OBJECTIVE: Medication nonadherence (MNA) plays a key role in transplant (Tx) survival in pediatric kidney patients (pts). However, identification of MNA is challenging and tools to predict pts at risk for MNA are inexact. While several tools have been suggested to identify pts at high risk for MNA, few studies have examined such tools prospectively to identify pts at risk for adverse immunological outcomes of MNA.

METHOD: The IMPACT study evaluated the 1 year natural history of a low-risk, unselected longitudinal cohort of 106 pediatric kidney Tx pts on tacrolimus (TAC) maintenance immunosuppression. Protocol biopsies were obtained at 6 and 12 months. Self-report MNA was assessed by Brief Medication Questionnaire (BMQ), while barriers to adherence were measured by the Parent Medication Barrier Scale (PMBS) and Adolescent Medication Barrier Scale (AMBS). We compared these measures with a direct measurement of TAC ingestion, the % coefficient of variation (CV%) of TAC trough levels assessed over the first year post Tx. We examined the relationship between these measures of MNA and immunological outcomes including biopsy proven acute rejection (BPAR) and de novo (dn) donor specific antibodies (DSA).

RESULTS: PMBS, AMBS, and BMQ obtained in the first post-Tx month did not predict subsequent BPAR or dn DSA (p =0.95, 0.44, 0.15 respectively). However, pts with a PMBS score of ≥ 2 elements at 12 months had a higher risk of a combination of either BPAR and/or dn DSA (60%), compared to pts with < 2 PMBS elements (35%) (p < 0.001). Moreover, we found that patients with a TAC CV > 41% at 12 months had a higher rate of BPAR (38%) in the first year compared to patients with CV <41% (14%) (p = 0.04). There was no correlation between TAC CV% and self-reported BMQ or any of the barrier analyses.

CONCLUSION: In pediatric kidney Tx pts, self-assessment measures are poor predictors of BPAR or dn DSA. Yet, parental insight using PMBS at 1 year may be predictive of poor immunological outcomes. TAC CV% with a value of >41% is a more useful indicator of potential BPAR and can be utilized on an ongoing basis to determine high-risk of BPAR.

CITATION INFORMATION: Dokras A., Pearl M., Peipert J., Grimm P., Warshaw B., Chambers E., Kirk A., Ettenger R. Assessment and Outcomes of Medication Nonadherence in Pediatric Kidney Transplant Recipients: Results from the IMPACT Study Am J Transplant. 2017;17 (suppl 3).

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