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Atopic keratoconus patients undergoing PK had higher graft rejection rate
Cornea. 2009;28(8):846-850.
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Keratoconus patients with atopy had a higher incidence of corneal graft rejection after penetrating keratoplasty than non-atopic patients, but the difference was statistically insignificant, according to a study.
Additionally, the characteristics of graft rejection in atopic patients did not vary significantly from those in non-atopic patients, the study authors said.
The retrospective study included 75 patients who underwent PK and completed a questionnaire on personal atopic history. Subjects were assigned to three groups: non-atopic (13 patients), mildly atopic (36 patients) and severely atopic (26 patients).
Investigators reviewed incidence and characteristics of graft rejection but were shielded to patient history of graft rejection.
The incidence of graft rejection (episodes per 100 person-years) was 7.3% in the non-atopic group, 15.8% in the mildly atopic group and 13.4% in the severely atopic group.
The graft rejection rate of mildly and severely atopic patients approximately doubled that of non-atopic patients. However, the differences between the groups were not statistically significant.
At 37.1 years, mildly atopic patients had a significantly lower mean age (P = .004) at the time of surgery and a significantly higher rate of bilateral keratoplasty (P = .01) than those in the other groups.
Sixty-nine percent of first graft rejection episodes were mild or moderate in mildly atopic patients; 94% of episodes were mild or moderate in severely atopic patients. Fifty percent of episodes were severe in non-atopic patients. However, the differences between the groups were statistically insignificant, the authors said.
This study suggests that among keratoconus patients undergoing penetrating keratoplasty the likelihood of graft rejection may depend on the presence and severity of atopy. However, interpretation of this study’s results must be undertaken with caution; when the difference in outcomes among patient groups (non-atopic, mildly atopic and severely atopic) was corrected for patient age and bilaterality of surgery, the P value was greater than 0.54. In other words, there is a 54% chance that the difference in the rate of graft rejection between groups was purely a matter of chance rather than a true relationship between atopy and rejection.
– John A. Hovanesian, MD
OSN
Cornea/External Disease Board Member