Higher Risk of Kidney Failure in Older Donors With Hypertension

Veronica Hackethal, MD

June 25, 2019

Older kidney donors with hypertension had a higher 15-year risk of end-stage renal disease (ESRD) compared with donors of the same age without hypertension, according to a new US study published today in the Clinical Journal of the American Society of Nephrology.

The study is the largest to date to examine what risks older donors with hypertension may face in the long term, say researchers, and provides new information that may help inform discussions with older people when they consider donating a kidney.

Although the total number of people who developed ESRD was small, the difference between older donors with or without hypertension was significant. The results suggest older individuals with predonation hypertension have about a threefold increased risk for ESRD over 15 years. Both groups had a similar 15-year risk of death.

"Albeit a rather small risk, practice guidelines for live kidney donor evaluation need to be revisited," said lead author Fawaz Al Ammary, MD, PhD, Johns Hopkins University, Baltimore, Maryland, in a press release by the American Society of Nephrology.

"While controlled hypertension in otherwise eligible older individuals may not be viewed as an absolute contraindication for kidney donation, these findings may inform conversations between the provider and the older individuals with hypertension when they consider donating a kidney," Al Ammary added.

In an accompanying editorial, Kenneth Newell, MD, PhD, Emory University, Atlanta, Georgia, and Richard Formica, MD, Yale University, New Haven, Connecticut, write: "The findings of Ammary et al represent an incremental but yet significant step toward better understanding the risks of ESRD for an expanding cohort of medically complex living kidney donors."

Kidney Donation Rising Among Older Population

Over the last decade, kidney donation among individuals aged 50 years and older has jumped more than 50%, according to background information in the article.

Receiving a kidney from a living donor is the best treatment for patients with kidney failure, and donations from older individuals can increase the donor pool, especially for older individuals in need of a transplant who may not survive long enough for a nonliving donor transplant.

But it is important to ensure individuals who wish to donate an organ are able to safely do so, the researchers stress.

Many older donors may have age-related conditions, such as hypertension, and although past research has suggested kidney donation among older individuals with hypertension is safe, long-term outcomes have remained unclear.

To investigate this further, researchers used linked data from Medicare, the Social Security death registry, and national transplant registry to compare kidney donors aged 50 and over with hypertension to donors in the same age group without hypertension, to examine 15-year outcomes of risk of ESRD and death.

The US study included 24,533 individuals who donated kidneys between 1999 and 2016. Of these, 9% (n = 2265) had hypertension at time of donation and an average predonation blood pressure of 138/80 mmHg. Overall, the study group was 82% white, 6% black, 7% Hispanic, and 3% Asian.

For the period 2004-2016, researchers also defined hypertension as predonation use of antihypertensive medication. Because documentation of antihypertensive medication was not available in 1999-2003, they defined hypertension during this period as predonation systolic blood pressure ≥ 140 mmHg or diastolic pressure ≥ 90 mmHg.

Sixfold Higher ESRD Risk in Those on BP Meds at Time of Donation

Over a median follow-up of 7.1 years (maximum 18 years), 24 participants developed ESRD and 252 died.

Older individuals with predonation hypertension had a higher 15-year incidence of ESRD than those without hypertension (0.8% vs 0.2%).

After adjusting for age, sex, race, estimated glomerular filtration rate (eGFR), and biological relationship to the recipient, individuals with predonation hypertension had a 15-year risk of ESRD that was three times higher than donors without predonation hypertension (hazard ratio [HR], 3.04; 95% CI, 1.28 - 7.22; P = .01).

Analyses restricted to the time period when data on antihypertensive medication was available (2004-2016) showed an even stronger association.

Individuals on antihypertensives at the time of donation had an over sixtimes increased risk of ESRD compared with those not on antihypertensives (HR, 6.21; P = .03). 

However, donors with and without hypertension had a similar incidence of mortality (unadjusted 15-year cumulative incidence, 3.5% vs 2.5%; P = .06; adjusted HR, 1.18; P = .34).

And results for ESRD and death were unchanged after adjusting for obesity.

The authors mention several study limitations, including there were no data on albumin levels, so researchers could not determine whether some individuals had underlying kidney disease at the time of donation.

Education, Lifelong Access to Care for Older Donors With High BP

In their editorial, Newell and Formica stress that although the absolute risk of kidney disease in older individuals with predonation hypertension was low in this study, providers who counsel those contemplating live kidney donation should address several issues with their patients.

These include comprehensive education about the long-term risks of kidney donation and lifelong access to medical care for early detection and optimal treatment of kidney disease and related medical conditions if they develop.

"The findings of this study should not be used to 'allow' or 'exclude' individuals from proceeding with living kidney donation but rather should be incorporated into a comprehensive educational program to better inform donors about the long-term consequences of their decision to be a living kidney donor," they conclude.

The authors have reported no relevant financial relationships.

CJASN. Published online June 25, 2019.

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