Low early posttransplant serum tacrolimus levels are associated with poor patient survival in lung transplant patients

BACKGROUND: Low-dose tacrolimus-based immunosuppression is a standard therapy in kidney and liver transplantation; however, the optimal therapeutic level of tacrolimus has not been established in lung transplantation. We aimed to identify the tacrolimus level associated with better outcomes in lung transplant patients. METHODS: This retrospective study included patients who underwent lung transplantation at Seoul National University Hospital between 2006 and 2016. Kaplan-Meier survival analysis and Cox regression were performed according to tacrolimus levels at several time-points within 1-year posttransplantation. RESULTS: A total of 43 patients received bilateral lung transplantation. The median age was 53 years and the median follow-up was 20.5 months. Overall and 1-year patient survival rates were 55.8% and 74.4%, respectively. Infection was the most common cause of death (78.9%). Chronic lung allograft dysfunction was observed in 16.3%. A tacrolimus level <9 ng/ml at 1 month was associated with lower rejection-free survival (P = 0.009). A time-averaged tacrolimus level <10 ng/ml within 1 month posttransplantation was an independent risk factor for poor patient survival (hazard ratio: 4.904; 95% confidence interval: 1.930-12.459; P= 0.001). Furthermore, higher tacrolimus levels did not increase infectious complications. CONCLUSIONS: These finding suggest that tacrolimus levels ≥10 ng/ml within 1 month after lung transplantation appear to be associated with better patient survival.