[Estimation of glomerular filtration rate in the elderly patient: Clinical implications in the use of antibiotics]

INTRODUCTION

In elderly, impaired kidney function may lead to relevant clinical implications, especially in drug dosage. There is no consensus on the best formula to estimate glomerular filtration rate (GFR) in this context. While the Cockcroft-Gault (CG) equation is the most used one in drug development, the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation is the most employed by clinical laboratories. The objective of this study is to analyze the differences and implications of using one or another equation when adjusting the dose of antibiotics.

MATERIAL AND METHODS

Cross-sectional study performed in patients older than 80 years admitted to an acute geriatric unit for infectious disease. Socio-demographic, functional, clinic, assistance and laboratory variables were gathered, calculating GFR according to CG and CKD-EPI. A concordance study between both equations, bivariate analysis and multiple linear regression were carried out.

RESULTS

100 patients were recruited, with mean age 88.5±4.2 years, and 54% women. A relative overestimation of 13.63mL/min was observed in GFR according to CKD-EPI, with a low-moderate concordance between both formulas. Greater need for dose adjustment of antibiotics with GC than with CKD-EPI was detected (38% vs. 23%; P<.001), as well as dosage discrepancies, especially with levofloxacin.

CONCLUSIONS

Both equations are not interchangeable in the elderly. When used to adjust antibiotic dose, CKD-EPI may overestimate GFR and may cause an increase in adverse reactions. Further studies should be carried out with the aim of reaching a consensus on the most appropriate equation for the elderly patient.

Renal changes and estimation of glomerular filtration rate using different equations in morbidly obese Egyptian patients

BACKGROUND AND AIMS

Obesity is a worldwide pandemic with multiple consequences including kidney affection. This study aimed to assess the effects of obesity on renal functions and to detect the most reliable formula of estimated glomerular filtration rate (eGFR) in morbidly obese patients.

METHODS

A cross-sectional, observational study was conducted on 82 morbidly obese patients. Anthropometric measurements were done for all patients and body adiposity (BAI) and visceral adiposity (VAI) indices were calculated after assessment of abdominal fat tissue analysis by computerized tomography (CT). Serum creatinine was incorporated into six different formulae of eGFR, then eGFR was compared with the 24-h measured creatinine clearance (CL_cr) values.

RESULTS

The mean body mass index was 55.8 ± 9.5 kg/m². Proteinuria and glomerular hyperfiltration (CL_cr > 130 ml/min/1.73 m²) were detected in 68.3% and 91.5% of the patients, respectively. Cockcroft-Gault formula using total (CCG-TBW-eGFR) and adjusted body water (CCG-AjBW-eGFR) had the nearest values to measured CL_Cr. These two formulae had a moderate reliability and the lowest percentage of error (30% and 23%, respectively). Visceral and total abdominal fat tissue surface area and volume assessed by CT were directly correlated to the 24-h urinary protein excretion (r = 0.32, 0.24, 0.37 and 0.34, respectively; p = 0.02, 0.03, 0.004 and 0.002, respectively).

CONCLUSIONS

Glomerular hyperfiltration and proteinuria are highly prevalent in morbidly obese patients. There is no ideal formula for GFR estimation in morbidly obese patients, however, TBW and AjBW incorporated into the Cockcroft-Gault can be helpful in those patients.

Prevalence of chronic kidney disease in Nigeria: systematic review of population-based studies

Background

The aim of this study was to identify and discuss published population-based studies carried out in Nigeria that have information on the prevalence of chronic kidney disease (CKD) and have also used the Kidney Disease Outcomes Quality Initiative (KDOQI) practice guidelines in defining CKD, with emphasis on the performance of three estimating equations for glomerular filtration rate (GFR) – Modification of Diet in Renal Disease (MDRD), Cock-croft–Gault, and CKD epidemiology collaboration (CKD-EPI) creatinine equation.

Materials and methods

A systematic literature search was carried out in Google, MEDLINE, PubMed, and AJOL database, with the aim of identifying relevant population-based studies with information on the prevalence of CKD in a location in Nigeria.

Results

Seven cross-sectional population-based studies were identified. Two of the studies used the Cockcroft–Gault and observed a prevalence of 24.4% and 26%. Four of the studies used the MDRD and the prevalences observed were 12.3%, 14.2%, 2.5%, and 13.4%. One of the studies used the CKD-EPI equation and the prevalence was 11.4%. The male to female ratios of CKD prevalence in six studies were 1:1.9, 0.8:1, 1:1.6, 1:2, 1:1.8, 1:1.4, and the observed risk factors in the studies were old age, obesity, diabetes mellitus, hypertension, family history of hypertension, family history of renal disease, low-income occupation, use of traditional medication, low hemoglobin, and abdominal obesity.

Conclusion

The prevalence of CKD was high but variable in Nigeria, influenced by the equation used to estimate the GFR. MDRD and CKD-EPI results are agreeable. There is a need for more population-based studies, with emphasis on repeating the GFR estimation after 3 months in subjects with GFR <60 mL/min/1.7 m².

Application of prescribing recommendations in older people with reduced kidney function: a cross-sectional study in general practice

BACKGROUND

Kidney function reduces with age, increasing the risk of harm from increased blood levels of many medicines. Although estimated glomerular filtration rate (eGFR) is reported for prescribing decisions in those aged ≥65 years, creatinine clearance (Cockcroft-Gault) gives a more accurate estimate of kidney function.

AIM

To explore the extent of prescribing outside recommendations for people aged ≥65 years with reduced kidney function in primary care and to assess the impact of using eGFR instead of creatinine clearance to calculate kidney function.

DESIGN AND SETTING

A cross-sectional survey of anonymised prescribing data in people aged ≥65 years from all 80 general practices (70 900 patients) in a north of England former primary care trust.

METHOD

The prevalence of prescribing outside recommendations was analysed for eight exemplar drugs. Data were collected for age, sex, actual weight, serum creatinine, and eGFR. Kidney function as creatinine clearance (Cockcroft-Gault) was calculated using actual body weight and estimated ideal body weight.

RESULTS

Kidney function was too low for recommended prescribing in 4-40% of people aged ≥65 years, and in 24-80% of people aged ≥85 years despite more than 90% of patients having recent recorded kidney function results. Using eGFR overestimated kidney function for 3-28% of those aged ≥65 years, and for 13-58% of those aged ≥85 years. Increased age predicted higher odds of having a kidney function estimate too low for recommended prescribing of the study drugs.

CONCLUSION

Prescribing recommendations when kidney function is reduced are not applied for many people aged ≥65 years in primary care. Using eGFR considerably overestimates kidney function for prescribing and, therefore, creatinine clearance (Cockcroft-Gault) should be assessed when prescribing for these people. Interventions are needed to aid prescribers when kidney function is reduced.

Comparison between Two-sample Method with 99mTc-diethylenetriaminepentaacetic acid, Gates' Method and Estimated Glomerular Filtration Rate Values by Formula Based Methods in Healthy Kidney Donor Population

Purpose of the Study:

Glomerular filtration rate (GFR) is the most important parameter for the assessment of renal function. GFR by plasma sampling technique is considered accurate in the selection of donors for renal transplantation. Estimated GFR (eGFR) calculations using Gates’ method and Modification of Diet in Renal Disease (MDRD) and Cockcroft–Gault (CG) equations are simple methods but have not been validated in the Indian population. Hence, we aimed to assess the correlation between these three techniques.

Materials and Methods:

The plasma sampling technique was done using two samples at 60 and 180 min after injection of 1 mCi (37MBq) ^99mTc-diethylenetriaminepentaacetic acid (^99mTc-DTPA) in 66 healthy donors. Age, sex, height, weight, and plasma creatinine were recorded. Normalized GFR (nGFR) by two-sample method and eGFR (for Gates’, MDRD, and CG) values were calculated using formulae.

Results:

There were 14 male and 52 female donors. Mean age was 46.56 ± 12.88 years (24–69 years). Mean height was 153.74 ± 8.35 cm, whereas mean weight was 56.97 ± 11.88 kg. Mean nGFR value was 80.4 for two-sample method while mean eGFR value for Gates’, CG, and MDRD were 83.3, 89.36, and 97.47 ml/min/1.73 m² (eligibility value at our institution = 70), respectively. While the correlation between nGFR and eGFR CG and MDRD was weak moderate (correlation coefficient = 0.5), nGFR and eGFR Gates’ had a moderate correlation (0.686). Mean total bias for eGFR Gates’, CG, and MDRD were 2.87, 8.93, and 17.0, respectively. P₃₀ of eGFR Gates’, CG and MDRD were 60.6%, 57.6%, and 62.1%, respectively.

Conclusions:

Due to the large variability in eGFR Gates’, CG and MDRD, nGFR estimation using the plasma sampling technique with ^99mTc-DTPA appears necessary while screening healthy donors for renal transplantation.

Clinical Decision Making in a Patient with Stage 5 CKD--Is eGFR Good Enough?

The development and widespread use of serum creatinine concentration-based prediction equations to calculate eGFR have been major advances for detection of patients with CKD and the epidemiologic study of CKD and its outcomes. However, these equations as well as those that also incorporate serum cystatin C concentration provide GFR estimates that, although reasonably precise on average, can differ markedly and in clinically important ways from actual GFR. Thus, it is important that clinicians who use these equations for clinical decision-making be familiar with their strengths and weaknesses and have an appreciation of their potential for error. More precise knowledge of actual GFR is important in certain clinical circumstances, including, as presented in this Attending Rounds, patients with stage 5 CKD, in whom decisions regarding dialysis initiation are necessary. Nephrologists should have the ability to accurately determine GFR when needed if clinical circumstances suggest inaccuracy of the calculated eGFR reported by the clinical laboratory.

Correlation of Microalbuminuria with Estimated GFR (eGFR) by Cockcroft-Gault and MDRD Formula in Type 2 Diabetics and Hypertensives

Increase in urine albumin excretion rate (AER) precede a fall in glomerular filtration rate in patients developing diabetic chronic kidney disease (CKD). Our results have shown that 7 (50 %) of diabetic and hypertensive individuals with decreased GFR do not have increased AER. In this cross-sectional study, we measured AER of 75 patients with type 2 diabetes and hypertension by immunoturbidimetric method. We correlated the results with eGFR values obtained by Cockcroft-Gault and MDRD method. The method used was not a compensated method. We measured serum creatinine by modified Jaffe's kinetic method in autoanalyzer XL-600. Analysis of data showed positive correlation between eGFR and microalbuminuria by both the methods with eGFR <60 mL/min/1.73 m(2). Pearson's correlation co-efficient (r) was 0.9 (p = 0.0001) by Cockcroft-Gault formula and 0.69 (p = 0.0063) by MDRD formula. Our results concluded that there was positive correlation between AER and eGFR <60 mL/min/1.73 m(2). We have recognized that these two parameters provide a complimentary benefit in management of cases with CKD.