A Higher Glomerular Filtration Rate Predicts Low Risk of Developing Chronic Kidney Disease in Living Kidney Donors

Abstract

The risk of developing chronic kidney disease (CKD) among living kidney donors (LKDs) is seldom included in evaluations of patients' outcomes. Potential risk factors and new criteria for estimating the glomerular filtration rate (eGFR) indexed for body surface area (BSA) were investigated with a view to prevent the development of CKD in LKDs. We conducted a retrospective study of LKDs from May 1983 to March 2011. The Mann-Whitney U test and χ(2) test were used to analyze the male versus female groups. Survival analysis was plotted as CKD-free survival and analyzed separately by different eGFR index classifications. The Cox regression model was used to identify potential risk factors for development of CKD. A total of 105 LKDs with a mean age of 46.3±12.5years had a mean eGFR indexed for BSA of 88.9±21.5ml/min per 1.73m(2). After a mean duration of 5.4±4.9years' follow-up, eGFR dropped to 61.4±16.4ml/min per 1.73m(2) (p=0.002). Median CKD-free survival was only 5.7years. The difference between eGFR≥80ml/min per 1.73m(2) and <80ml/min per 1.73m(2) was not statistically significant (p=0.980). Multivariate Cox regression analysis showed that higher eGFR at donation (HR=0.952, p=0.0199) could be a protective factor. The receiver operating characteristic (ROC) curve for initial eGFR with best sensitivity of 52.78% and specificity of 81.40% was obtained with a cutoff value of 90.2ml/min per 1.73m(2) for preoperative eGFR. An eGFR of 90ml/min per 1.73m(2) yielded a significant survival curve (p=0.0199) after 21years of follow-up. Further classifications of eGFR >90ml/min per 1.73m(2) into 90-99ml/min per 1.73m(2), 100-109ml/min per 1.73m(2), and ≥110ml/min per 1.73m(2) were examined, but this survival curve was not statistically significant (p=0.1247). Living kidney donors will develop CKD after a long duration of follow-up if there is insufficiently high eGFR at donation. An eGFR above 90ml/min per 1.73m(2) before donation is the only factor that predicts prevention of CKD. Larger studies with longer duration of follow-up are necessary to clarify the clinical outcome of this postoperative CKD group, especially for patients with eGFR between 80 and 90ml/min per 1.73m(2).