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John Armitage, Helen L. Winton, Mark N. Jones, Chris A. Rogers, Jeff L. Bidwell, Derek M. Tole, Andrew D. Dick; Corneal Transplant Follow-up Study II (CTFS II): Patient Baseline Characteristics And Influence Of Recipient Age On Risk Of Rejection. Invest. Ophthalmol. Vis. Sci. 2012;53(14):2385. doi: https://doi.org/.
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Allograft rejection remains a major cause of corneal transplant failure. The Corneal Transplant Follow-up Study II (CTFS II) is a prospective, multicentre clinical trial to investigate the influence of HLA class II matching in high risk penetrating keratoplasty (PK). This paper presents the baseline characteristics of the transplants included in the study and reports a reduced risk of rejection with increasing recipient age.
1130 high risk PKs have been accrued to the study. All were matched for HLA class I and allocated to the three study groups of 0, 1 or 2 HLA-DR mismatches by cohort minimization. Donors andrecipients were HLA typed by DNA methodology to avoid the inherent errors in serological typing. Patients were followed up at 6 months and then annually to 5 years. Time to first rejection was the primary outcome. An interim analysis was carried out on 776 transplants with 2 year follow up. Rejection-free survival was estimated by the Kaplan-Meier method and compared between groupsusing Cox proportional hazards regression.
Overall, regraft was the most frequent indication contributing almost 45% of transplants to the study. This was followed by bullous keratopathy with 21% of transplants. Of the preoperative risk factors, 60% of corneas were vascularized, 21% of eyes had glaucoma and 22% had inflammation or infection. 18% of transplants were fully matched for HLA-DR while 46% and 36% had, respectively, 1 or 2 HLA-DR mismatches. In the interim analysis, 74% of patients (95% CI 71-77, n=776) were rejection-free at 2 years. There was a marked, albeit time-dependent, influence of recipient age on freedom from rejection at 2-years, which varied from 66% (95% CI 56-74, n=112) for recipients ≤40 years old to 86% (95% CI 77-92, n=110) for recipients >80 years old (p=0.0003).
Recruitment to CTFS II has now closed. Final analysis of the influence of HLA class II matching on risk of allograft rejection will take place when 5-year follow up has been completed for alltransplants. The marked influence of recipient age on risk of rejection observed in the interim analysis suggests that purported age-related changes in the immune system, such as reduced numbers of dendritic cells and reduced ability of generate naïve T-cells, render older recipients less prone to corneal allograft rejection than younger recipients.
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