Creatinine-based equations predicting chronic kidney disease after kidney donation

A prospective study of living kidney donors: 6 years follow-up from a cardiovascular disease risk perspective

OBJECTIVE:

The purpose of this prospective study was to evaluate the clinical, laboratory, and donation-specific outcomes of living kidney donors 6 years after donation.

METHODS:

We included a total of 93 kidney donors and 54 age- and sex-matched individuals as control group through a type 2 cohort consecutive recruitment. We detected kidney function abnormalities and the presence of hypertension, diabetes, and cardiovascular events during the 6 years follow-up period.

RESULTS:

The mean serum creatinine levels were higher (p<0.001), and the estimated glomerular filtration rate levels were lower (p<0.001) in living kidney donors 6 years after donation when compared with controls. The protein/creatinine ratio of the study population was also higher (p=0.014). There was no difference in outcomes between the groups for end-stage kidney disease and cardiovascular mortality. A higher rate of new-onset hypertension (6.4 vs. 32.9%), diabetes mellitus (0.0 vs. 4.3%), chronic kidney disease (0.0 vs. 2.1%), and cardiovascular disease (0.0 vs. 2.1%) was demonstrated among donors 6 years after donation (p<0.001, respectively).

CONCLUSION:

Our data have demonstrated that the reduction in Glomerular filtration rate induced by kidney donation might cause an increase in adverse renal and cardiovascular events.

Clinical Impact of a Protocolized Kidney Donor Follow-up System

BACKGROUND

Adequate kidney donor management after donation is increasingly emphasized due to concerns of renal function impairment after nephrectomy with increasing life expectancy. In this study, the clinical impact of a protocolized kidney donor follow-up system by nephrologists was evaluated.

METHODS

A total of 427 living kidney donors underwent nephrectomy from January 2010 to December 2014 and were followed for at least 2 years at the Samsung Medical Center. Donors were followed-up by nephrologists after the establishment of a donor clinic with systemized protocols in January 2013. The primary outcomes were incidence of post-donation low estimated glomerular filtration rate (eGFR) and renal function adaptability. Secondary outcomes were changes in compliance and incidence of hyperuricemia and microalbuminuria.

RESULTS

The patients were divided into 2 groups according to the time of nephrectomy: the pre-donor clinic period (n = 182) and the donor clinic period (n = 172). Preoperative eGFR in patients in the pre-donor clinic period was higher than that in patients in the donor clinic period. After donation, poor renal adaptation was less frequent in the donor clinic period compared to the pre-donor clinic period. Low eGFR tended to be less common during the donor clinic period. Shorter mean outpatient clinic visit intervals with more visits within 6 months after donation and earlier detection of de novo hyperuricemia were found during the donor clinic period.

CONCLUSION

A protocolized donor clinic run by nephrologists may improve post-nephrectomy renal outcomes and compliance and facilitate better management of potential risk factors of chronic kidney disease in donors.

Chronic kidney disease as a cardiovascular risk factor: lessons from kidney donors

Chronic kidney disease (CKD) is a major risk factor for cardiovascular disease but is often associated with other risks such as diabetes and hypertension and can be both a cause and an effect of cardiovascular disease. Although epidemiologic data of an independent association of reduced glomerular filtration rate with cardiovascular risk are strong, causative mechanisms are unclear.

Living kidney donors provide a useful model for assessing the “pure” effects of reduced kidney function on the cardiovascular system. After nephrectomy, the glomerular filtration rate ultimately falls by about one-third so many can be classified as having chronic kidney disease stages 2 or 3. This prompts concern based on the data showing an elevated cardiovascular risk with these stages of chronic kidney disease. However, initial data suggested no increase in adverse cardiovascular effects compared with control populations. Recent reports have shown a possible late increase in cardiovascular event rates and an early increase in left ventricular mass and markers of risk such as urate and albuminuria. The long-term significance of these small changes is unknown. More detailed and long-term research is needed to determine the natural history of these changes and their clinical significance.

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Subjects with chronic kidney disease (CKD) have an elevated risk of cardiovascular disease.

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Kidney donors have a reduced glomerular filtration rate and biochemical changes similar to CKD subjects.

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Most studies of donors have not shown an elevated risk of death or cardiac disease.

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Donors have structural and functional cardiovascular changes similar to early CKD.

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The clinical significance of these changes is currently unknown.

Predictive Factors of Renal Adaptation After Nephrectomy in Kidney Donors

BACKGROUND

Despite compensatory hyperfiltration in remaining nephrons following donor nephrectomy, some donors show impaired renal adaptation and low estimated glomerular filtration rate (eGFR). We investigated the factors predicting early renal adaptation after nephrectomy and identified kidney donors at risk of inadequate renal adaptation.

METHODS

A total of 265 living kidney donors from 2010 to 2013 were retrospectively analyzed. Renal function was serially followed for 6 months after the operation. Regression analyses were performed to identify the independent predictors of low eGFR (eGFR <60 mL/min/1.73 m²) and impaired renal adaptation (%Modification of Diet in Renal Disease [MDRD] <66% of baseline eGFR).

RESULTS

A total of 148 donors belonged to the low eGFR group, and changes in eGFR (ΔeGFR) at postoperative (PO) 1 day and 1 month were identified as independent predictors of low eGFR. Impaired renal adaptation was related to age, ΔeGFR PO 2-3 days, and ΔeGFR PO 1 month. Early renal adaptation was associated with age, male gender, and residual kidney computerized tomography angiography (CTA) volume. The best sensitivity and specificity were obtained with a cutoff value of ΔeGFR 31 at PO 1 day and 1 month for predicting low eGFR and with a value of ΔeGFR 27 at PO 2-3 days and 1 month for predicting impaired renal adaptation.

CONCLUSIONS

Our study showed that the degree of early renal adaptation determines subsequent renal function in kidney donors. Closer monitoring and management may be required in old or male donors with small residual CTA kidney volume as well as donors with persistent ΔeGFR >27 within 1 month of nephrectomy.

Chronic kidney disease epidemiology collaboration equation accuracy in predicting peritoneal dialysis-delivered creatinine clearance

INTRODUCTION

Measuring total (residual kidney plus peritoneal) creatinine clearance (CrCl) with 24-h urine and dialysate collections is recommended for peritoneal dialysis (PD) adequacy evaluation. Prediction equations applied in this instance could simplify the approach. Cockcroft-Gault and modification of diet in renal disease (MDRD) four (MDRD-4) and six (MDRD-6) variables equations have been tested in this setting, and conflicting results have been reported. The Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation is currently considered to be more sensitive than the established equations for kidney function estimation. However, its performance in PD adequacy evaluation has not been studied. Our aim was to assess CKD-EPI equation's performance in predicting total measured CrCl (MCC) in PD patients.

MATERIAL AND METHODS

A group of 23 consecutive PD patients, male/female: 5/18, median age: 66 (32-91) years, median time on PD 32 (2-126) months, were enrolled in the study. All were treated by automated PD (APD). Sixteen out of twenty-three had residual renal function (RRF). MCC was determined from 24-h dialysate and urine collections and also predicted by Cockcroft-Gault, MDRD (4 and 6), and CKD-EPI equations.

RESULTS

CKD-EPI and MDRD-6 estimation results were similar to MCC (9.01 ± 3.90 and 9.54 ± 2.98 vs. 8.64 ± 3.75 mL/min/1.73 m(2) p = 0.49 and 0.09, respectively). Neither the presence nor the volume of residual urine affected the accuracy of prediction. Cockcroft-Gault and MDRD-4 equations differed significantly from MCC and were not accurately predictive.

CONCLUSION

CKD-EPI equation could be used with accuracy for predicting MCC in PD patients. Only MDRD-6 showed similar accuracy, whereas MDRD-4 and Cockcroft-Gault equations were found to be inappropriate in this setting.