by eGFR calculated using either of these equations in this elderly hypertensive population.

Comparing GFR Estimating Equations Using Cystatin C and Creatinine in Elderly Individuals

Current guidelines recommend reporting eGFR using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations unless other equations are more accurate, and recommend the combination of creatinine and cystatin C (eGFRcr-cys) as more accurate than either eGFRcr or eGFRcys alone. However, preferred equations and filtration markers in elderly individuals are debated. In 805 adults enrolled in the community-based Age, Gene/Environment Susceptibility (AGES)-Reykjavik Study, we measured GFR (mGFR) using plasma clearance of iohexol, standardized creatinine and cystatin C, and eGFR using the CKD-EPI, Japanese, Berlin Initiative Study (BIS), and Caucasian and Asian pediatric and adult subjects (CAPA) equations. We evaluated equation performance using bias, precision, and two measures of accuracy. We first compared the Japanese, BIS, and CAPA equations with the CKD-EPI equations to determine the preferred equations, and then compared eGFRcr and eGFRcys with eGFRcr-cys using the preferred equations. Mean (SD) age was 80.3 (4.0) years. Median (25th, 75th) mGFR was 64 (52, 73) ml/min per 1.73 m(2), and the prevalence of decreased GFR was 39% (95% confidence interval, 35.8 to 42.5). Among 24 comparisons with the other equations, CKD-EPI equations performed better in 9, similar in 13, and worse in 2. Using the CKD-EPI equations, eGFRcr-cys performed better than eGFRcr in four metrics, better than eGFRcys in two metrics, and similar to eGFRcys in two metrics. In conclusion, neither the Japanese, BIS, nor CAPA equations were superior to the CKD-EPI equations in this cohort of community-dwelling elderly individuals. Using the CKD-EPI equations, eGFRcr-cys performed better than eGFRcr or eGFRcys.

Chronic kidney disease requiring healthcare services: a new approach to evaluate epidemiology of renal disease

BACKGROUND

Screening-based CKD estimates may not provide a sufficient insight into the impact of CKD on the use of healthcare resources in clinical practice. The aim of this study was to evaluate the epidemiology of "medicalized" CKD, that is, CKD requiring healthcare services, in an outpatient setting.

DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS

This is a retrospective, longitudinal population-based study conducted in a large general practice setting in Southern Italy (Caserta) using a healthcare database. Over 2006-2011, all patients with a CKD diagnosis, either through CKD-related indications of use associated with drug prescriptions or through CKD-related hospital discharge diagnoses/procedures, were identified using this database. The prevalence of "medicalized" CKD in the general population of Caserta was estimated by age, gender, and calendar year.

RESULTS

Overall, 1,989 (1.3%) patients with a diagnosis of CKD were identified from 2006-2011 in the Caserta general population. The one year prevalence increased from 0.9% in 2006 to 1.6% in 2011, which is much lower compared to previous screening-based studies. The prevalence was slightly higher in males and increased significantly with advancing age (in 2011, 0.2% in ≤44 years old versus 9.2% in >80 years old).

CONCLUSIONS

The findings of this study suggest that, in the general population, the prevalence of "medicalized" CKD is lower compared to the screening-based CKD prevalence.

Change in prevalence of chronic kidney disease in England over time: comparison of nationally representative cross-sectional surveys from 2003 to 2010

OBJECTIVES

To determine whether the prevalence of chronic kidney disease (CKD) in England has changed over time.

DESIGN

Cross-sectional analysis of nationally representative Health Survey for England (HSE) random samples.

SETTING

England 2003 and 2009/2010.

SURVEY PARTICIPANTS

13,896 adults aged 16+ participating in HSE, adjusted for sampling and non-response, 2009/2010 surveys combined.

MAIN OUTCOME MEASURE

Change in prevalence of estimated glomerular filtration rate (eGFR)<60 mL/min/1.73 m2 (as proxy for stage 3-5 CKD), from 2003 to 2009/2010 based on a single serum creatinine measure using an isotope dilution mass spectrometry traceable enzymatic assay in a single laboratory; eGFR derived using Modified Diet in Renal Disease (MDRD) and Chronic Kidney Disease Epidemiology Collaboration (CKDEPI) eGFR formulae.

ANALYSIS

Multivariate logistic regression modelling to adjust time changes for sociodemographic and clinical factors (body mass index, hypertension, diabetes, lipids). A correction factor was applied to the 2003 HSE serum creatinine to account for a storage effect.

RESULTS

National prevalence of low eGFR (<60) decreased within each age and gender group for both formulae except in men aged 65-74. Prevalence of obesity and diabetes increased in this period, while there was a decrease in hypertension. Adjustment for demographic and clinical factors led to a significant decrease in CKD between the surveyed periods. The fully adjusted OR for eGFR<60 mL/min/1.73 m2 was 0.75 (0.61 to 0.92) comparing 2009/2010 with 2003 using the MDRD equation, and was similar using the CKDEPI equation 0.73 (0.57 to 0.93).

CONCLUSIONS

The prevalence of a low eGFR indicative of CKD in England appeared to decrease over this 7-year period, despite the rising prevalence of obesity and diabetes, two key causes of CKD. Hypertension prevalence declined and blood pressure control improved but this did not appear to explain the fall. Periodic assessment of eGFR and albuminuria in future HSEs is needed to evaluate trends in CKD.

Application of creatinine- and/or cystatin C-based glomerular filtration rate estimation equations in elderly Chinese

Background

No conventional creatinine- or cystatin C-based glomerular filtration rate (GFR) estimation equation performed consistently outstandingly in elderly Chinese in our previous studies. This research aimed to further evaluate the performance of some recently proposed estimation equations based on creatinine and cystatin C, alone or combined, in this specific population.

Materials and methods

The equations were validated in a population totaling 419 participants (median age 68 [range 60–94] years). The estimated GFR (eGFR) calculated separately by ten equations was compared with the reference GFR (rGFR) measured by the ^99mTc-DTPA renal dynamic imaging method.

Results

Median serum creatinine, cystatin C, and rGFR levels were 0.93 mg/L, 1.13 mg/L, and 74.20 mL/min/1.73 m², respectively. The Chinese population-developed creatinine- and cystatin C-based (Cscr-cys) equation yielded the least median absolute difference (8.81 vs range 9.53–16.32, P<0.05, vs the Chronic Kidney Disease Epidemiology Collaboration serum creatinine equation), the highest proportion of eGFR within 15% and 30% of rGFR (P₁₅ and P₃₀, 55.13 and 85.44, P<0.05 and P<0.01, vs the Chronic Kidney Disease Epidemiology Collaboration serum creatinine equation), and the lowest root mean square error (14.87 vs range 15.30–22.45) in the whole cohort. A substantial agreement of diagnostic consistency between eGFR and rGFR (with a kappa 0.61–0.80) was also observed with the Cscr-cys equation. Moreover, measures of performance in the Cscr-cys equation were consistent across normal to mildly injured GFR strata and individuals aged ≤80 years. Among all the Cscr-cys equations, the elderly Chinese-developed creatinine-based (CEscr) equation performed best in this specific population. Nevertheless, none of the equations achieved ideal manifestation in the moderately to severely GFR-injured group or in individuals aged ≥80 years.

Conclusion

The Cscr-cys equation appeared to be optimal in elderly Chinese among the investigated equations. If cystatin C is not available, the CEscr equation is an acceptable alternative. A multicenter study with abundant subjects to develop an apposite formula for elderly Chinese is assumed to be essential.

The need for improved identification and accurate classification of stages 3-5 Chronic Kidney Disease in primary care: retrospective cohort study

Background

Around ten percent of the population have been reported as having Chronic Kidney Disease (CKD), which is associated with increased cardiovascular mortality. Few previous studies have ascertained the chronicity of CKD. In the UK, a payment for performance (P4P) initiative incentivizes CKD (stages 3–5) recognition and management in primary care, but the impact of this has not been assessed.

Methods and Findings

Using data from 426 primary care practices (population 2,707,130), the age standardised prevalence of stages 3–5 CKD was identified using two consecutive estimated Glomerular Filtration Rates (eGFRs) seven days apart. Additionally the accuracy of practice CKD registers and the relationship between accurate identification of CKD and the achievement of P4P indicators was determined. Between 2005 and 2009, the prevalence of stages 3–5 CKD increased from 0.3% to 3.9%. In 2009, 30,440 patients (1.1% unadjusted) fulfilled biochemical criteria for CKD but were not on a practice CKD register (uncoded CKD) and 60,705 patients (2.2% unadjusted) were included on a practice CKD register but did not fulfil biochemical criteria (miscoded CKD). For patients with confirmed CKD, inclusion in a practice register was associated with increasing age, male sex, diabetes, hypertension, cardiovascular disease and increasing CKD stage (p<0.0001). Uncoded CKD patients compared to miscoded patients were less likely to achieve performance indicators for blood pressure (OR 0.84, 95% CI 0.82–0.86 p<0.001) or recorded albumin-creatinine ratio (OR 0.73, 0.70–0.76, p<0.001).

Conclusions

The prevalence of stages 3–5 CKD, using two laboratory reported eGFRs, was lower than estimates from previous studies. Clinically significant discrepancies were identified between biochemically defined CKD and appearance on practice registers, with misclassification associated with sub-optimal care for some people with CKD.

A determination of the current causes of hyperkalaemia and whether they have changed over the past 25 years

OBJECTIVE

Hyperkalaemia is a potentially lethal electrolyte disorder. The objective of this study was to determine if the causes of hyperkalaemia-related visits to the emergency department (ED) have changed since 25 years.

METHODS

All patients presenting to the ED with hyperkalaemia between January 2009 and August 2011 were included in this retrospective, single-centre study. Patients were divided into one of these three categories: mild (5·2≤ K(+)<5·8 mEq/l), moderate (5·8≤K(+)<7·0 mEq/l) or severe hyperkalaemia (K(+)≥7·0 mEq/l). The causes of hyperkalaemia were divided into three groups: renal failure (RF), potassium-increasing drugs (PIDs) or others.

RESULTS

Overall, 139 patients with hyperkalaemia were included in the study (mean K(+) of 6·2 mEq/l): 35% with mild, 49% with moderate and 16% with severe hyperkalaemia. Eighty-three per cent of patients (n = 115) had RF with creatinine levels ≥1·25 mg/dl or estimated glomerular filtration rate (eGFR) levels ≤60 ml/min/1·73 m(2). Serum potassium levels were significantly related with creatinine and eGFR values (P<0·001). The severity of hyperkalaemia was significantly related with creatinine levels ≥1·25 mg/dl (P = 0·002) and eGFR values ≤60 ml/min/1·73 m(2) (P = 0·005). Seventy-five per cent of patients (n = 105) were taking PIDs. Potassium levels were significantly related with PIDs (P<0·001), in particularly spironolactone (P = 0·001) and angiotensin-converting enzyme inhibitors (P = 0·008). The category 'others' included 7% of patients (n = 10).

CONCLUSIONS

RF (83%) and PIDs (75%) remain common causes of hyperkalaemia. Hyperkalaemia is significantly related with four variables: creatinine levels, spironolactone, ACEIs and beta-blocker intake. The causes of hyperkalaemia have not changed in recent years.

Comparison between Three Different Equations for the Estimation of Glomerular Filtration Rate in Omani Patients with Type 2 Diabetes Mellitus

OBJECTIVES

Estimated glomerular filtration rate (eGFR) is an important component of a patient's renal function profile. The Modification of Diet in Renal Disease (MDRD) equation and the Chronic Kidney Disease-Epidemiology Collaboration (CKD-EPI) equation are both commonly used. The aim of this study was to compare the performance of the original MDRD186, revised MDRD175 and CKD-EPI equations in calculating eGFR in type 2 diabetes mellitus (T2DM) patients in Oman.

METHODS

The study included 607 T2DM patients (275 males and 332 females, mean age ± standard deviation 56 ± 12 years) who visited primary health centres in Muscat, Oman, during 2011 and whose renal function was assessed based on serum creatinine measurements. The eGFR was calculated using the three equations and the patients were classified based on chronic kidney disease (CKD) stages according to the National Kidney Foundation Kidney Disease Outcomes Quality Initiative guidelines. A performance comparison was undertaken using the weighted kappa test.

RESULTS

The median eGFR (mL/min/1.73 m(2)) was 92.9 for MDRD186, 87.4 for MDRD175 and 93.7 for CKD-EPI. The prevalence of CKD stage 1 was 55.4%, 44.7% and 57% while for stages 2 and 3 it was 43.2%, 54% and 41.8%, based on MDRD186, MDRD175 and CKD-EPI, respectively. The agreement between MDRD186 and CKD-EPI (к 0.868) was stronger than MDRD186 and MDRD175 (к 0.753) and MDRD175 and CKD-EPI (к 0.730).

CONCLUSION

The performances of MDRD186 and CKD-EPI were comparable. Considering that CKD-EPI-based eGFR is known to be close to isotopically measured GFR, the use of MDRD186 rather than MDRD175 may be recommended.

Drug dosing in elderly patients with chronic kidney disease

As the elderly population in the United States increases, health care professionals need to be aware of potential age-related changes that affect medication prescribing. Increased emphasis on careful patient assessment and safety can reduce the incidence of adverse events related to medications.

Combined application of eGFR and albuminuria for the precise diagnosis of stage 2 and 3a CKD in the elderly

BACKGROUND

Estimated glomerular filtration rate (eGFR) is the sole diagnostic criterion for stage 3a chronic kidney disease (CKD). Because eGFR decreases with age, its prognostic utility in the elderly is controversial. Albuminuria is an important prognostic factor. To confirm that eGFR use may lead to the overdiagnosis of CKD and to examine the utility of eGFR combined with albuminuria for diagnosing stage 3a CKD in the elderly.

METHODS

This study included 365 elderly patients (age ≥ 65 years) who were diagnosed with stage 2 or 3a CKD. All patients had 3 years of consecutive data at our hospitals from 2000 to 2012. For each eGFR level, patients were divided into normalbuminuria (NOR, urinary albumin excretion rate [UAER] < 30 mg/24 h), microalbuminuria (30 ≥ UAER < 299 mg/24 h), and macroalbuminuria groups (UAER ≥ 300 mg/24 h).

RESULTS

Albuminuria was associated with eGFR loss but not baseline eGFR level. When stage 2 NOR was used as a reference, the multivariable adjusted odds ratio (OR) for rapid kidney function decline (RKFD) of stage 3a NOR was 1.329 (95 % confidence interval (CI): 0.334-5.281, P = 0.686). ORs for other groups were significantly higher. In stage 3a NOR, higher ORs for RKFD were associated with younger age groups.

CONCLUSIONS

Lot of elderly patients with stage 3a CKD and normal albuminuria levels may be over-diagnosed. Albuminuria may be combined with eGFR for improved diagnosis and treatment of stage 3 CKD in the elderly.

The eGFR-C study: accuracy of glomerular filtration rate (GFR) estimation using creatinine and cystatin C and albuminuria for monitoring disease progression in patients with stage 3 chronic kidney disease--prospective longitudinal study in a multiethnic population

BACKGROUND

Uncertainty exists regarding the optimal method to estimate glomerular filtration rate (GFR) for disease detection and monitoring. Widely used GFR estimates have not been validated in British ethnic minority populations.

METHODS/DESIGN

Iohexol measured GFR will be the reference against which each estimating equation will be compared. The estimating equations will be based upon serum creatinine and/or cystatin C. The eGFR-C study has 5 components: 1) A prospective longitudinal cohort study of 1300 adults with stage 3 chronic kidney disease followed for 3 years with reference (measured) GFR and test (estimated GFR [eGFR] and urinary albumin-to-creatinine ratio) measurements at baseline and 3 years. Test measurements will also be undertaken every 6 months. The study population will include a representative sample of South-Asians and African-Caribbeans. People with diabetes and proteinuria (ACR ≥30 mg/mmol) will comprise 20-30% of the study cohort.2) A sub-study of patterns of disease progression of 375 people (125 each of Caucasian, Asian and African-Caribbean origin; in each case containing subjects at high and low risk of renal progression). Additional reference GFR measurements will be undertaken after 1 and 2 years to enable a model of disease progression and error to be built.3) A biological variability study to establish reference change values for reference and test measures.4) A modelling study of the performance of monitoring strategies on detecting progression, utilising estimates of accuracy, patterns of disease progression and estimates of measurement error from studies 1), 2) and 3).5) A comprehensive cost database for each diagnostic approach will be developed to enable cost-effectiveness modelling of the optimal strategy.The performance of the estimating equations will be evaluated by assessing bias, precision and accuracy. Data will be modelled as a linear function of time utilising all available (maximum 7) time points compared with the difference between baseline and final reference values. The percentage of participants demonstrating large error with the respective estimating equations will be compared. Predictive value of GFR estimates and albumin-to-creatinine ratio will be compared amongst subjects that do or do not show progressive kidney function decline.

DISCUSSION

The eGFR-C study will provide evidence to inform the optimal GFR estimate to be used in clinical practice.

TRIAL REGISTRATION

ISRCTN42955626.

Performance of Cockcroft-Gault, MDRD, and CKD-EPI in estimating prevalence of renal function and predicting survival in the oldest old

Background

The question for prevalence estimation and validation of the various eGFRs in old age is still under debate. To assess renal function with increasing age, we estimated mean eGFR, in subjects aged 20–85 years. Furthermore, we assessed prevalence of eGFR in a population-based sample of 85 year olds and investigated the performance of these eGFRs in predicting mortality in the oldest old.

Methods

Renal function with increasing age was assessed in subjects aged 20–85 years from the Bronovo Study Cohort. We estimated prevalences of eGFRs and mortality risks in a population-based study of persons aged 85 years and older, the Leiden 85-plus Study. The GFRs were estimated by three different formulas.

Results

After the age of 70 years, the C-G tended to give relatively lower eGFRs. An eGFR < 60 was found in 90% of the subjects aged 85 years as calculated by C-G, in 55% of the subjects using MDRD and in 68% of the 85 year old subjects as calculated by CKD-EPI. When renal function was <30 ml/min/1.73 m², an increased mortality risk was observed by C-G (HR 1.9 (95% CI 1.1-3.3)), by MDRD (HR 3.5 (95% CI 1.8-6.7)), whereas by CKD-EPI significance was not reached (HR 2.4 (95% CI 0.9-6.4)).

Conclusions

Our study demonstrates that in subjects above age 70, C-G gives lower estimates of renal function when compared to MDRD and CKD-EPI. Furthermore, prevalence of renal dysfunction (CKD stage 1–3) at age 85 years was highest for C-G (90%), lowest for MDRD (55%), and 68% for CKD-EPI. Moreover, we found that in subjects aged 85 years MDRD predicted mortality best.

Is the Chronic Kidney Disease Epidemiology Collaboration creatinine-cystatin C equation useful for glomerular filtration rate estimation in the elderly?

Background

We aimed to evaluate the performance of the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) creatinine–cystatin C equation in a cohort of elderly Chinese participants.

Materials and methods

Glomerular filtration rate (GFR) was measured in 431 elderly Chinese participants by the technetium-99m diethylene-triamine-penta-acetic acid (^99mTc-DTPA) renal dynamic imaging method, and was calibrated equally to the dual plasma sample ^99mTc-DTPA-GFR. Performance of the CKD-EPI creatinine–cystatin C equation was compared with the Cockcroft–Gault equation, the re-expressed 4-variable Modification of Diet in Renal Disease (MDRD) equation, and the CKD-EPI creatinine equation.

Results

Although the bias of the CKD-EPI creatinine–cystatin C equation was greater than with the other equations (median difference, 5.7 mL/minute/1.73 m² versus a range from 0.4–2.5 mL/minute/1.73 m²; P<0.001 for all), the precision was improved with the CKD-EPI creatinine–cystatin C equation (interquartile range for the difference, 19.5 mL/minute/1.73 m² versus a range from 23.0–23.6 mL/minute/1.73 m²; P<0.001 for all comparisons), leading to slight improvement in accuracy (median absolute difference, 10.5 mL/minute/1.73 m² versus 12.2 and 11.4 mL/minute/1.73 m² for the Cockcroft–Gault equation and the re-expressed 4-variable MDRD equation, P=0.04 for both; 11.6 mL/minute/1.73 m² for the CKD-EPI creatinine equation, P=0.11), as the optimal scores of performance (6.0 versus a range from 1.0–2.0 for the other equations). Higher GFR category and diabetes were independent factors that negatively correlated with the accuracy of the CKD-EPI creatinine–cystatin C equation (β=−0.184 and −0.113, P<0.001 and P=0.02, respectively).

Conclusion

Compared with the creatinine-based equations, the CKD-EPI creatinine–cystatin C equation is more suitable for the elderly Chinese population. However, the cost-effectiveness of the CKD-EPI creatinine–cystatin C equation for clinical use should be considered.

Impact on cardiovascular risk follow-up from a shift to the CKD-EPI formula for eGFR reporting: a cross-sectional population-based primary care study

OBJECTIVE

To assess the impact on cardiovascular risk factor management in primary care by the introduction of chronic kidney disease epidemiological collaboration (CKD-EPI) for estimated-glomerular filtration rate (eGFR) reporting.

DESIGN AND SETTING

Cross-sectional study of routine healthcare provision in 47 primary care practices in The Netherlands with Modification of Diet and Renal Disease Study eGFR reporting.

METHODS

eGFR values were recalculated using CKD-EPI in patients with available creatine tests. Patients reclassified from CKD stage 3a to CKD stage 2 eGFR range were compared to those who remained in stage 3a for differences in demographic variables, blood pressure, comorbidity, medication usage and laboratory results.

RESULTS

Among the 60 673 adult patients (37% of adult population) with creatine values, applying the CKD-EPI equation resulted in a 16% net reduction in patients with CKD stage 3 or worse. Patients reclassified from stage 3a to 2 had lower systolic blood pressure (139.7 vs 143.3 mm Hg p<0.0001), higher diastolic blood pressure (81.5 vs 78.4 mm Hg p<0.0001) and higher cholesterol (5.4 vs 5.1 mmol/L p<0.0001) compared to those who remained in stage 3a. Of those reclassified out of a CKD diagnosis 463 (32%) had no comorbidities that would qualify for annual CVD risk factor assessment and 20 (12% of those with sufficient data) had a EuroSCORE CVD risk >20% within 10 years.

CONCLUSIONS

Use of the CKD-EPI equation will result in many patients being removed from CKD registers and the associated follow-up. Current risk factor assessment in this group may be lacking from routine data and some patients within this group are at an increased risk for cardiovascular events.

Glomerular function time trends in long-term survivors of childhood cancer: a longitudinal study

BACKGROUND

Impaired glomerular function is one of the health problems affecting childhood cancer survivors (CCS). It is unclear whether glomerular function deteriorates or recovers. We investigated time trends and predictors of glomerular function in CCS.

METHODS

We evaluated repeated observations of estimated glomerular filtration rate (GFR) and glomerular dysfunction (GFR <90 mL/min/1.73 m(2)) among adult five-year CCS treated in the EKZ/AMC between 1966 and 2003. Ifosfamide, cisplatin, carboplatin, high-dose (HD) methotrexate, HD-cyclophosphamide, radiotherapy to the kidney region, and nephrectomy (i.e., potentially nephrotoxic therapy) were investigated as predictors of glomerular function patterns over time in multivariable longitudinal analyses.

RESULTS

At a median follow-up of 21 years after diagnosis, glomerular function was assessed in 1,122 CCS aged ≥18 years. CCS treated with potentially nephrotoxic therapy had a significantly lower GFR and higher glomerular dysfunction probability up to 35 years after cancer diagnosis compared with CCS treated without nephrotoxic therapy (P < 0.001). Especially ifosfamide, cisplatin, and nephrectomy were associated with worse glomerular function that persisted during the entire follow-up period (P < 0.001). Glomerular function deteriorated over time in all CCS (P < 0.001). CCS treated with higher doses of cisplatin seem to have a higher deterioration rate as compared with other CCS (P < 0.005).

CONCLUSIONS

The loss in glomerular function starts early, especially for CCS treated with ifosfamide, higher doses of cisplatin, and nephrectomy, and seems to be persistent. We have an indication that CCS treated with higher doses of cisplatin experience faster decline than other CCS.

IMPACT

As glomerular function continues to deteriorate, CCS are at risk for premature chronic renal failure.

Validation of the Freiburg Comorbidity Index in 466 multiple myeloma patients and combination with the international staging system are highly predictive for outcome

BACKGROUND

The outcomes of MM patients vary considerably and depend on a variety of host- and disease-related risks. As yet, a comorbidity risk index in MM patients has neither been standardized nor validated.

PATIENTS AND METHODS

We conducted an initial analysis in 127 MM patients and developed the FCI, validating it in an independent cohort of 466 MM patients. The FCI includes patients' Karnofsky Performance Status, renal and lung disease status. We compared the prognostic information of this validated FCI with established comorbidity indices (Hematopoietic Cell Transplantation-Specific Comorbidity Index and Kaplan Feinstein), the International Staging System (ISS), MM therapy, and age.

RESULTS

Our validation confirmed that patients with 0, 1, or 2 to 3 FCI risk factors display significantly different overall survival (OS) of not reached, 86, and 39 months, respectively (P < .0001). Via multivariate analysis including the FCI, ISS, therapy, and age, the FCI retained its independent prognostic significance (P < .0015). The combination of the FCI and ISS allowed definition of 3 distinct subgroups with low-risk (FCI 0 and ISS I-II), intermediate-risk (all remaining), and high-risk (FCI 1-3 and ISS III) with OS probabilities at 5-years of 85%, 74%, and 42%, respectively (P < .0001).

CONCLUSION

Our validation analysis demonstrated that the FCI remains a reliable comorbidity index, is simpler to generate than other available comorbidity scores, and contributes valuable information to the ISS. Their combination allows the definition of low-, intermediate-, and high-risk patients. These results advocate use of the FCI in future prospective studies and might guide personalized treatment strategies.

Estimating the glomerular filtration rate in the general population using different equations: effects on classification and association

BACKGROUND/AIMS

Several formulas for glomerular filtration rate (GFR) estimation, based on serum creatinine or cystatin C, have been proposed. We assessed the impact of some of these equations on estimated GFR (eGFR) and chronic kidney disease (CKD) prevalence, and on the association with cardiovascular risk factors, in a general population sample characterized by a young mean age.

METHODS

We studied 1,199 individuals from three Alpine villages enrolled into the MICROS study. eGFR was obtained with the 4- and 6-parameter MDRD study equations, the Virga equation, and with the three CKD-EPI formulas for creatinine, cystatin C, and the combination of creatinine and cystatin C. We assessed the concordance between quantitative eGFR levels, CKD prevalence, and in terms of association with total, LDL, and HDL cholesterol.

RESULTS

The highest and lowest eGFR levels corresponded to the cystatin C-based and MDRD-4 equations, respectively. CKD prevalence varied from 1.8% (Virga) to 5.8% (MDRD-4). The CKD-EPI based on creatinine showed the highest agreement with all other equations. Agreement between methods was higher at lower eGFR levels, older age, and in the presence of diabetes and hypertension. Creatinine-based estimates of eGFR were associated with total and low-density lipoprotein but not high-density lipoprotein cholesterol. The opposite was observed for the cystatin C-based GFR.

CONCLUSION

GFR estimation is strongly affected by the chosen equation. Differences are more pronounced in healthy and younger individuals. To identify CKD risk factors, the choice of the equation is of secondary importance to the choice of the biomarker used in the formula. If eGFR is not calibrated to a gold standard GFR in the general population, reports about CKD prevalence should be considered with caution.

Comparison of estimating equations for the prediction of glomerular filtration rate in kidney donors before and after kidney donation

The aim of this study is to investigate the usefulness of the GFR-estimating equations to predict renal function in kidney donors before and after transplantation. We compared the performance of 24-hour-urine–based creatinine clearance (24 hr urine-CrCl), the Cockcroft-Gault formula (eGFR_CG), the Modification of Diet in Renal Disease equation (eGFR_MDRD), and the Chronic Kidney Disease Epidemiology Collaboration equation (eGFR_CKD-EPI) with technetium-diethylenetriaminepentaacetic acid (^99mTc-DTPA) clearance (mGFR) in 207 potential kidney donors and 108 uninephric donors. Before donation, eGFR_CKD-EPI showed minimal bias and did not show a significant difference from mGFR (P = 0.65, respectively) while 24 hr urine-CrCl and eGFR_MDRD significantly underestimated mGFR (P<0.001 for each). Precision and accuracy was highest in eGFR_CKD-EPI and this better performance was more dominant when renal function is higher than 90 mL·min⁻¹·1.73 m⁻². After kidney donation, eGFR_MDRD was superior to other equations in precision and accuracy in contrast to before donation. Within individual analysis, eGFR_MDRD showed better performance at post-donation compared to pre-donation, but eGFR_CKD-EPI and eGFR_CG showed inferior performance at post-donation. In conclusion, eGFR_CKD-EPI showed better performance compared to other equations before donation. In a uninephric donor, however, eGFR_MDRD is more appropriate for the estimation of renal function than eGFR_CKD-EPI.

Creatinine-or cystatin C-based equations to estimate glomerular filtration in the general population: impact on the epidemiology of chronic kidney disease

Background

Chronic kidney disease (CKD) is a major issue in public health. Its prevalence has been calculated using estimation of glomerular filtration rate (GFR) by the creatinine-based equations developed in the Modified Diet in Renal Disease (MDRD) and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) study. Recently, new equations based either on cystatin C (CKD-EPI Cys) or both cystatin and creatinine (CKD-EPI mix) have been proposed by the CKD-EPI consortium. The aim of this study was to measure the difference in the prevalence of stage 3 CKD, defined as an estimated GFR less than 60 mL/min/1.73 m², in a population using these four equations.

Methods

CKD screening was performed in the Province of Liège, Belgium. On a voluntary basis, people aged over 50 years have been screened. GFR was estimated by the four equations. Stage 3 CKD was defined as a GFR less than 60 mL/min/1.73 m².

Results

The population screened consisted of 4189 people (47% were men, mean age 63 ± 7y). Their mean serum creatinine and plasma cystatin C levels were 0.88 ± 0.21 mg/dL and 0.85 ± 0.17 mg/L, respectively. The prevalence of CKD in this population using the MDRD, the CKD-EPI, the CKD-EPI Cys and the CKD-EPI mix equations was 13%, 9.8%, 4.7% and 5%, respectively. The prevalence of CKD was significantly higher with the creatinine-based (MDRD and the CKD-EPI) equations compared to the new cystatin C-based equations.

Conclusions

Prevalence of CKD varies strongly depending on the method used to estimate GFR. Such discrepancies are of importance and must be confirmed and explained by additional studies, notably by studies using GFR measured with a reference method.

Trial registration

B70720071509

Risk stratification by 24-hour ambulatory blood pressure and estimated glomerular filtration rate in 5322 subjects from 11 populations

No previous study addressed whether in the general population estimated glomerular filtration rate (eGFR [Chronic Kidney Disease Epidemiology Collaboration formula]) adds to the prediction of cardiovascular outcome over and beyond ambulatory blood pressure. We recorded health outcomes in 5322 subjects (median age, 51.8 years; 43.1% women) randomly recruited from 11 populations, who had baseline measurements of 24-hour ambulatory blood pressure (ABP(24)) and eGFR. We computed hazard ratios using multivariable-adjusted Cox regression. Median follow-up was 9.3 years. In fully adjusted models, which included both ABP(24) and eGFR, ABP(24) predicted (P≤0.008) both total (513 deaths) and cardiovascular (206) mortality; eGFR only predicted cardiovascular mortality (P=0.012). Furthermore, ABP(24) predicted (P≤0.0056) fatal combined with nonfatal events as a result of all cardiovascular causes (555 events), cardiac disease (335 events), or stroke (218 events), whereas eGFR only predicted the composite cardiovascular end point and stroke (P≤0.035). The interaction terms between ABP(24) and eGFR were all nonsignificant (P≥0.082). For cardiovascular mortality, the composite cardiovascular end point, and stroke, ABP(24) added 0.35%, 1.17%, and 1.00% to the risk already explained by cohort, sex, age, body mass index, smoking and drinking, previous cardiovascular disease, diabetes mellitus, and antihypertensive drug treatment. Adding eGFR explained an additional 0.13%, 0.09%, and 0.14%, respectively. Sensitivity analyses stratified for ethnicity, sex, and the presence of hypertension or chronic kidney disease (eGFR <60 mL/min per 1.73 m(2)) were confirmatory. In conclusion, in the general population, eGFR predicts fewer end points than ABP(24). Relative to ABP(24), eGFR is as an additive, not a multiplicative, risk factor and refines risk stratification 2- to 14-fold less.

Prevalence of diminished kidney function in a representative sample of middle and older age adults in the Irish population

Background

The prevalence of chronic kidney disease (CKD) using available estimating equations with the Republic of Ireland is unknown.

Methods

A randomly selected population based cross-sectional study of 1,098 adults aged 45 years and older was conducted using data from the 2007 Survey of Lifestyle, Attitudes and Nutrition (SLÁN). Estimated Glomerular Filtration Rate (eGFR) was calculated from a single IDMS aligned serum creatinine using the CKD-EPI and the MDRD equations, and albumin to creatinine ratio was based on a single random urine sample.

Results

The sample clinical characteristics and demography was similar to middle and older age adults in the general Irish population, though with an underrepresentation of subjects >75 years and of males. All results are based on subjects with available blood and urine samples. Applying weighting to obtain survey based population estimates, using Irish population census data, the estimated weighted prevalence of CKD-EPI eGFR<60 mL/min/1.73m² was 11.6%, (95% confidence interval; 9.0, 14.2%), 12.0% ( 9.0, 14.2%) of men and 11.2% (7.3, 15.2%) of women. Unweighted prevalence estimates were similar at 11.8% (9.9, 13.8%). Albuminuria increased with lower CKD-EPI eGFR category. 10.1% of all subjects had albuminuria and an eGFR≥60 mL/min/1.73 m² giving an overall weighted estimated prevalence of National Kidney Foundation (NKF) defined CKD 21.3% (18.0, 24.6%), with the unadjusted estimate of 21.9% (19.5, 24.4%). MDRD related estimates for eGFR <60 mL/min/1.73 m², and NFK defined CKD were higher than CKD-EPI and differences were greater in younger and female subjects.

Conclusions

CKD is highly prevalent in middle and older aged adults within the Republic of Ireland. In this population, there is poor agreement between CKD-EPI and MDRD equations especially at higher GFRs. CKD is associated with lower educational status and poor self rated health.