Estimated GFR for Living Kidney Donor Evaluation

Area of Science:

• Nephrology
• Transplantation
• Medical Diagnostics

Background:

• Living kidney donor candidates require Glomerular Filtration Rate (GFR) evaluation.
• Current guidelines recommend measured GFR (mGFR) over estimated GFR (eGFR).
• mGFR methods are often impractical due to cost, time, and complexity.

Purpose of the Study:

• To assess the accuracy of eGFR (using serum creatinine and cystatin C) in identifying living kidney donor candidates with a high probability of meeting specific mGFR thresholds.
• To determine if eGFR can reliably predict whether mGFR is above or below critical values for clinical decision-making in donor selection.
• To reduce the reliance on costly and time-consuming mGFR measurements in donor candidate evaluations.

Main Methods:

• Combined pretest probabilities of mGFR thresholds (using National Health and Nutrition Examination Survey demographic data) with eGFR test performance (likelihood ratios from CKD-EPI).
• Calculated posttest probabilities for mGFR status based on eGFR values.
• Utilized data from the Scientific Registry of Transplant Recipients for analysis.
• Developed a web-based application for probability computation.

Main Results:

• 53% of recent living kidney donors had an eGFRcr value indicating a ≥95% probability that their mGFR was ≥90 mL/min/1.73 m².
• This suggests that mGFR may be unnecessary for a significant proportion of potential living kidney donors.
• The study provides a method to calculate the probability of a donor candidate's mGFR being above or below key thresholds.

Conclusions:

• eGFR, particularly eGFRcr, can be sufficiently accurate to identify living kidney donor candidates where mGFR is likely to be above critical thresholds.
• The findings support the potential to reduce the need for mGFR in many donor candidates, simplifying the evaluation process.
• A web-based tool was developed to aid clinicians in probability assessment for donor selection based on eGFR.