INTRODUCITON AND OBJECTIVE: Kidney transplant longevity is largely related to immunosuppressive efficacy, which is highly dependent on patient adherence. Drug dosing frequency is one way the prescriber can influence adherence. The objective of this study is to determine if conversion from twice to once daily tacrolimus improves medication adherence in kidney transplant recipients.

METHODS: This is a retrospective cohort study examining kidney transplant recipients at our institution transplanted between 2005-2014 who were prescribed twice daily tacrolimus and subsequently converted to once daily formulations. The primary outcome is the rate of adherence to tacrolimus. Adherence was assessed by review of pharmacy prescription fill data and calculation of the cumulative days lapsed between refills, expressed as the percentage medication missed days (PMD): a positive value indicated days lapsed between refills while a negative value indicated refills picked up prior to the end of the previous prescription duration indicating adequate supply of medication. Patients were subdivided into tertiles of PMD on twice daily dosing and compared to post-conversion PMD within tertiles. Statistical analysis included two-tailed paired t-test for comparison of adherence rates, and Chi-square analysis of the distribution of donor types, with an alpha of 0.05.

RESULTS: A total of 203 patients met inclusion criteria for analysis. The mean age was 46.5 (SD 15.1) years (2-80 years). The average PMD while on twice daily dosing was -5.3% and while on daily dosing was -9.2% (p=0.13). When patients were subsequently divided into tertiles based on their PMD on twice daily tacrolimus, the first tertile showed worsening of adherence after conversion from twice daily to daily dosing (-30.2% to -10.6%, p <0.001) but clinically remained “adherent”. The second tertile did not significantly change after conversion to (-5 to -10%, p = 0.07). The third tertile showed significant improvement in adherence, both statistically and clinically, after conversion to daily dosing (+23% to -7%, p < 0.001).

CONCLUSIONS: The conversion to once daily tacrolimus has the potential to significantly improve adherence in a subset of the kidney transplant population. Those with the worst adherence (3rd tertile of PMD) show the greatest improvement with a reduced frequency of medications while those with good baseline adherence on twice daily dosing remain adherent after conversion.

CITATION INFORMATION: Levine M, Wen K. Conversion from Twice Daily to Once Daily Tacrolimus Improves Adherence in Kidney Transplant Recipients. Am J Transplant. 2017;17 (suppl 3).

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