International Variability of Barriers to Adherence to Immunosuppressive Medication in Adult Heart Transplant Recipients. A Secondary Data Analysis of the BRIGHT Study.

Non-adherence to immunosuppressive medication among transplant patients is associated with poor clinical outcomes and higher economic costs. Barriers to immunosuppressives are a proximal determinant of non-adherence. So far, international variability of barriers to adherence in transplantation has not been studied. As part of the cross-sectional multi-country and multi-center BRIGHT study, barriers to adherence were measured in 1,382 adult heart transplant recipients of 11 countries using the 28-item self-report questionnaire "Identifying Medication Adherence Barriers" (IMAB). Barriers were ranked by their frequency of occurrence for the total sample and by country. Countries were also ranked the by recipients' total number of barriers. Intra-class correlations were calculated at country and center level. The five most frequently mentioned barriers were sleepiness (27.1%), being away from home (25.2%), forgetfulness (24.5%), interruptions to daily routine (23.6%) and being busy (22.8%), fairly consistently across countries. The participants reported on average three barriers, ranging from zero up to 22 barriers. The majority of the variability among reported barriers frequency was situated at the recipient level (94.8%). We found limited international variability in primarily person-level barriers in our study. Understanding of barriers in variable contexts guides intervention development to support adherence to the immunosuppressive regimen in real-world settings.