Long-Term Renal Function of Living Kidney Donors- A Prospective Cohort Study.

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Introduction and Aims: The long-term medical risks after living kidney donation are uncertain. This study aimed to determine the factors that predict long-term post-donation decline in renal function amongst living kidney donors. Methods: A longitudinal analysis was undertaken within a prospective cohort of living donors (n=357, aged above 22.2 years) donated in a single centre between January 2000 and December 2013. The change in estimated glomerular filtration rate (eGFR) between baseline (pre-donation), one, five and ten years was analysed using multilevel mixed model analyses. The glomerular filtration rate was estimated using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) formula. Results: Of the 357 living donors, 338 (94.7%) completed follow-up at the first year. A total of 138 (out of 237, 58.2%) and 48 (out of 88, 54.5%) were followed at five and ten years, respectively. The mean eGFR at baseline, one, five and ten years were 94 ml/min/1.73m2 (SD: 13.97), 61 (SD: 12.45), 58 (SD: 12.81) and 56 (SD: 12.67). Overall, eGFR declined by 32.7 (SD: 10.7) ml/min/1.73m2 between baseline and one year in participants who had repeated measures of serum creatinine (323 out of 357, 90.5%). The decline in eGFR stabilised between 1-5 and 5-10 years after donation, with a median reduction in eGFR of 0.47 (SD: 6.1) ml/min/1.73m2 and 0.81 (SD: 3.1) ml/min/1.73m2, respectively. Multivariate linear mixed modelling suggested that older age and higher body mass index (BMI) at the time of donation were associated with the greatest annual decline in eGFR post-nephrectomy (p values <0.001 and 0.02 respectively). There was a 0.57 ml/min/1.73m2 per year reduction in eGFR for every year increase in age at the time of donation. For every 1 kg/m2 increase in BMI at the time of donation, there was a 0.70 ml/min/1.73m2 reduction in eGFR annually over the 10-year follow-up. There was an insufficient number of donors with pre-existing hypertension and/or albuminuria to assess an effect on eGFR. Conclusion: Older age and higher BMI at the time of donation are independent predictors of decline in renal function over time amongst living kidney donors. However, the absolute decrement of renal function appeared to remain stable with aging.