Arteriosclerosis in zero-time biopsy is a risk factor for tacrolimus-induced chronic nephrotoxicity.

Calcineurin inhibitors reduce the acute rejection rate and greatly improve renal allograft survival. However, they are associated with some adverse events, including nephrotoxicity, a risk factor for allograft failure. Chronic calcineurin inhibitor-induced nephrotoxicity causes irreversible damage to renal components, such as arteriolar hyaline thickening. The aim of this study is to investigate the risk factors for tacrolimus-induced chronic nephrotoxicity using zero-time biopsy specimens. Between January 2001 and December 2010, 483 patients who underwent living-related kidney transplantation and had also been placed on a tacrolimus-based regimen were enrolled in this study. There were 1859 specimens evaluated comprising 483 zero-time biopsy specimens and 1376 protocol and for-cause biopsy specimens. De novo arteriolar hyaline thickening due to tacrolimus-induced chronic nephrotoxicity was scored according to the Banff classification aah score. In this study, tacrolimus-induced nephrotoxicity was defined as a positive aah score. Of the 483 patients, 108 patients (22.4%) had biopsy-proven tacrolimus-induced chronic nephrotoxicity. Multivariate analysis showed that interlobular arteriosclerosis proven by zero-time biopsy (OR: 2.23, 95%CI: 1.38-3.58, P < 0.01) and acute rejection episodes (OR: 1.58, 95%CI: 1.00-2.47, P = 0.04) were independent risk factors for tacrolimus-induced chronic nephrotoxicity. However, tacrolimus-induced chronic nephrotoxicity did not affect long-term graft survival. This is the first report showing that arteriosclerosis in zero-time biopsy specimens is a risk factor for histological tacrolimus-induced chronic nephrotoxicity.