Implications of using the MDRD or CKD-EPI equation instead of the Cockcroft-Gault equation for estimating renal function and drug dosage adjustment in elderly patients

The Ultrasound Renal Stress Test for the Assessment of Functional Renal Reserve in Kidney Transplantation: A Pilot Study in Living Donors

In the evolving landscape of nephrology and kidney transplants, assessing renal functional reserve (RFR) in living kidney donors is essential for ensuring donor safety and successful transplantation. This study explores the use of the Intra-Parenchymal Renal Resistive Index Variation (IRRIV) test, a novel non-invasive method, to measure RFR in living donors. Our observational study included 11 participants undergoing living kidney donations, evaluated using the IRRIV-based Renal Stress Test (RST) before and 12 months post-nephrectomy. The study demonstrated significant changes in creatinine and eGFR CKD-EPI levels post-donation, with an average creatinine rise from 69 to 97 µmol/L and a reduction in eGFR from 104 to 66 mL/min/1.73 m2. These variations align with the expected halving of nephron mass post-nephrectomy and the consequent recruitment of RFR and hyperfiltration in the remaining nephrons. This pilot study suggests that the IRRIV-based RST is a practical, safe, and reproducible tool, potentially revolutionizing the assessment of RFR in living kidney donors, with implications for broader clinical practice in donor eligibility evaluation, even in borderline renal cases. Furthermore, it confirms the feasibility of RST in living kidney donors and allows us to assess the sample size in 48 donors for a future study.

Population Pharmacokinetics of Digoxin in Nonagenarian Patients: Optimization of the Dosing Regimen

OBJECTIVE

The aim of this study was to develop a population pharmacokinetic model of digoxin in patients over 90 years old and to propose an equation for adjusting digoxin dose in this population.

METHODS

We included 326 nonagenarian patients admitted to Severo Ochoa University Hospital (Spain) who received digoxin and were under therapeutic drug monitoring. All data were retrospectively collected, and population modeling was performed with non-linear mixed-effect modeling software (NONMEM®). One- and two-compartment models were tested to calculate digoxin clearance (Cl), volume of distribution (Vd), absorption rate constant (Ka), and bioavailability (bioavailable fraction, F). The covariates were evaluated by stepwise covariate model building, and the final model was internally validated by bootstrap analysis with 1000 resamples. External validation was performed with another population of 95 patients with the same characteristics as the modeling group.

RESULTS

The population was 26% males, with a mean age of 93.2 years (90-103 years), mean creatinine 1.11 mg/dL (0.42-3.81 mg/dL), and mean total body weight 61.2 kg (40-100 kg). The pharmacokinetics of digoxin were best described by a one-compartment model (ADVAN2 TRANS2), with first-order conditional estimation with interaction. The covariates with influence on our model were creatinine clearance based on the Cockcroft-Gault equation (CG), serum potassium (K), co-administration of loop diuretics, and sex: Cl/F = 4.55 · (CG/36.4)0.468 · 0.83LD · 1.21SEX; Vd/F = 355 · (K/4.3)-0.849; Ka = 1.22 h-1 [where LD indicates loop diuretics (1 for administered, 0 for otherwise) and SEX indicates patient sex (1 for male, 0 for female)]. Based on our results, we proposed an equation to adjust the digoxin dosing regimen in nonagenarian patients: dose (mg) = 0.144 · (CG/36.4)0.468 · 0.83LD · 1.21SEX.

CONCLUSIONS

The greatest influence on digoxin clearance came from renal function calculated by the Cockcroft-Gault equation. Vd was decreased by K. The model developed showed a precise predictive performance to be applied for therapeutic drug monitoring.

Recent advances in dosage form design for the elderly: a review

INTRODUCTION

With the increase in the elderly population and the prevalence of multiple medical conditions, medication adherence, and efficacy have become crucial for the effective management of their health. The aging population faces unique challenges that need to be addressed through advancements in drug delivery systems and formulation technologies.

AREAS COVERED

The current review highlights the recent advances in dosage form design for older individuals, with consideration of their specific physiological and cognitive changes. Various dosage forms, such as modified-release tablets/capsules, chewable tablets, and transdermal patches, can be tailored to meet the specific needs of elderly patients. Advancements in drug delivery systems, such as nanotherapeutics, additive manufacturing (three-dimensional printing), and drug-food combinations, improve drug delivery and efficacy and overcome challenges, such as dysphagia and medication adherence.

EXPERT OPINION

Regulatory guidelines and considerations are crucial in ensuring the safe utilization of medications among older adults. Important factors to consider include geriatric-specific guidelines, safety considerations, labeling requirements, clinical trial considerations, and adherence and accessibility considerations.

Implementing evidence-based anticoagulant prescribing: User-centered design findings and recommendations

Background

Direct oral anticoagulants (DOACs) are widely used medications with an unacceptably high rate of prescription errors and are a leading cause of adverse drug events. Clinical decision support, including medication alerts, can be an effective implementation strategy to reduce prescription errors, but quality is often inconsistent. User-centered design (UCD) approaches can improve the effectiveness of alerts.

Objectives

To design effective DOAC prescription alerts through UCD and develop a set of generalizable design recommendations.

Methods

This study used an iterative UCD process with practicing clinicians. In three rapid iterative design and assessment stages, prototype alert designs were created and refined using a test electronic health record (EHR) environment and simulated patients. We identified key emergent themes across all user observations and interviews. The themes and final designs were used to derive a set of design guidelines.

Results

Our UCD sample comprised 13 prescribers, including advanced practice providers, physicians in training, primary care physicians, and cardiologists. The resulting alert designs embody our design recommendations, which include establishing intended indication, clarifying dosing by renal function, tailoring alert language in drug interactions, facilitating trust in alerts, and minimizing interaction overhead.

Conclusions

Through a robust UCD process, we have identified key recommendations for implementing medication alerts aimed at improving evidence-based DOAC prescribing. These recommendations may be applicable to the implementation of DOAC alerts in any EHR systems.

Ultrasonographic Intraparenchymal Renal Resistive Index Variation for Assessing Renal Functional Reserve in Patients Scheduled for Cardiac Surgery: A Pilot Study

INTRODUCTION

Cardiac surgery-associated acute kidney injury (CSA-AKI) is a common complication in patients undergoing cardiac surgery. Preoperative renal functional reserve (RFR) has been demonstrated to be highly predictive of CSA-AKI. We have previously demonstrated that intraparenchymal renal resistive index variation (IRRIV) measured by ultrasound (US) can identify the presence of RFR in healthy individuals. This study aimed (1) to examine the correlation between the US IRRIV test and RFR measured through the protein loading test in patients undergoing elective cardiac surgery and (2) to determine the value of the 2 methods for predicting occurrence of AKI or subclinical AKI after cardiac surgery.

METHODS

Consecutive patients scheduled for cardiac surgery were enrolled for this pilot study. The protein loading test and the IRRIV test were performed in all patients 2 days before cardiac surgery. Correlation between IRRIV and RFR was tested using Pearson correlation analysis. Association between presence of RFR and positive IRRIV test, presence of RFR and AKI and subclinical AKI, and positive IRRIV test and AKI and subclinical AKI was evaluated using logistic regression analysis. Receiver operating characteristic (ROC) curve analysis was performed to evaluate the values of IRRIV for predicting RFR, RFR for predicting AKI and subclinical AKI, and IRRIV for predicting AKI and subclinical AKI.

RESULTS

Among the 31 patients enrolled, significant association was found between IRRIV and RFR (r = 0.81; 95% CI: 0.63-0.90; p < 0.01). The association between RFR and IRRIV was described in 27/31 (87.1%) patients. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the IRRIV test were 100, 84, 60, and 100%, respectively. In ROC curve analysis, the area under the curve (AUC) was 0.80 (95% CI: 0.64-0.96). After cardiac surgery, 1/31 (3.2%) patient had AKI and 12/31 (38.7%) had subclinical AKI. RFR predicted subclinical AKI (odds ratio [OR] = 0.93; 95% CI: 0.87-0.98; p = 0.02). The sensitivity, specificity, PPV, and NPV of the RFR were 61, 88.8, 80, and 76%, respectively; the AUC was 0.75 (95% CI: 0.59-0.91). IRRIV predicts subclinical AKI (OR = 0.79; 95% CI: 0.67-0.93; p = 0.005). The sensitivity, specificity, PPV, and NPV of the IRRIV test were 46.1, 100, 100, and 72%, respectively; the AUC was 0.73 (95% CI: 0.58-0.87).

CONCLUSION

This pilot study suggests that a positive IRRIV test can significantly predict the presence of RFR in patients scheduled for cardiac surgery. RFR measured by the protein loading test or by the US IRRIV test can predict the occurrence of subclinical postoperative AKI. The findings of this study need to be confirmed in large patient cohorts.

Area under the Curve-Based Dosing of Vancomycin in Critically Ill Patients Using 6-Hour Urine Creatinine Clearance Measurement

BACKGROUND

The area under the curve- (AUC-) guided vancomycin dosing is the best strategy for individualized therapy in critical illnesses. Since AUC can be calculated directly using drug clearance (CLvan), any parameter estimating CLvan will be able to achieve the goal of 24-hour AUC (AUC24 h). The present study was aimed to determine CLvan based on 6-hour urine creatinine clearance measurement in critically ill patients with normal renal function.

METHOD

23 adult critically ill patients with an estimated glomerular filtration rate (eGFR) ≥60 mL/min who received vancomycin infusion were enrolled in this pilot study. Vancomycin pharmacokinetic parameters were determined for each patient using serum concentration data and a one-compartment model provided by MONOLIX software using stochastic approximation expectation-maximization (SAEM) algorithm. Correlation of CLvan with the measured creatinine clearance in 6-hour urine collection (CL6 h) and estimated creatinine clearance by the Cockcroft-Gault formula (CLCG) was investigated.

RESULTS

Data analysis revealed that CL6 h had a stronger correlation with CLvan rather than CLCG (r = 0.823 vs. 0.594; p < 0.001 vs. 0.003). The relationship between CLvan and CL6 h was utilized to develop the following equation for estimating CLvan: CLvan (mL/min) = ─137.4 + CL6 h (mL/min) + 2.5 IBW (kg) (R 2  = 0.826, p < 0.001). Regarding the described model, the following equation can be used to calculate the empirical dose of vancomycin for achieving the therapeutic goals in critically ill patients without renal impairment: total daily dose of vancomycin (mg) = (─137.4CL6-h (mL/min) + 2.5 IBW (kg)) × 0.06 AUC24 h (mg.hr/L).

CONCLUSION

For AUC estimation, CLvan can be obtained by collecting urine in a 6-hour period with good approximation in critically ill patients with normal renal function.

Accuracy of freely available online GFR calculators using the CKD-EPI equation

Purpose

Estimated glomerular filtration rate (eGFR) as calculated by the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation is used for detection of chronic kidney disease and drug dose adjustment. The purpose of the present study was to investigate the accuracy of freely available eGFR online calculators.

Methods

All identified CKD-EPI online calculators were run with five reference cases differing in age, sex, serum creatinine, and ethnicity. Conversion from eGFR_indexed (unit ml/min per 1.73 m²) to eGFR_non-indexed (unit ml/min) and creatinine unit from milligramme/decilitre to micromole/litre was checked, if available.

Results

Only 36 of 47 calculators (76.6%) produced accurate eGFR results for all reference cases. Eight of 47 (17.0%) calculators were considered as faulty because of errors relating to ethnicity (4 calculators), to conversion of the eGFR unit (2 calculators), to erroneous eGFR values without obvious explanation (2 calculators), to conversion of the creatinine unit (1 calculator), and to an error in the eGFR unit displayed (1 calculator). Overall, 28 errors were found (range 59 to 147% of the correct eGFR value), the majority concerning calculation of eGFR_indexed and the conversion to eGFR_non-indexed. Only 7 of 47 (14.9%) calculators offered conversion of the eGFR unit.

Conclusions

Erroneous calculations that might lead to inappropriate clinical decision-making were found in 8 of 47 calculators. Thus, online calculators should be evaluated more thoroughly after implementation. Conversion of eGFR units that might be needed for drug dose adjustments should be implemented more often.

Electronic supplementary material

The online version of this article (10.1007/s00228-020-02932-x) contains supplementary material, which is available to authorized users.

The relationship between intra-parenchymal renal resistive index variation and renal functional reserve in healthy subjects

BACKGROUND

Renal functional reserve can be used as a clinical tool for risk stratification of patients undergoing potentially nephrotoxic procedures. Ultrasound assessment of intra-parenchymal renal resistive index variation-IRRIV test-has been recently proposed as a safe, reproducible, inexpensive and easy to perform technique to identify the presence of renal functional reserve. The present study has been designed to externally validate the IRRIV test in a validation cohort of healthy subjects.

METHODS

We examined data from a group of 47 healthy subjects undergoing protein loading and IRRIV testing. The correlation between IRRIV and renal functional reserve was tested using Pearson correlation analysis. Concordance between presence of renal functional reserve (i.e. a value of renal functional reserve ≥ 15 ml/min/1.73 m²) and IRRIV was evaluated using logistic regression analysis.

RESULTS

We found a significant correlation between IRRIV and renal functional reserve (Pearson correlation coefficient = 0.83 [95% confidence interval (CI) 0.71-0.90; p < 0.01]). Concordance between the presence of renal functional reserve and the IRRIV test was described in 45 (95.7%) subjects. In particular, a negative IRRIV test correctly predicted the absence of renal functional reserve in 5 subjects, while a positive IRRIV test correctly predicted the presence of renal functional reserve in 40 subjects. Only two subjects were incorrectly classified by the IRRIV test. IRRIV predicts renal functional reserve with a ROC-AUC of 0.86 [CI 95% 0.68-1].

CONCLUSIONS

The IRRIV test is an ultrasound technique that significantly predicts the presence and the degree of renal functional reserve in healthy subjects.

Comparison of five glomerular filtration rate estimating equations as predictors of acute kidney injury after cardiovascular surgery

We aimed to compare the ability of preoperative estimated glomerular filtration rate (eGFR), calculated using five different equations, to predict adverse renal outcomes after cardiovascular surgery. Cohorts of 4,125 adult patients undergoing elective cardiovascular surgery were evaluated. Preoperative eGFR was calculated using the Cockcroft-Gault, Modification of Diet in Renal Disease (MDRD) II, re-expressed MDRD II, Chronic Kidney Disease Epidemiology Collaboration, and Mayo quadratic (Mayo) equations. The primary outcome was postoperative acute kidney injury (AKI), defined by Kidney Disease: Improving Global Outcomes Definition and Staging criteria based on changes in serum creatinine concentrations within 7 days. The MDRD II and Cockcroft-Gault equations yielded the highest (88.1 ± 26.7 ml/min/1.73 m2) and lowest (79.6 ± 25.5 ml/min/1.73 m2) mean eGFR values, respectively. Multivariable analysis showed that a preoperative decrease in renal function according to all five equations was independently associated with an increased risk of postoperative AKI. The area under the receiver operating characteristics curve for predicting postoperative AKI was highest for the Mayo equation (0.713). Net improvements in reclassification and integrated discrimination were higher for the Mayo equation than for the other equations. The Mayo equation was the most accurate in predicting postoperative AKI in patients undergoing cardiovascular surgery.

Differences in Kidney Function Estimates Based on Creatinine and/or Cystatin C in Non-Traumatic Amputation Patients and Their Impact on Drug Prescribing

Accurate kidney function estimates are necessary when prescribing renally-eliminated medications. Our objectives were to investigate how amputation affects estimated glomerular filtration rate (eGFR) and to determine if dosing recommendations differ among different eGFR equations. In a cohort study of non-traumatic amputation patients, eGFR based on creatinine and/or cystatin C were measured before and after amputation. Prescribed, renally-eliminated medications were compared with dosing guidelines in Renbase^®. Data from 38 patients with a median age of 75 years were analyzed. The median (range) eGFR was 65 (15⁻103), 38 (13⁻79), and 48 (13⁻86) mL/min/1.73 m² before amputation and 80 (22⁻107), 51 (13⁻95), and 62 (16⁻100) mL/min/1.73 m² after amputation for eGFR_Creatinine, eGFR_CystatinC, and eGFR_Combined, respectively (p < 0.01). From before to after amputation, eGFR increased on average by 8.5, 6.1, and 7.4 mL/min/1.73 m² for eGFR_Creatinine, eGFR_CystatinC, and eGFR_Combined (all p < 0.01), respectively. At least one renally-eliminated medication was prescribed at a higher dose than recommended in 37.8% of patients using eGFR_CystatinC, 17.6% using eGFR_Combined and 10.8% using eGFR_Creatinine. In conclusion, amputation affects eGFR regardless of the eGFR equations. The differences among equations would impact prescribing of renally-eliminated medications, particularly when switching from creatinine to cystatin C.

Prescription of DPP-4 Inhibitors to Patients With Adult Type 2 Diabetes Mellitus and Creatinine Clearance >50 mL/min: The UK Primary Care Experience

The aim of the study was to examine the extent to which patients with type 2 diabetes mellitus (T2DM) initiating a dipeptidyl peptidase 4 (DPP-4) inhibitor, who had no recorded objective evidence to justify dose adjustment, were initiated on the manufacturer-specified dose. Adopting a cross-sectional study design and using data from the UK General Practice, this study showed that at least 10% of patients with T2DM and a creatinine clearance level >50 mL/min initiating treatment with a DPP-4 inhibitor were prescribed a dose lower than specified in the Summary of Product Characteristics. This study provides further insights regarding DPP-4 inhibitor dose selection with respect to manufacturer specification in relation to renal function.

Comparison of the Cockcroft-Gault, MDRD and CKD-EPI equations for estimating ganciclovir clearance

AIMS

Accurately estimating kidney function is essential for the safe administration of renally cleared drugs such as ganciclovir. Current practice recommends adjusting renally eliminated drugs according to the Cockcroft-Gault equation. There are no data on the utility of the Modification of Diet in Renal Disease (MDRD) and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations in ganciclovir dosing. To evaluate which renal function equation best predicts ganciclovir clearance.

METHODS

The performance of the Cockcroft-Gault equation, isotope dilution mass spectrometry (IDMS)-traceable 4-variable MDRD study (MDRD4-IDMS) equation and CKD-EPI equation in determining ganciclovir clearance were assessed retrospectively in patients treated with ganciclovir from 2004-2015. The MDRD4-IDMS and CKD-EPI equations adjusted to individual body surface area (MDRD4-IDMS·BSA and CKD-EPI·BSA, respectively) were also evaluated. Patients with intravenous ganciclovir peak and trough concentrations in their medical records were included in the study. Ganciclovir clearance was calculated from serum concentrations using a one-compartment model. The five equations were compared based on their predictive ability, the coefficient of determination, through a linear regression analysis. The results were validated in a group of patients.

RESULTS

One hundred patients were included in the final analysis. Seventy-four patients were analysed in the learning group and 26 in the validation group. The coefficient of determination was 0.281 for Cockcroft-Gault, 0.301 for CKD-EPI·BSA, 0.308 for MDRD4-IDMS·BSA, 0.324 for MDRD4-IDMS and 0.360 for CKD-EPI. Subgroup analysis also showed that CKD-EPI is a better predictor of ganciclovir clearance. Analysis of the validation group confirmed these results.

CONCLUSIONS

The CKD-EPI equation correlates better with ganciclovir clearance than the Cockcroft-Gault and MDRD4-IDMS equations, even the clinical difference between the equations is scarce.

Effects of cilostazol and renin-angiotensin system (RAS) blockers on the renal disease progression of Korean patients: a retrospective cohort study

Background Decline in estimated glomerular filtration rate (eGFR) is an important surrogate marker for the assessment of renal function. Addition of a second agent to angiotensin-converting-enzyme inhibitor (ACEI) or angiotensin II receptor blocker (ARB) treatment may improve current therapeutic strategies aimed at suppressing renal disease progression. Objective To determine the effect of cilostazol in combination with ACEI or ARB treatment on the decline in eGFR. Setting A tertiary hospital in Korea. Method In an observational cohort study, we analyzed 5505 patients who were prescribed ACEI or ARB and cilostazol or other antiplatelet agents. Main outcome measure The primary outcome assessed was worsening of renal function defined as a 30% decline in eGFR per year. The secondary outcomes included commencement of dialysis, renal transplantation, death, myocardial infarction, and ischemic stroke. Results Following propensity score matching, eGFR decreased over time in the majority of patients, but the decline was less in patients in the cilostazol treated (CT) group of stage 1-2 category compared to the cilostazol untreated (CU) group (OR 0.80; 95% CI 0.66-0.98). In the subgroup analysis, the strongest effect in slowing eGFR decline was observed in CT patients at a high risk of diabetes (OR 0.782; 95% CI 0.615-0.993) and the elderly (OR 0.693; 95% CI 0.504-0.953) in the stage 1-2 category. No significant increase in cardiovascular risk was observed between the CT and CU groups. Conclusion Treatment with cilostazol plus ACEI or ARB was observed to prevent worsening of renal progression in patients in the stages 1-2.

Renal function estimation and Cockroft-Gault formulas for predicting cardiovascular mortality in population-based, cardiovascular risk, heart failure and post-myocardial infarction cohorts: The Heart 'OMics' in AGEing (HOMAGE) and the high-risk myocardial infarction database initiatives

BACKGROUND

Renal impairment is a major risk factor for mortality in various populations. Three formulas are frequently used to assess both glomerular filtration rate (eGFR) or creatinine clearance (CrCl) and mortality prediction: body surface area adjusted-Cockcroft-Gault (CG-BSA), Modification of Diet in Renal Disease Study (MDRD4), and the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation. The CKD-EPI is the most accurate eGFR estimator as compared to a "gold-standard"; however, which of the latter is the best formula to assess prognosis remains to be clarified. This study aimed to compare the prognostic value of these formulas in predicting the risk of cardiovascular mortality (CVM) in population-based, cardiovascular risk, heart failure (HF) and post-myocardial infarction (MI) cohorts.

METHODS

Two previously published cohorts of pooled patient data derived from the partners involved in the HOMAGE-consortium and from four clinical trials - CAPRICORN, EPHESUS, OPTIMAAL and VALIANT - the high risk MI initiative, were used. A total of 54,111 patients were included in the present analysis: 2644 from population-based cohorts; 20,895 from cardiovascular risk cohorts; 1801 from heart failure cohorts; and 28,771 from post-myocardial infarction cohorts. Participants were patients enrolled in the respective cohorts and trials. The primary outcome was CVM.

RESULTS

All formulas were strongly and independently associated with CVM. Lower eGFR/CrCl was associated with increasing CVM rates for values below 60 mL/min/m². Categorical renal function stages diverged in a more pronounced manner with the CG-BSA formula in all populations (higher χ² values), with lower stages showing stronger associations. The discriminative improvement driven by the CG-BSA formula was superior to that of MDRD4 and CKD-EPI, but remained low overall (increase in C-index ranging from 0.5 to 2 %) while not statistically significant in population-based cohorts. The integrated discrimination improvement and net reclassification improvement were higher (P < 0.05) for the CG-BSA formula compared to MDRD4 and CKD-EPI in CV risk, HF and post-MI cohorts, but not in population-based cohorts. The CKD-EPI formula was superior overall to MDRD4.

CONCLUSIONS

The CG-BSA formula was slightly more accurate in predicting CVM in CV risk, HF, and post-MI cohorts (but not in population-based cohorts). However, the CG-BSA discriminative improvement was globally low compared to MDRD4 and especially CKD-EPI, the latter offering the best compromise between renal function estimation and CVM prediction.