Intervention of Online Percent Coefficient of Variation Reporting System Reduces the Variability of Tacrolimus Trough Concentration in Kidney Transplant Recipients

Background: The online percent coefficient of variation reporting system could monitor the variation of tacrolimus trough level (T₀) and identify kidney transplant recipients (KTRs) with a higher percent coefficient of variation (%CV) instantly. Consequently, transplant doctors and pharmacists could take actions to improve drug variability. The purpose of this study was to determine the efficacy of the system for higher intrapatient variability of T₀ in KTRs. Methods: The T₀ data were collected with KTRs routinely followed up at an outpatient clinic between June 2016 and November 2016. The %CV was calculated with T₀ data within 6 months before and after the index date. The last outpatient clinic visit date was before December 1, 2016. The KTRs with %CV of T₀ greater than 22% were enrolled. Results: The study consisted of 183 KTRs (96 male, 87 female), the median age was 50 years (interquartile range [IQR], 41.0–57.0), and the median years post-kidney transplantation was 7 years (IQR, 3.0–12.4). The median T₀ and creatinine level at baseline were 6.09 ng/mL (IQR, 4.80–7.52) and 1.33 mg/dL (IQR, 1.03–1.72), respectively. After the intervention, the median %CV of T₀ was significantly lower than before, 32% (IQR, 26%–42%) vs 22% (IQR, 15%–33%), P <.001. The average improvement of %CV was also significantly better in KTRs with %CV ≥ 30% (median, from 41% to 25%) than KTRs with %CV between 22% and 30% (median, from 26% to 20%), P <.001. Conclusions: The results of this study indicate that continuously aggressive intervention with an online %CV reporting system effectively improves intrapatient variability of T₀ in KTRs.