Comparison of risk prediction using the CKD-EPI equation and the MDRD study equation for estimated glomerular filtration rate

Improved glomerular filtration rate estimation by an artificial neural network

Background

Accurate evaluation of glomerular filtration rates (GFRs) is of critical importance in clinical practice. A previous study showed that models based on artificial neural networks (ANNs) could achieve a better performance than traditional equations. However, large-sample cross-sectional surveys have not resolved questions about ANN performance.

Methods

A total of 1,180 patients that had chronic kidney disease (CKD) were enrolled in the development data set, the internal validation data set and the external validation data set. Additional 222 patients that were admitted to two independent institutions were externally validated. Several ANNs were constructed and finally a Back Propagation network optimized by a genetic algorithm (GABP network) was chosen as a superior model, which included six input variables; i.e., serum creatinine, serum urea nitrogen, age, height, weight and gender, and estimated GFR as the one output variable. Performance was then compared with the Cockcroft-Gault equation, the MDRD equations and the CKD-EPI equation.

Results

In the external validation data set, Bland-Altman analysis demonstrated that the precision of the six-variable GABP network was the highest among all of the estimation models; i.e., 46.7 ml/min/1.73 m² vs. a range from 71.3 to 101.7 ml/min/1.73 m², allowing improvement in accuracy (15% accuracy, 49.0%; 30% accuracy, 75.1%; 50% accuracy, 90.5% [P<0.001 for all]) and CKD stage classification (misclassification rate of CKD stage, 32.4% vs. a range from 47.3% to 53.3% [P<0.001 for all]). Furthermore, in the additional external validation data set, precision and accuracy were improved by the six-variable GABP network.

Conclusions

A new ANN model (the six-variable GABP network) for CKD patients was developed that could provide a simple, more accurate and reliable means for the estimation of GFR and stage of CKD than traditional equations. Further validations are needed to assess the ability of the ANN model in diverse populations.

Glomerular filtration rate in prospective living kidney donors

PURPOSE

Measurements of glomerular filtration rate (GFR) are frequently interpreted assuming a linear variation with age. Nonlinear relationships may give a better representation of the changes associated with normal ageing.

METHODS

This was a retrospective study of 904 subjects (468 women, 436 men; age range 18-84 years) undergoing assessment as prospective living kidney donors. GFR was evaluated from (51)Cr-EDTA plasma clearance using blood samples taken at 2, 3 and 4 h. The slope-intercept GFR was corrected for body surface area (BSA) using the Haycock formula and for the fast exponential using the Brochner-Mortensen equation. The relationship between age, gender and GFR was examined using best-fit curve analysis. Nonlinear relationships with age were explored using fractional polynomials.

RESULTS

There was no gender difference in BSA-corrected GFR over five decades of age (P = 0.40). However, female donors with a body mass index >30 kg/m(2) had a statistically significantly lower GFR than nonobese women (P < 0.01). The best-fit relationship between age and GFR was nonlinear and described using a fractional polynomial model of degree 1 (GFR = 103.9-0.0061 × Age(2) mL/min/1.73 m(2)) with a root mean standard error of 12.9 mL/min/1.73 m(2). The residual variance for this model was significantly smaller than for the best-fit linear model (P = 0.006).

CONCLUSIONS

GFR measurements in prospective living kidney donors are best corrected for age using a nonlinear relationship.

Are n-3 fatty acids still cardioprotective?

PURPOSE OF REVIEW

Several recent randomized trials and subsequent meta-analyses have questioned the value of n-3 fatty acid supplementation in cardiovascular disease risk reduction.

RECENT FINDINGS

This report focuses on four clinical trials published between 2010 and 2012 that have failed to show benefits of n-3 fatty acids, and on one meta-analysis from 2012 that used a controversial statistical approach in reaching a conclusion of no effect.

SUMMARY

The question of the extent to which n-3 fatty acid supplementation reduces risk for cardiovascular disease remains open. Future studies must be properly powered, use doses of n-3 fatty acids significantly higher than those provided in background diets, focus on patient populations with low n-3 fatty acid tissue levels, treat for longer periods of time, and consider the effects of these agents in the great majority of patients who are not on guideline-directed therapeutic regimens. The strong evidence-base from prospective cohort studies and the ever-deepening understanding of the cellular effects of long-chain n-3 fatty acids together support the need for these nutrients in reducing cardiovascular risk. Short-term findings from randomized controlled trials need to be interpreted in the light of all the evidence.

Estimated glomerular filtration rate in a population with normal to mildly reduced renal function as predictor of cardiovascular disease

BACKGROUND

While moderate and severe chronic kidney disease is an established independent risk factor for cardiovascular disease (CVD), the association of estimated glomerular filtration rate (eGFR) differences within the normal to mildly reduced range (from 60 to > 90 ml/min/1.73 m(2)) and CVD is less clear. Our aim was to examine the association of eGFR with incident CVD in a cohort of predominantly healthy subjects with normal to mildly reduced renal function.

DESIGN

Retrospective cohort study.

METHODS

We collected demographic, clinical, and laboratory parameters of subjects free of diabetes mellitus or CVD who attended annual medical screening examinations between 2001 and 2009. Main outcome measures were a new diagnosis of coronary artery disease (CAD) or cerebrovascular events (CVE).

RESULTS

During a median follow up of 4.3 years, among 10,909 subjects (mean eGFR 78.5 ± 12.2 ml/min/1.73 m(2)), 10.3% were diagnosed with CAD (n = 1025) or CVE (n = 94). Compared with subjects in the highest eGFR quintile (≥ 88.8 ml/min/1.73 m(2)), subjects in the lowest quintile (≤ 68.2 ml/min/1.73 m(2)) had a hazard ratio (HR) of 1.64 (95% CI 1.35-2.00; p < 0.001) for a CAD outcome, but this association was no longer significant after adjustment for age and other confounders (adjusted HR 1.08; p = 0.55). Similar findings were obtained for the association of eGFR with CVE.

CONCLUSIONS

In a predominantly healthy population with normal to mildly reduced renal function, lower eGFR is associated with higher risk for CVD; however, this association is not independent but merely reflects the association of age and other cardiovascular risk factors with reduced eGFR.

Associations of estimated glomerular filtration rate and albuminuria with mortality and renal failure by sex: a meta-analysis

OBJECTIVE

To assess for the presence of a sex interaction in the associations of estimated glomerular filtration rate and albuminuria with all-cause mortality, cardiovascular mortality, and end stage renal disease.

DESIGN

Random effects meta-analysis using pooled individual participant data.

SETTING

46 cohorts from Europe, North and South America, Asia, and Australasia.

PARTICIPANTS

2,051,158 participants (54% women) from general population cohorts (n=1,861,052), high risk cohorts (n=151,494), and chronic kidney disease cohorts (n=38,612). Eligible cohorts (except chronic kidney disease cohorts) had at least 1000 participants, outcomes of either mortality or end stage renal disease of ≥ 50 events, and baseline measurements of estimated glomerular filtration rate according to the Chronic Kidney Disease Epidemiology Collaboration equation (mL/min/1.73 m(2)) and urinary albumin-creatinine ratio (mg/g).

RESULTS

Risks of all-cause mortality and cardiovascular mortality were higher in men at all levels of estimated glomerular filtration rate and albumin-creatinine ratio. While higher risk was associated with lower estimated glomerular filtration rate and higher albumin-creatinine ratio in both sexes, the slope of the risk relationship for all-cause mortality and for cardiovascular mortality were steeper in women than in men. Compared with an estimated glomerular filtration rate of 95, the adjusted hazard ratio for all-cause mortality at estimated glomerular filtration rate 45 was 1.32 (95% CI 1.08 to 1.61) in women and 1.22 (1.00 to 1.48) in men (P(interaction)<0.01). Compared with a urinary albumin-creatinine ratio of 5, the adjusted hazard ratio for all-cause mortality at urinary albumin-creatinine ratio 30 was 1.69 (1.54 to 1.84) in women and 1.43 (1.31 to 1.57) in men (P(interaction)<0.01). Conversely, there was no evidence of a sex difference in associations of estimated glomerular filtration rate and urinary albumin-creatinine ratio with end stage renal disease risk.

CONCLUSIONS

Both sexes face increased risk of all-cause mortality, cardiovascular mortality, and end stage renal disease with lower estimated glomerular filtration rates and higher albuminuria. These findings were robust across a large global consortium.

Prediction of glomerular filtration rate in cancer patients by an equation for Japanese estimated glomerular filtration rate

BACKGROUND

Assessment of renal function is important for safe cancer chemotherapy, and eligibility criteria for clinical trials often include creatinine clearance. However, creatinine clearance overestimates glomerular filtration rate, and various new formulae have been proposed to estimate glomerular filtration rate. Because these were developed mostly in patients with chronic kidney disease, we evaluated their validity in cancer patients without kidney disease.

METHODS

Glomerular filtration rate was measured by inulin clearance in 45 Japanese cancer patients, and compared with creatinine clearance measured by 24-h urine collection as well as that estimated by the Cockcroft-Gault formula, Japanese estimated glomerular filtration rate developed in chronic kidney disease patients, the Modification of Diet in Renal Disease study equation and the Chronic Kidney Disease Epidemiology Collaboration equation. The Modification of Diet in Renal Disease study and Chronic Kidney Disease Epidemiology Collaboration equations were adjusted for the Japanese population by multiplying by 0.808 and 0.813, respectively.

RESULTS

The mean inulin clearance was 79.2 ± 18.7 ml/min/1.73 m(2). Bias values to estimate glomerular filtration rate for Japanese estimated glomerular filtration rate, the Cockcroft-Gault formula, creatinine clearance measured by 24-h urine collection, the 0.808 × Modification of Diet in Renal Disease study equation and the 0.813 × Chronic Kidney Disease Epidemiology Collaboration equation were 0.94, 9.75, 29.67, 5.26 and -0.92 ml/min/1.73 m(2), respectively. Precision (root-mean square error) was 14.7, 22.4, 39.8, 16.0 and 14.1 ml/min, respectively. Of the scatter plots of inulin clearance versus each estimation formula, the Japanese estimated glomerular filtration rate correlated most accurately with actual measured inulin clearance.

CONCLUSION

The Japanese estimated glomerular filtration rate and the 0.813 × Chronic Kidney Disease Epidemiology Collaboration equation estimated glomerular filtration rate with lower bias and higher precision than the other formulae. We therefore propose Japanese estimated glomerular filtration rate for the estimation of glomerular filtration rate in Japanese cancer patients.

Antimicrobial dosing in acute renal replacement

Acute kidney injury (AKI) is a common problem in hospitalized patients and is associated with significant morbidity and mortality. Two large trials showed no benefit from increased doses of renal replacement therapy (RRT) despite previous clinical data suggesting that increased clearance from RRT has beneficial effects. Since infection is the leading cause of death in AKI, my group and others hypothesized that increased RRT antibiotic clearance might create a competing morbidity. The data from my group, as well as those of other groups, show that many patients are underdosed when routine "1 size fits all" antibiotic dosing is used in patients with AKI receiving continuous RRT (CRRT). Here, concepts of drug distribution and clearance in AKI are briefly discussed and then 1 antibiotic (piperacillin) is discussed in depth to illustrate the challenges in applying the medical literature to clinical practice. The fact that published data on drug dosing in AKI and dialysis reflect the evolution of practice patterns and often do not apply to present prescribing habits is also discussed. A more general approach to drug dosing facilitates situation-specific prescribing by the nephrologist and critical care specialist.

Comparison of two creatinine-based equations for predicting decline in renal function in type 2 diabetic patients with nephropathy in a korean population

Aim. To compare two creatinine-based estimated glomerular filtration rate (eGFR) equations, the chronic kidney disease epidemiology collaboration (CKD-EPI) and the modification of diet in renal disease (MDRD), for predicting the risk of CKD progression in type 2 diabetic patients with nephropathy. Methods. A total of 707 type 2 diabetic patients with 24 hr urinary albumin excretion of more than 30 mg/day were retrospectively recruited and traced until doubling of baseline serum creatinine (SCr) levels was noted. Results. During the follow-up period (median, 2.4 years), the CKD-EPI equation reclassified 10.9% of all MDRD-estimated subjects: 9.1% to an earlier stage of CKD and 1.8% to a later stage of CKD. Overall, the prevalence of CKD (eGFR < 60 mL/min/1.73 m(2)) was lowered from 54% to 51.6% by applying the CKD-EPI equation. On Cox-regression analysis, both equations exhibited significant associations with an increased risk for doubling of SCr. However, only the CKD-EPI equation maintained a significant hazard ratio for doubling of SCr in earlier-stage CKD (eGFR ≥ 45 mL/min/1.73 m(2)), when compared to stage 1 CKD (eGFR ≥ 90 mL/min/1.73 m(2)). Conclusion. In regard to CKD progression, these results suggest that the CKD-EPI equation might more accurately stratify earlier-stage CKD among type 2 diabetic patients with nephropathy than the MDRD study equation.

Cohort profile: the chronic kidney disease prognosis consortium

The Chronic Kidney Disease Prognosis Consortium (CKD-PC) was established in 2009 to provide comprehensive evidence about the prognostic impact of two key kidney measures that are used to define and stage CKD, estimated glomerular filtration rate (eGFR) and albuminuria, on mortality and kidney outcomes. CKD-PC currently consists of 46 cohorts with data on these kidney measures and outcomes from >2 million participants spanning across 40 countries/regions all over the world. CKD-PC published four meta-analysis articles in 2010-11, providing key evidence for an international consensus on the definition and staging of CKD and an update for CKD clinical practice guidelines. The consortium continues to work on more detailed analysis (subgroups, different eGFR equations, other exposures and outcomes, and risk prediction). CKD-PC preferably collects individual participant data but also applies a novel distributed analysis model, in which each cohort runs statistical analysis locally and shares only analysed outputs for meta-analyses. This distributed model allows inclusion of cohorts which cannot share individual participant level data. According to agreement with cohorts, CKD-PC will not share data with third parties, but is open to including further eligible cohorts. Each cohort can opt in/out for each topic. CKD-PC has established a productive and effective collaboration, allowing flexible participation and complex meta-analyses for studying CKD.

Age and association of kidney measures with mortality and end-stage renal disease

CONTEXT

Chronic kidney disease (CKD) is prevalent in older individuals, but the risk implications of low estimated glomerular filtration rate (eGFR) and high albuminuria across the full age range are controversial.

OBJECTIVE

To evaluate possible effect modification (interaction) by age of the association of eGFR and albuminuria with clinical risk, examining both relative and absolute risks.

DESIGN, SETTING, AND PARTICIPANTS

Individual-level meta-analysis including 2,051,244 participants from 33 general population or high-risk (of vascular disease) cohorts and 13 CKD cohorts from Asia, Australasia, Europe, and North/South America, conducted in 1972-2011 with a mean follow-up time of 5.8 years (range, 0-31 years).

MAIN OUTCOME MEASURES

Hazard ratios (HRs) of mortality and end-stage renal disease (ESRD) according to eGFR and albuminuria were meta-analyzed across age categories after adjusting for sex, race, cardiovascular disease, diabetes, systolic blood pressure, cholesterol, body mass index, and smoking. Absolute risks were estimated using HRs and average incidence rates.

RESULTS

Mortality (112,325 deaths) and ESRD (8411 events) risks were higher at lower eGFR and higher albuminuria in every age category. In general and high-risk cohorts, relative mortality risk for reduced eGFR decreased with increasing age; eg, adjusted HRs at an eGFR of 45 mL/min/1.73 m2 vs 80 mL/min/1.73 m2 were 3.50 (95% CI, 2.55-4.81), 2.21 (95% CI, 2.02-2.41), 1.59 (95% CI, 1.42-1.77), and 1.35 (95% CI, 1.23-1.48) in age categories 18-54, 55-64, 65-74, and ≥75 years, respectively (P <.05 for age interaction). Absolute risk differences for the same comparisons were higher at older age (9.0 [95% CI, 6.0-12.8], 12.2 [95% CI, 10.3-14.3], 13.3 [95% CI, 9.0-18.6], and 27.2 [95% CI, 13.5-45.5] excess deaths per 1000 person-years, respectively). For increased albuminuria, reduction of relative risk with increasing age was less evident, while differences in absolute risk were higher in older age categories (7.5 [95% CI, 4.3-11.9], 12.2 [95% CI, 7.9-17.6], 22.7 [95% CI, 15.3-31.6], and 34.3 [95% CI, 19.5-52.4] excess deaths per 1000 person-years, respectively by age category, at an albumin-creatinine ratio of 300 mg/g vs 10 mg/g). In CKD cohorts, adjusted relative hazards of mortality did not decrease with age. In all cohorts, ESRD relative risks and absolute risk differences at lower eGFR or higher albuminuria were comparable across age categories.

CONCLUSIONS

Both low eGFR and high albuminuria were independently associated with mortality and ESRD regardless of age across a wide range of populations. Mortality showed lower relative risk but higher absolute risk differences at older age.

Assessing risk in chronic kidney disease: a methodological review

Chronic kidney disease (CKD) is an increasingly common public health issue associated with substantial morbidity and mortality. Risk prediction models provide a useful clinical and research framework for forecasting the probability of adverse events and stratifying patients with CKD according to risk; however, accurate absolute risk prediction requires careful model specification. Competing events that preclude the event of interest (for example, death in studies of end-stage renal disease) must be taken into account. Functional forms of predictor variables and underlying effect modification must be accurately specified; nonlinearity and possible interactions should be evaluated. The potential effect of measurement error should also be considered. Misspecification of any of these components can dramatically affect absolute risk prediction. Evaluation of prognostic models should encompass not only traditional tests of calibration and discrimination, such as the Hosmer-Lemeshow test of 'goodness of fit' and the area under the receiver operating curve, but also newer metrics, such as risk reclassification tables and net reclassification indices. The latter two tests are particularly useful when considering the addition of novel predictors to established models. Finally, models of absolute risk prediction should be internally and externally validated as they typically generalize only to populations with similar baseline characteristics and rates of competing events.

Associations of kidney disease measures with mortality and end-stage renal disease in individuals with and without hypertension: a meta-analysis

BACKGROUND

Hypertension is the most prevalent comorbidity in individuals with chronic kidney disease. However, whether the association of the kidney disease measures, estimated glomerular filtration rate (eGFR) and albuminuria, with mortality or end-stage renal disease (ESRD) differs by hypertensive status is unknown.

METHODS

We did a meta-analysis of studies selected according to Chronic Kidney Disease Prognosis Consortium criteria. Data transfer and analyses were done between March, 2011, and June, 2012. We used Cox proportional hazards models to estimate the hazard ratios (HR) of mortality and ESRD associated with eGFR and albuminuria in individuals with and without hypertension.

FINDINGS

We analysed data for 45 cohorts (25 general population, seven high-risk, and 13 chronic kidney disease) with 1,127,656 participants, 364,344 of whom had hypertension. Low eGFR and high albuminuria were associated with mortality irrespective of hypertensive status in the general population and high-risk cohorts. All-cause mortality risk was 1·1-1·2 times higher in individuals with hypertension than in those without hypertension at preserved eGFR. A steeper relative risk gradient in individuals without hypertension than in those with hypertension at eGFR range 45-75 mL/min per 1·73 m(2) led to much the same mortality risk at lower eGFR. With a reference eGFR of 95 mL/min per 1·73 m(2) in each group to explicitly assess interaction, adjusted HR for all-cause mortality at eGFR 45 mL/min per 1·73 m(2) was 1·77 (95% CI 1·57-1·99) in individuals without hypertension versus 1·24 (1·11-1·39) in those with hypertension (p for overall interaction=0·0003). Similarly, for albumin-creatinine ratio of 300 mg/g (vs 5 mg/g), HR was 2·30 (1·98-2·68) in individuals without hypertension versus 2·08 (1·84-2·35) in those with hypertension (p for overall interaction=0·019). We recorded much the same results for cardiovascular mortality. The associations of eGFR and albuminuria with ESRD, however, did not differ by hypertensive status. Results for chronic kidney disease cohorts were similar to those for general and high-risk population cohorts.

INTERPRETATION

Chronic kidney disease should be regarded as at least an equally relevant risk factor for mortality and ESRD in individuals without hypertension as it is in those with hypertension.

FUNDING

US National Kidney Foundation.

Associations of kidney disease measures with mortality and end-stage renal disease in individuals with and without diabetes: a meta-analysis

BACKGROUND

Chronic kidney disease is characterised by low estimated glomerular filtration rate (eGFR) and high albuminuria, and is associated with adverse outcomes. Whether these risks are modified by diabetes is unknown.

METHODS

We did a meta-analysis of studies selected according to Chronic Kidney Disease Prognosis Consortium criteria. Data transfer and analyses were done between March, 2011, and June, 2012. We used Cox proportional hazards models to estimate the hazard ratios (HR) of mortality and end-stage renal disease (ESRD) associated with eGFR and albuminuria in individuals with and without diabetes.

FINDINGS

We analysed data for 1,024,977 participants (128,505 with diabetes) from 30 general population and high-risk cardiovascular cohorts and 13 chronic kidney disease cohorts. In the combined general population and high-risk cohorts with data for all-cause mortality, 75,306 deaths occurred during a mean follow-up of 8·5 years (SD 5·0). In the 23 studies with data for cardiovascular mortality, 21,237 deaths occurred from cardiovascular disease during a mean follow-up of 9·2 years (SD 4·9). In the general and high-risk cohorts, mortality risks were 1·2-1·9 times higher for participants with diabetes than for those without diabetes across the ranges of eGFR and albumin-to-creatinine ratio (ACR). With fixed eGFR and ACR reference points in the diabetes and no diabetes groups, HR of mortality outcomes according to lower eGFR and higher ACR were much the same in participants with and without diabetes (eg, for all-cause mortality at eGFR 45 mL/min per 1·73 m(2) [vs 95 mL/min per 1·73 m(2)], HR 1·35; 95% CI 1·18-1·55; vs 1·33; 1·19-1·48 and at ACR 30 mg/g [vs 5 mg/g], 1·50; 1·35-1·65 vs 1·52; 1·38-1·67). The overall interactions were not significant. We identified much the same findings for ESRD in the chronic kidney disease cohorts.

INTERPRETATION

Despite higher risks for mortality and ESRD in diabetes, the relative risks of these outcomes by eGFR and ACR are much the same irrespective of the presence or absence of diabetes, emphasising the importance of kidney disease as a predictor of clinical outcomes.

FUNDING

US National Kidney Foundation.

GFR estimation using standardized cystatin C in kidney transplant recipients

BACKGROUND

The utility of serum cystatin C (SCysC) as a filtration marker in kidney transplantation is uncertain. We took advantage of the recent validation of a reference calibrator for SCysC and of newly developed CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) equations (2012) expressed for use with standardized SCysC level to reassess the performance of SCysC as a filtration marker in kidney transplant recipients.

STUDY DESIGN

Study of diagnostic test accuracy.

SETTING & PARTICIPANTS

670 kidney transplant recipients from 3 centers undergoing glomerular filtration rate (GFR) measurements from December 2006 to November 2012.

INDEX TEST

Estimated GFR (eGFR) using the 2012 SCysC-based and serum creatinine (SCr)/SCysC-based CKD-EPI equations (eGFR(cys) and eGFR(cr-cys), respectively) and the 2009 SCr-based CKD-EPI equation (eGFR(cr)), with SCysC and SCr measured at a single laboratory between April 2011 and June 2011.

REFERENCE TEST

Measured GFR (mGFR) using urinary clearance of inulin.

RESULTS

Bias (the difference between mGFR and eGFR) was significantly smaller for eGFR(cys) and eGFR(cr-cys) versus eGFR(cr) (-2.82 and -0.54 vs +4.4 mL/min/1.73 m(2), respectively; P < 0.001). Precision (standard deviation of the mean bias) also was better for eGFR(cys) and eGFR(cr-cys) versus eGFR(cr) (12 and 11 vs 13 mL/min/1.73 m(2) [P < 0.001 for both comparisons]). Accuracy (percentage of GFR estimates within 30% of mGFR) was greater for eGFR(cys) and eGFR(cr-cys) versus eGFR(cr) (81% and 86% vs 75%, respectively [P = 0.004 and P < 0.001]). Net reclassification index with respect to mGFR of 30 mL/min/1.73 m(2) for eGFR(cr-cys) and eGFR(cys) versus eGFR(cr) was 18.8% [95% CI, 8.6%-28.9%] and 22.5% [95% CI, 10.2%-34.9%].

LIMITATIONS

Patients were exclusively of European descent; association with transplant outcome was not evaluated.

CONCLUSIONS

Our data validate the use of both the newly developed SCysC-based and SCr/SCysC-based CKD-EPI equations (2012) in kidney transplant recipients. Both equations perform better than the SCr-based CKD-EPI equation (2009).

Estimated GFR and incident cardiovascular disease events in American Indians: the Strong Heart Study

BACKGROUND

In populations with high prevalences of diabetes and obesity, estimating glomerular filtration rate (GFR) by using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation may predict cardiovascular disease (CVD) risk better than by using the Modification of Diet in Renal Disease (MDRD) Study equation.

STUDY DESIGN

Longitudinal cohort study comparing the association of GFR estimated using either the CKD-EPI or MDRD Study equation with incident CVD outcomes.

SETTING & PARTICIPANTS

American Indians participating in the Strong Heart Study, a longitudinal population-based cohort with high prevalences of diabetes, CVD, and CKD.

PREDICTOR

Estimated GFR (eGFR) predicted using the CKD-EPI and MDRD Study equations.

OUTCOMES

Fatal and nonfatal cardiovascular events, consisting of coronary heart disease, stroke, and heart failure.

MEASUREMENTS

The association between eGFR and outcomes was explored in Cox proportional hazards models adjusted for traditional risk factors and albuminuria; the net reclassification index and integrated discrimination improvement were determined for the CKD-EPI versus MDRD Study equations.

RESULTS

In 4,549 participants, diabetes was present in 45%; CVD, in 7%; and stages 3-5 CKD, in 10%. During a median of 15 years, there were 1,280 cases of incident CVD, 929 cases of incident coronary heart disease, 305 cases of incident stroke, and 381 cases of incident heart failure. Reduced eGFR (<90 mL/min/1.73 m2) was associated with adverse events in most models. Compared with the MDRD Study equation, the CKD-EPI equation correctly reclassified 17.0% of 2,151 participants without incident CVD to a lower risk (higher eGFR) category and 1.3% (n=28) were reclassified incorrectly to a higher risk (lower eGFR) category.

LIMITATIONS

Single measurements of eGFR and albuminuria at study visits.

CONCLUSIONS

Although eGFR based on either equation had similar associations with incident CVD, coronary heart disease, stroke, and heart failure events, in those not having events, reclassification of participants to eGFR categories was superior using the CKD-EPI equation compared with the MDRD Study equation.

Incorporating glomerular filtration rate or creatinine clearance by the modification of diet in renal disease equation or the Cockcroft-Gault equations to improve the global accuracy of the Age, Creatinine, Ejection Fraction [ACEF] score in patients undergoing percutaneous coronary intervention

BACKGROUND

The aim of the present study was to appraise the comparative ability of different ACEF models incorporating glomerular filtration rate or creatinine clearance estimated by the Modification of Diet in Renal Disease [ACEFMDRD] or Cokcroft-Gault [ACEFCG] equations, respectively, over the original ACEF score (ACEFSrCr) in patients undergoing percutaneous coronary intervention (PCI).

METHODS

A total of 537 patients were analyzed by different measures of discrimination, calibration and net reclassification improvement (NRI).

RESULTS

A significant gradient in all-cause mortality was consistently seen with all the models at 30 days, 1 year and 5 years. The comparison of the three models showed that the best balance in terms of discrimination and calibration for all-cause mortality was offered by the ACEFCG at 30 days, the ACEFMDRD at 1 year and similarly by the ACEFCG and ACEFMDRD at 5 years. At 30 days, the NRI was +32.9% for ACEFMDRD over ACEFSrCr and +16% for ACEFCG over ACEFSrCr. At 1 year, the NRI was 13.8% for ACEFMDRD over ACEFSrCr and -7.8% for ACEFCG over ACEFSrCr. At 5 years, the NRI was +7.7% for both the ACEFMDRD and the ACEFCG over the ACEFSrCr.

CONCLUSIONS

In patients undergoing PCI, the ACEF score is associated with satisfactory early-, mid- and long-term discrimination regardless of the definition of renal function. However, incorporating glomerular filtration rate or creatinine clearance by the MDRD or CG formulas in the ACEF score yields superior calibration compared with the original SrCr-based equation, with the ACEFMDRD displaying superior reclassification ability over the ACEFCG and ACEFSrCr at 30 days and 1 year.

Diagnosis and management of chronic kidney disease in the elderly: a field of ongoing debate

Chronic kidney disease (CKD) is rather common in elderly adults who comprise the fastest growing subset of patients with end-stage renal disease (ESRD). At present, there are no specific guidelines and recommendations regarding early identification and management of elderly with CKD and the current CKD classification system may overestimate its exact prevalence. Screening strategies based either in a more accurate formula of estimation of GFR alone, or preferably in combination with proteinuria are urgently needed in order to raise awareness and to promote early diagnosis of CKD in the elderly. The number of elderly dialysis patients is also increasing and may lead to severe socio-economic problems worldwide. Both hemodialysis and peritoneal dialysis can sustain life, but present various disadvantages. There is a trend for home based dialysis therapies but the results are based on a small number of patients. Recent reports indicate that dialysis may not provide a clear benefit over non-dialysis regarding survival and quality of life issues, especially in the presence of extensive comorbidities. Current practices around the world regarding access to dialysis in the elderly are rather controversial, reflecting each country's health policies and ethical patterns. Although advanced age should not be considered as an absolute contraindication for kidney transplantation, it is not frequently offered in elderly ESRD patients due to the shortage of renal grafts. Global judgment of all physical and mental/psychological issues and full informed consent regarding possible complications are mandatory before listing elderly ESRD patients for kidney transplantation. As scientific evidence is rather scarce, there is an urgent need for prospective studies and an individualized approach for the diagnosis and treatment of the elderly CKD patients, in order to optimize care and improve quality of life in this special population.

Accuracy of the MDRD (Modification of Diet in Renal Disease) study and CKD-EPI (CKD Epidemiology Collaboration) equations for estimation of GFR in the elderly

BACKGROUND

Glomerular filtration rate (GFR) is a measure of kidney function, commonly estimated using equations that adjust serum creatinine concentration for age, race, and sex. The Modification of Diet in Renal Disease (MDRD) Study equation is widely used, but underestimates GFR at higher levels. The serum creatinine-based Chronic Kidney Disease-Epidemiology Collaboration (CKD-EPI(cr)) equation generally provides more accurate estimation at GFR >60 mL/min/1.73 m(2). Newer equations have been reported using cystatin C concentration either alone (CKD-EPI(cys)) or in combination with creatinine concentration (CKD-EPI(cr-cys)). None of these equations has been well validated in older people. We tested the accuracy of these equations in people 74 years or older compared with GFR measured by a reference method.

STUDY DESIGN

Diagnostic test evaluation in a prospective cohort.

SETTING & PARTICIPANTS

Participants (n = 394; median age, 80 [range, 74-97] years) recruited from nephrology clinics and the community.

INDEX TEST

GFR estimated using the MDRD Study, CKD-EPI(cr), CKD-EPI(cys) and CKD-EPI(cr-cys) equations.

REFERENCE TEST

GFR measured using an iohexol clearance method.

RESULTS

Median measured GFR was 53.4 (range, 7.2-100.9) mL/min/1.73 m(2). MDRD Study-, CKD-EPI(cr)-, and CKD-EPI(cr-cys)-estimated GFRs overestimated GFR (median differences of 3.5 [P< 0.001], 1.7 [P < 0.001], and 0.8 [P = 0.02] mL/min/1.73 m(2), respectively); the CKD-EPI(cys) equation was unbiased. Accuracy (percentage of estimates within 30% of measured GFR [P(30)]) was 81%, 83%, 86%, and 86% for the MDRD Study, CKD-EPI(cr), CKD-EPI(cys), and CKD-EPI(cr-cys) equations, respectively. Accuracy of the MDRD Study equation was inferior (P = 0.004) to the CKD-EPI(cr) equation at GFR >60 mL/min/1.73 m(2).

LIMITATIONS

Those of non-European ancestry were not included. For practical reasons, only a 4-hour sampling protocol was used for iohexol clearance.

CONCLUSIONS

The CKD-EPI(cr) equation appeared less biased and was more accurate than the MDRD Study equation. No equation achieved an ideal P(30) in the overall population. Our data suggest that GFR estimation is as satisfactory in older people of European ancestry as it has been reported to be in younger individuals.

Clinical pharmacology in old persons

The epidemiological transition, with a rapid increase in the proportion in the global population aged over 65 years from 11% in 2010 to 22% in 2050 and 32% in 2100, represents a challenge for public health. More and more old persons have multimorbidities and are treated with a large number of medicines. In advanced age, the pharmacokinetics and pharmacodynamics of many drugs are altered. In addition, pharmacotherapy may be complicated by difficulties with obtaining drugs or adherence and persistence with drug regimens. Safe and effective pharmacotherapy remains one of the greatest challenges in geriatric medicine. In this paper, the main principles of geriatric pharmacology are presented.