The effect of donor age on corneal transplantation outcome results of the cornea donor study

Abstract

Objective: To determine whether graft survival over a 5-year follow-up period using corneal tissue from donors older than 65 is similar to graft survival using corneas from younger donors.

Design: Multicenter prospective, double-masked, controlled clinical trial.

Participants: One thousand ninety subjects undergoing corneal transplantation for a moderate-risk condition (principally Fuchs' dystrophy or pseudophakic corneal edema); 11 subjects with ineligible diagnoses were not included.

Methods: Forty-three participating eye banks provided corneas from donors in the age range of 12 to 75 with endothelial cell densities of 2300 to 3300 cells/mm(2), using a random approach without respect to recipient factors. The 105 participating surgeons at 80 sites were masked to information about the donor cornea including donor age. Surgery and postoperative care were performed according to the surgeons' usual routines. Subjects were observed for 5 years.

Main outcome measures: Graft failure, defined as a regraft or a cloudy cornea that was sufficiently opaque as to compromise vision for a minimum of 3 consecutive months.

Results: The 5-year cumulative probability of graft survival was 86% in both the <66.0 donor age group and the >/=66.0 donor age group (difference = 0%, upper limit of 1-sided 95% confidence interval = 4%). In a statistical model with donor age as a continuous variable, there was no significant relationship between donor age and outcome (P = 0.11). Three graft failures were due to primary donor failure, 8 to uncorrectable refractive error, 48 to graft rejection, 46 to endothelial decompensation (23 of which had a prior, resolved episode of probable or definite graft rejection), and 30 to other causes. Distributions of the causes of graft failure did not differ between donor age groups.

Conclusions: Five-year graft survivals for cornea transplants at moderate risk for failure are similar using corneas from donors >/= 66.0 years and donors < 66.0. Surgeons and patients now have evidence that corneas comparable in quality to those used in this study from donors through age 75 are suitable for transplantation.

Figure 1 (on line)

Flow chart of follow up in the older and younger donor age groups

Figure 2

Graft success by donor age group over time. For purposes of analysis, all failure or censoring events within the 5-year visit window (58 to 66 months) were mapped to month 60. The number of graft failures during the interval in parenthesis represents graft failures due to endothelial decompensation. CI is confidence interval.

Figure 3 (on line)

Survival Difference between Donor Age Groups by Sequential Donor Age Cutoff Groups. Each donor age value on the y-axis marks the cutoff for two age groups (e.g. 35 donor age cutoff value divides the cohort into two donor age groups: <35 years and ≥35 years), for which the survival difference is calculated. The survival difference estimate (represented by a dot in the figure, with the line representing the pointwise 99% confidence interval) is calculated by subtracting the Kaplan-Meier survival estimate in the older donor age group from the survival estimate in the younger donor age group. Positive survival difference indicates greater survival in the younger donor age group. The first cut point used for the analyses is at age 25 because of the small number of donors less than 25 years of age.

Figure 4 (on line)

Five-year Graft Status by Donor Age. The category “Graft Success” includes subjects who completed the 5-year examination; the category “Graft Failure” includes subjects who experienced graft failure within 5 years after surgery; the category “Incomplete Follow Up” includes subjects who died, withdrew, were lost to follow up prior to the end of the 5-year window, or did not complete a 5-year exam.