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.

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.