Impact of intra-patient variability of tacrolimus on allograft function and CD4 + /CD8 + ratio in kidney transplant recipients: a retrospective single-center study.

Background: Tacrolimus is a critical component of immunosuppressive therapy for kidney transplant recipients. Intra-patient variation (IPV) of tacrolimus levels affects the function of transplanted kidney.

Aim: This study aimed to investigate the impact of tacrolimus IPV on kidney function, examine its association with post-transplant duration, and assess its effect on the immune status of transplant recipients.

Method: This retrospective study was conducted from January 2016 to February 2022. IPV was evaluated using the coefficient of variation (CV) of tacrolimus trough levels from 6 to 48 months after transplantation. Patients were divided into low- and high-IPV groups based on the median CV. Significant differences in kidney function, CD4 + /CD8 + ratio, and post-transplant duration between these groups were analyzed.

Results: Among 189 patients, tacrolimus IPV showed a strong correlation with serum creatinine clearance rate (Ccr) and estimated glomerular filtration rate (eGFR) (p < 0.05). Tacrolimus IPV was significantly correlated with post-transplant duration in only two patients (p < 0.05). Using a median CV of 15.4% to categorize patients, the high IPV group, compared to the low IPV group, exhibited significantly higher eGFR at 6-9 months (p < 0.05), lower Ccr at 9-12 months (p < 0.05), and reduced Ccr and eGFR at 15-18 months (p < 0.05). Six months after transplantation, the high IPV group had a significantly lower CD4 + /CD8 + ratio than the low IPV group (p < 0.05).

Conclusion: This study highlights the significant impact of tacrolimus IPV on transplant kidney function and immune status in transplant patients at various post-transplantation intervals.