Risk of Kidney Stones in Living Kidney Donors
Risk of Kidney Stones in Living Kidney Donors
A kidney stone in a person with a solitary kidney requires urgent attention, which may result in surgical and/or hospital attention. We conducted a matched retrospective cohort study to determine if living kidney donors compared to healthy nondonors have a higher risk of: (i) kidney stones with surgical intervention, and (ii) hospital encounters for kidney stones. We reviewed all predonation charts for living kidney donations from 1992 to 2009 at five major transplant centers in Ontario, Canada, and linked this information to healthcare databases. We selected nondonors from the healthiest segment of the general population and matched 10 nondonors to every donor. Of the 2019 donors and 20 190 nondonors, none had evidence of kidney stones prior to cohort entry. Median follow-up time was 8.4 years (maximum 19.7 years; loss to follow-up <7%). There was no difference in the rate of kidney stones with surgical intervention in donors compared to nondonors (8.3 vs. 9.7 events/10 000 person-years; rate ratio 0.85; 95% confidence interval [CI] 0.47–1.53). Similarly there was no difference in the rate of hospital encounters for kidney stones (12.1 vs. 16.1 events/10 000 person-years; rate ratio 0.75; 95% CI 0.45–1.24). These interim results are reassuring for the safety of living kidney donation.
Every year, over 27 000 individuals worldwide choose to undergo living kidney donation to help someone in need. Knowledge of the long-term outcomes of living kidney donors is required to maintain public trust in the transplantation system, inform the choices of potential donors and recipients, and guide the follow-up care necessary to maintain optimal long-term health.
One outcome that remains poorly understood in past living kidney donors is the subsequent development of kidney stones. In September 2012, we performed a detailed search of bibliographic databases (PubMed, Google Scholar) and found only a few reports of living kidney donors being treated for kidney stones at the time of nephrectomy. However, these studies did not report the rate or long-term risk of kidney stones in this unique population. We expanded the search to include kidney stones in those with a solitary kidney for any reason and again found only literature discussing the management of the stone at the time of its occurrence.
In the general population, kidney stones are common with an estimated lifetime risk of 10–15%. Most stones are small and pass through the urinary tract spontaneously within 4 weeks of initial symptoms. However, some stones may require surgical intervention including shockwave lithotripsy, ureteroscopy or percutaneous nephrolithotomy. There is no reason to suspect that living kidney donors would have a higher risk of kidney stones than members of the general population. Yet, a kidney stone in an individual with a solitary kidney can potentially obstruct the ureter, leading to acute renal failure, and may result in urgent hospital attention and even surgical intervention. This is also a concern because kidney stones can result in a decline in renal function, and this risk may be even higher in donors compared to nondonors. We conducted this matched retrospective cohort study to determine if living kidney donors compared to healthy nondonors have a higher risk of: (i) kidney stones with surgical intervention, and (ii) hospital encounters for kidney stones.
Abstract and Introduction
Abstract
A kidney stone in a person with a solitary kidney requires urgent attention, which may result in surgical and/or hospital attention. We conducted a matched retrospective cohort study to determine if living kidney donors compared to healthy nondonors have a higher risk of: (i) kidney stones with surgical intervention, and (ii) hospital encounters for kidney stones. We reviewed all predonation charts for living kidney donations from 1992 to 2009 at five major transplant centers in Ontario, Canada, and linked this information to healthcare databases. We selected nondonors from the healthiest segment of the general population and matched 10 nondonors to every donor. Of the 2019 donors and 20 190 nondonors, none had evidence of kidney stones prior to cohort entry. Median follow-up time was 8.4 years (maximum 19.7 years; loss to follow-up <7%). There was no difference in the rate of kidney stones with surgical intervention in donors compared to nondonors (8.3 vs. 9.7 events/10 000 person-years; rate ratio 0.85; 95% confidence interval [CI] 0.47–1.53). Similarly there was no difference in the rate of hospital encounters for kidney stones (12.1 vs. 16.1 events/10 000 person-years; rate ratio 0.75; 95% CI 0.45–1.24). These interim results are reassuring for the safety of living kidney donation.
Introduction
Every year, over 27 000 individuals worldwide choose to undergo living kidney donation to help someone in need. Knowledge of the long-term outcomes of living kidney donors is required to maintain public trust in the transplantation system, inform the choices of potential donors and recipients, and guide the follow-up care necessary to maintain optimal long-term health.
One outcome that remains poorly understood in past living kidney donors is the subsequent development of kidney stones. In September 2012, we performed a detailed search of bibliographic databases (PubMed, Google Scholar) and found only a few reports of living kidney donors being treated for kidney stones at the time of nephrectomy. However, these studies did not report the rate or long-term risk of kidney stones in this unique population. We expanded the search to include kidney stones in those with a solitary kidney for any reason and again found only literature discussing the management of the stone at the time of its occurrence.
In the general population, kidney stones are common with an estimated lifetime risk of 10–15%. Most stones are small and pass through the urinary tract spontaneously within 4 weeks of initial symptoms. However, some stones may require surgical intervention including shockwave lithotripsy, ureteroscopy or percutaneous nephrolithotomy. There is no reason to suspect that living kidney donors would have a higher risk of kidney stones than members of the general population. Yet, a kidney stone in an individual with a solitary kidney can potentially obstruct the ureter, leading to acute renal failure, and may result in urgent hospital attention and even surgical intervention. This is also a concern because kidney stones can result in a decline in renal function, and this risk may be even higher in donors compared to nondonors. We conducted this matched retrospective cohort study to determine if living kidney donors compared to healthy nondonors have a higher risk of: (i) kidney stones with surgical intervention, and (ii) hospital encounters for kidney stones.
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