Self-reported Non-adherence to Immunosuppressive Medication Detected by the BAASIS Predicts Allograft Rejections in Kidney Transplant Recipients.

Background: After kidney transplantation adherence to immunosuppressive medication is crucial for graft survival and its assessment requires valid measurements. The Basel-Assessment-of-Adherence-to-Immunosuppressive-Medications-Scale (BAASIS) is a validated self-report tool to detect non-adherence, however its ability to predict clinically relevant outcomes remains to be established.

Methods: In this prospective cohort study including 226 consecutive kidney graft recipients transplanted at the Medical University of Vienna between 2018 and 2019 the adherence towards immunosuppressive medication was monitored for 2 years after transplantation. The BAASIS was applied at the first outpatient visit and at months 3, 6, 9, 12, and 24 post-transplant to assess the implementation and persistence phase of adherence. Non-adherence was defined by any positive response to one of the BAASIS-items. The primary endpoint was biopsy-proven allograft rejection defined by the BANFF meeting report during a maximum follow-up of 4 years.

Results: Of the total study cohort (median age 56 years [IQR 46-63], 75 [33%] female), 125 recipients (55%) reported non-adherence at least once. Self-reported non-adherence increased within the first three months from 11% to 31% and remained between 27% and 32% at month 6 to 24 post-transplant. Non-adherent recipients experienced more allograft rejections than adherent patients (24%, n=30 vs. 7%, n = 7; P < 0.001) during a median follow-up of 3.7 years (IQR 1.0-4.0). Using a time-dependent Cox regression model, the adjusted hazard ratio for allograft rejection associated with previously reported non-adherence was 2.90 (95% CI 1.51-5.58; P = 0.001) accounting for recipient sex, age at transplantation and history of previous transplantation.

Conclusion: Our findings support the clinical value of the BAASIS. Its implementation into routine post-transplant care may facilitate the identification of clinically relevant medication non-adherence, enabling timely interventions.