AUTHOR=Russell Lippincott Cynthia L. , Pironet Antoine , Sarigol Ordin Yaprak , Bartlett Ellis Rebecca , Celik Buket , Ayten Kankaya Eda , Stephens Mary Beth , Yildiz Serkan , Yerram Preethi , Awopetu Wuraola , Wakefield Mark , Henderson Elizabeth TITLE=The SystemCHANGE™ intervention improves immunosuppressive medication-taking habit: a secondary analysis of the MAGIC studies JOURNAL=Transplant International VOLUME=Volume 39 - 2026 YEAR=2026 URL=https://www.frontierspartnerships.org/journals/transplant-international/articles/10.3389/ti.2026.16252 DOI=10.3389/ti.2026.16252 ISSN=1432-2277 ABSTRACT=Habit impacts healthy behaviors. The SystemCHANGE™ intervention supports associating medication taking with existing habits or creating new habits to improve medication adherence. This secondary analysis of United States and Türkiye MAGIC study data examines differences in habit between SystemCHANGE™ and attention control groups, differences in habit between countries, and habit as a relationship mediator between the SystemCHANGE™ intervention and immunosuppressive medication adherence in adult kidney transplant recipients. The Medication Event Monitoring System measured medication adherence. Objective habit index was computed during screening, intervention, and maintenance. During the SystemCHANGE™ intervention, habit strength was higher than during the screening and maintenance periods in both groups (mean difference 0.042, 95% confidence interval (CI): 0.004 to 0.080, p = 0.030). Habit index was lower for US participants compared to Turkish participants (mean difference −0.195, 95% CI: −0.300 to −0.089, p < 0.001). Habit was a mediator of the SystemCHANGE™ intervention on medication adherence (indirect effect was 0.094, 95% CI: 0.080 to 0.114, p < 0.001). The SystemCHANGE™ intervention exerted an impact on habit in two different populations which then had a positive impact on medication adherence.