Original Investigation
Transplantation
Age and the Associations of Living Donor and Expanded Criteria Donor Kidneys With Kidney Transplant Outcomes

https://doi.org/10.1053/j.ajkd.2011.12.014Get rights and content

Background

Recent studies show a survival advantage with kidney transplant in elderly patients compared with those on dialysis therapy.

Study Design

In our present study, we examined and compared the association of expanded criteria donor (ECD) kidney and living kidney donation with the outcome of kidney transplant across different ages, including elderly recipients.

Setting & Participants

Using the Scientific Registry of Transplant Recipients, we identified 145,470 adult kidney transplant patients. Mortality and death-censored transplant failure risks were estimated by Cox proportional regression analyses during follow-up with a median of 3.9 years.

Predictors

ECD kidney and living kidney donation and age compared with others.

Outcomes

Mortality and death-censored transplant failure risk.

Results

Patients were aged 45 ± 16 years and included 40% women and 19% patients with diabetes. Compared with transplant recipients 55 to younger than 65 years, the fully adjusted death-censored transplant failure risk was higher in patients 75 years and older (HR, 1.30; 95% CI, 1.09-1.56), 35 to younger than 55 years (HR, 1.13; 95% CI, 1.08-1.17), and 18 to younger than 35 years (HR, 1.64; 95% CI, 1.57-1.71). Compared with non-ECD kidneys, ECD kidneys were significant predictors of mortality in nonelderly patients (18-<35 years: HR, 1.46 [95% CI, 1.19-1.77]; 35-<55 years: HR, 1.23 [95% CI, 1.14-1.32]; and 55-<65 years: HR, 1.26 [95% CI, 1.15-1.38]) and patients 65 to younger than 70 years (HR, 1.20; 95% CI, 1.05-1.36), but not in other groups of elderly patients (HRs of 1.12 [95% CI, 0.93-1.36] for 70-<75 years and 1.04 [95% CI, 0.74-1.47] for ≥75 years). Similar results were found for risk of transplant loss. Compared with deceased donor kidneys, a living donor kidney was associated with better survival in all age groups and lower transplant loss risk in patients younger than 70 years.

Limitations

Unmeasured confounders cannot be adjusted for.

Conclusions

For deceased donors, ECD kidneys are not associated with increased mortality or transplant failure in recipients older than 70 years. For all types of donors, the persistent association between living donor kidneys and lower all-cause mortality across all ages suggests that, if possible, elderly patients gain longevity from living donor kidney transplant.

Section snippets

Patients

We extracted, refined, and examined data from all kidney transplant recipients listed in the SRTR up to December 2006. The SRTR data system includes data for all transplant donors, wait-listed candidates, and transplant recipients in the United States, which are submitted by members of the Organ Procurement and Transplantation Network. This study was approved by the Institutional Review Committees of Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center. Because of the large

Results

Using the SRTR database, we identified 145,470 adult kidney transplant recipients. There were 25,616 deaths (18%) and 22,876 transplant failures (16%). Median follow-up was 1,449 (25th-75th percentile, 636-2,497) days. Figure 1 shows the age distribution of the 145,470 kidney transplant patients. Only 11% of patients were older than 65 years. Table 1 lists clinical, demographic, laboratory, and transplant data for the 145,470 kidney transplant patients across 6 different age groups, including 3

Discussion

In 145,470 kidney transplant recipients, older age was associated with an incrementally higher risk of death. The association between age and death-censored transplant failure was U-shaped, indicating the highest risk of transplant failure in both young adults (18-<35 years) and very old patients (≥75 years) and the lowest risk in patients aged 55 to younger than 75 years. In patients older than 70 years, ECD kidney was not a significant predictor of death or transplant loss. However, in

Acknowledgements

The findings of this manuscript were included in an oral presentation during the American Society of Nephrology (ASN) Kidney Week, November 8-13, 2011, Philadelphia, PA.

We acknowledge the SRTR for providing the database for this research.

Support: The study was supported by research grant 0655776Y from the American Heart Association to Dr Kalantar-Zadeh. Dr Kalantar-Zadeh's other funding sources include the National Institute of Diabetes, Digestive and Kidney Diseases of the National Institutes

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      Transplantation of donor kidneys aged ≥65 years has been associated with decreased recipient and graft survival, although outcomes remained superior compared with remaining on dialysis [20,21]. It has been previously reported that elderly recipients of ECD kidneys have similar patient and graft survival rates compared with elderly recipients of non-ECD kidneys [22]. However, the similar rejection rates we observed when comparing elderly and younger recipients of deceased donor kidneys is an unexpected finding and may be related to the high proportion of lower quality kidneys transplanted into the elderly group.

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    Originally published online February 10, 2012.

    M.Z.M. and E.S. contributed equally to this work.

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