BACKGROUNDThe status of sensitization in kidney transplant recipients in the last 10 years and the trend of induction and maintenance therapy in patients of different panel-reactive antibody (PRA) levels have not been analyzed. The aim of this study was to investigate the current status of pre-transplant sensitization and its association with graft outcome.

METHODSA total of 155 570 kidney transplants reported to United Network for Organ Sharing (UNOS) during 2000 - 2009 were included in this study. We investigated the current status of pre-transplant sensitization and its association with graft outcome, and also compared the usage trend of 16 induction agents and 7 maintenance immunosuppressants in patients at different PRA levels. The difference of distributions of categorical variables between groups was investigated using the chi-square test. Unpaired t test or one-way analysis of variance (ANOVA) were used for numerical variables. The survival rates of transplant recipients were estimated using Kaplan-Meier methods and significance was determined by Log-rank test. Two-side P value < 0.05 was considered statistically significant. All statistical analyses were performed using STATA 10 with all available updates as of March 2010 (StataCorp LP, College Station, Texas 77845, USA).

RESULTSDespite the fact of the decreased percentages of kidney transplant recipients with presensitization history, the mean PRA levels of all kidney recipients has been increasing in the last 7 years, which was possibly due to the introduction of more sensitive antibody testing techniques. The percentage of patients with treated rejection episodes within one year post-transplant were significantly higher in sensitized patients (PRA = 50% - 100%:14.3% and PRA = 1% - 49%:13.9%) than in non-sensitized patients (12.4%). Both 1- and 5-year graft survival rates improved in the last 10 years; this was more significant in high PRA patients. Thymoglobulin was the most commonly used induction agent in last 10 years. Its users increased from 10% to 46% in non-sensitized patients, from 12% to 57% in PRA 1% - 49% patients, and from 19% to 63% in PRA 50% - 100% patients. The users of Campath, intravenous immunoglobulin (IVIG), and Rituximab have been increasing and reached 16%, 20%, and 11% in highly sensitized patients. In the last 5 years, steroid-free patients were 33% - 36%, 30% - 37%, and 10% - 25% for PRA 0, 1% - 49%, and 50% - 100% respectively. Almost 90% of patients were on Prograf at discharge. It seems that Myfortic users have been increasing since 2005 and it may soon replace mycophenolate mofetil (MMF) if long-term follow-up study conforms its safety and efficacy.

CONCLUSIONSApplication of sensitive antibody testing techniques increased the mean PRA levels of transplant recipients in spite of a decreased percentage of sensitized recipients. Induction and maintenance therapy differed in patients at different PRA levels.