Kidney Donation Linked to Increased Risk of Hypertension

A recent study from Johns Hopkins University found that donating a kidney increased the chance of developing hypertension by 19% in donors and that risk increased to 27% in black donors.

In addition to increasing a patient’s risk of hypertension regardless of race, results also revealed improvement in kidney function plateaued in donors after the development of hypertension.

In an effort to assess the risk of hypertension in living kidney donors, investigators designed a cohort study that examined rates of hypertension and long-term eGFR in donors and healthy non-donors. Information on nondonor participants was taken from the Atherosclerosis Risk in Communities (ARIC) cohort and the Coronary Artery Risk Development in Young Adults (CARDIA) cohort, which investigators noted were both national cohort studies. Information on donors was obtained from the Wellness and Health Outcomes in the Live Donor study, which is a multicenter study that included at least 2 year of post donation follow-up on donors.

In total, the current study included a population of 1295 kidney donors and 8233 healthy non-donors. Investigators noted within the study there was apparent differences among the study cohorts but they were mitigated by the study’s weighting strategy. Additionally, kidney donors had a median of 6 post-donation eGFR measurements reported over a median of 6 years while non-donors had a median of 5 eGFR measurements over a median of 23 years.

Upon analyses, investigators found kidney donors had a higher incidence of hypertension than non-donors and this risk was greater in black donors compared to white donors. At 15 years, 8% of white non-donors and 9% of black non-donors had developed hypertension compared to 23% of white donors and 42% of black donors.

In an adjusted analysis, investigators calculated kidney donation was associated with a 19% higher risk of developing hypertension (aHR, 1.19; 95% CI, 1.01 to 1.41; P=0.04), regardless of race. In black patients, donation was associated with a 27% higher risk of developing hypertension (aHR 1.27l 95% CI, 1.13 to 1.42; P<0.001). Investigators noted that association between kidney donation did not vary by race (interaction P=0.60).

Among non-donors, a decline in eGFR was observed overtime. In white nondonors there was a mean yearly decline in eGFR (20.38 ml/min per 1.73 m2; 95% CI, 20.41 to 20.35 ml/min per 1.73 m2) that increased with incident hypertension (20.76 ml/min per 1.73 m2; 95% CI, 20.90 to 20.62 ml/min per 1.73 m2 per year; P<0.001 for difference after incident hypertension).

A similar effect was noted among healthy black nondonors with a mean yearly decline (20.32 ml/min per 1.73 m2; 95% CI, 20.38 to 20.25 ml/min per 1.73 m2) that steepened after incident hypertension (20.91 ml/min per 1.73 m2 ; 95% CI, 21.20 to 20.62 ml/min per 1.73 m2 per year; P<0.001 for difference after incident hypertension).

In regard to donors, investigators observed an increase in mean eGFR overtime regardless of race. In white donors, there was a mean yearly increase following donation of +0.42 2 (95% CI, +0.34 to +0.50) ml/min per 1.73 m2, but this plateaued after incident hypertension (mean change per year with hypertension, 0.00; 95% CI, 20.45 to +0.45 ml/min per 1.73 m2 ; P=0.07 for difference after incident hypertension).

A similar effect was found among black donors, who had a mean yearly increase in eGFR after donation of +0.64 (95% CI, +0.36 to +0.92) ml/min per 1.73 m2, but this plateaued after incident hypertension (mean change per year with hypertension, 20.20; 95% CI, 20.72 to +0.33 ml/min per 1.73 m2; P=0.01 for difference after incident hypertension).

In a related editorial, William Asch MD, PhD, of the Yale University School of Medicine, wrote if the findings could be corroborated within future studies they could change the way physicians view the safety of living with kidney donation.

“The findings presented by Holscher et al. are anticipated to have a meaningful effect on the transplant community across multiple dimensions, including the informed consent process, and policy decisions regarding obligations for the parent center to provide truly long-term (decades) follow-up for their living donors,” Asch wrote. “These findings also have the potential to further shift the public and media’s perception of the safety of living kidney donation.”

This study, “Self-Reported Incident Hypertension and Long-Term Kidney Function in Living Kidney Donors Compared with Healthy Nondonors,” was published online in CJASN.