Voriconazole therapeutic drug monitoring among lung transplant recipients receiving targeted therapy for invasive aspergillosis

Background Voriconazole is the first line treatment for invasive aspergillosis (IA) Current guidelines suggest performing regular voriconazole therapeutic drug monitoring (TDM) to optimize treatment efficacy. We aimed to determine if TDM was predictive of clinical outcome in LTRs. Methods Retrospective chart review was performed for all LTRs with probable or proven IA, treated with voriconazole monotherapy and who underwent TDM during therapy. Clinical outcome and toxicity were measured at 12 weeks. Classification and regression tree (CART) analysis was used to determine the most predictive voriconazole level thresholds for successful outcome. Results One hundred and eighteen TDM samples from 30 LTRs with IA were analyzed. Three LTRs were excluded due to early treatment discontinuation. The median TDM level was 1.2 mu g/ml (range 0.06-7.3). At 12 weeks, 62% (17/27) of patients had a successful outcome, while 37% (10/27) of patients failed therapy. CART analysis determined that the best predictor for successful outcome was a median TDM level >0.72 mu g/ml. Seventy percent (14/20) of patients with median TDM above 0.72 mu g/ml had a successful outcome, compared to 42.9% (3/7) of patients with a median TDM below 0.72 mu g/ml (OR 3.11; 95% CI: 0.53-20.4; P = 0.21). CART analysis determined that a TDM level greater than 2.13 mu g/ml was predictive of hepatotoxicity. Conclusions Our data suggests that a voriconazole TDM range between 0.72 mu g/ml and 2.13 mu g/ml may be associated with improved outcomes. Our study is in line with current recommendations on the use of voriconazole TDM in improving outcome and minimizing toxicity in LTR with IA.