Describing the evolution of medication nonadherence from pretransplant until 3 years post‐transplant and determining pretransplant medication nonadherence as risk factor for post‐transplant nonadherence to immunosuppressives: The Swiss Transplant Cohort Study

Summary Although medication nonadherence (MNA) is a major risk factor for poor outcomes, the evolution of MNA from pre‐ to 3 years post‐transplant among the four major organ transplant groups remains unknown. Therefore, this study described this evolution and investigated whether pretransplant MNA predicts post‐transplant immunosuppressive medication nonadherence (IMNA). Adult participants (single transplant, pretransplant and ≤1 post‐transplant assessment, using medications pretransplant) in the Swiss Transplant Cohort Study (a prospective nation‐wide cohort study) were included. Nonadherence, defined as any deviation from dosing schedule, was assessed using two self‐report questions pretransplant and at 6, 12, 24 and 36 months post‐transplant. Nonadherence patterns were modelled using generalized estimating equations. The sample included 1505 patients (average age: 52.5 years (SD: 13.1); 36.3% females; 924 renal, 274 liver, 181 lung, 126 heart). The magnitude and variability of self‐reported MNA decreased significantly from pretransplant to 6 months post‐transplant (OR = 0.21; 95% CI: 0.16–0.27). Post‐transplant IMNA increased continuously from 6 months to 3 years post‐transplant (OR = 2.75; 95% CI: 1.97–3.85). Pretransplant MNA was associated with threefold higher odds of post‐transplant IMNA (OR = 3.10; 95% CI: 2.29–4.21). As pretransplant MNA predicted post‐transplant IMNA and a continuous increase in post‐transplant IMNA was observed, early adherence‐supporting interventions are indispensible.