Age and the associations of living donor and expanded criteria donor kidneys with kidney transplant outcomes

Abstract

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.

Figure 1

Distribution of age in 145,470 kidney transplant patients

Figure 2

Hazard ratios (95% confidence intervals) of all-cause mortality using Cox regression analyses in 145,470 kidney transplant patients (reference category: 18-<35 years)

Figure 3

Hazard ratios (95% confidence intervals) of death censored graft failure using Cox regression analyses in 145,470 kidney transplant patients (reference category: 18-<35 years)