Immunosuppressant therapeutic drug monitoring and trough level stabilisation after paediatric liver or kidney transplantation.

BACKGROUND: Immunosuppressive therapy must be guided by therapeutic drug monitoring (TDM) in paediatric liver (LT) and kidney transplantation (KT) patients to prevent under- and overdosing, which have clinical consequences. AIM: The purpose of our study was to analyse TDM results in our institutions and evaluate factors associated with blood level stabilisation after LT and KT. METHODS: Blood levels of immunosuppressants were measured by immunoassay analysis. We compared blood level stabilisation between LT and KT, and evaluated associated factors in a retrospective study in two Swiss university hospitals. RESULTS: Forty-six patients (27 LT [median age 1.0 y], 19 KT [15.1 y]) were included. During the first month after transplantation, 32.8% (LT) and 41.2% (KT) of tacrolimus, and 22.1% (KT) of ciclosporin trough levels (measured before the next dose) were within target. In KT, trough levels stabilised earlier for tacrolimus than for ciclosporin (p = 0.02). Intensive care and hospital discharge occurred earlier in KT patients (p < 0.001). Living-donor LT was associated with an earlier intensive care discharge compared with deceased donor (5.5 vs 11 days, p = 0.02). Primary metabolic disease and graft/recipient weight-ratio >= 0.03 was associated with earlier tacrolimus level stabilisation (14 vs 18 days, p = 0.01 and 15 vs 22 days, p = 0.05, respectively). In KT, recipient age (>= 15.1 years) and weight (>= 39.4 kg) were associated with an earlier trough level stbilisation (both 13 days vs not reached, p < 0.001), and age with earlier hospital discharge (10 vs 14 days, p = 0.02). CONCLUSION: Immunosuppressant trough levels were often outside the target range in the first month after LT and KT. Organ-specific factors were associated with trough stabilisation.