Purpose: In the analysis of risk factors affecting the renal graft survival and graft function, time-dependent effect of each risk factor should be differentiated from net effect of risk factor. We attempted to analyze the impact of immunologic and/or non-immunologic risk factors on the graft function and survival after renal transplantation among the recipients having same immunologic risks at the time of transplantation.
Methods: Three hundred ninety recipients who underwent haplotype matched living related donor kidney transplantation and have been regularly followed-up were retrospectively evaluated in a single center. All recipients were treated with cyclosporine-based double or triple regimens. The graft function was evaluated by serum creatinine (Scr) level and 24 hours urinary excretion of protein every year until 5 years after transplantation. The donor kidney weight/ recipient body weight ratio (KW/BW), donor age/ recipient age ratio (DA/RA), donor-recipient sex (D-R sex) relationship, and episodes of acute rejection (AR) within 1 year were regarded as the potential risk factors affecting the graft survival and function in this study. Kaplan-Meier method and Cox proportional-hazard model were used for survival analysis. ANOVA to evaluate time-point difference of graft function, and repeated measures ANOVA to evaluate the yearly difference of graft function were used.
Results: Only the episode of AR was a significant risk factor affecting the graft survival. However, each non-immunologic risk factors (KW/BW, DA/RA, D-R sex) and AR episode persistently showed statistically significant impact on Scr level until 5 years after transplantation. Recipients having lowest KW/BW (1st Q KW/BW) and highest DA/RA (4th Q DA/RA) had experienced accelerated increment of Scr level from 4th year after transplantation. From 3rd year after transplantation, there is a significant correlation between the numbers of non-immunologic risk factor the recipients having had and yearly increment of Scr level. However, episode of AR didn’t influence the annual slope of Scr level even 4th year after transplantation.
Conclusion: Non-immunologic risk factors had an detrimental effect on renal graft function, especially from 3rd year after transplantation. To have a better long-term graft function, non-immunologic risk factors should be considered from the time of live donor evaluation for transplantation. From the early period of transplantation, the recipients should be aware of the negative impact of overweight in terms of graft function and other metabolic derangement.
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