Tacrolimus Dose and Trough Blood Levels in a US Liver Transplant Population

B. Pinsky, M. Tran, A. Riedel
HEOR, OptumInsight, Eden Prairie, MN; HEOR-US Medical and Drug Regulatory Affairs, Novartis Pharmaceuticals Corporation, East Hanover, NJ
Abstract number: D1697

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Objective

To examine tacrolimus (TAC) dose over time and by TAC trough levels in liver transplant (LTX) patients.

Methods

A retrospective analysis of transplanted liver and a prescription claim for TAC (tacrolimus) between 01Jan2004 and 31Aug2011 was conducted using a large US healthcare claims database. The date of the first TAC claim was defined as the index date. All patients were required to have continuous enrollment for 1 year prior to index date (pre-index) and a minimum of 6 months following (post-index). Evidence of LTX was defined in the pre-index period as at least one claim with a diagnosis or procedure code for LTX. Incident cases were defined as those with evidence of transplant surgery during the pre-index period; all other cases were defined as prevalent. Patients had ≥1 lab result measuring TAC trough level in the post-index period. Average TAC trough levels were examined from the index date in three month intervals through the first year. The average daily dose of TAC was also examined during the same intervals and examined in relation to trough level.

Results

Study sample included 301 incident and 156 prevalent LTX patients with a TAC trough result. Depending on time frame, 94% to 70% of patients had a TAC fill in the same time period as an available TAC lab result. Over the first year the percentage of patients with TAC levels ≥7.5 ng/ml decreased from 56% to 32%. In the prevalent group, the percentage of patients with TAC levels ≥7.5 ng/ml is 40%. Table 1 examines the shift in the population’s TAC trough levels over time as well as the relationship between dose and TAC trough level.

Conclusions

TAC dose and trough level appear to change over time as evidenced by decreasing dosage and levels. A significant number of patients remain at a TAC lever >7.5 ng/ml or higher. This suggests that TAC management is not routinely occurring.

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