The Effect of the 5th Sign Intervention on Medication Adherence in Kidney Transplant Recipients

The goal of this randomized controlled trial is to evaluate the effectiveness of the \"5th Sign\" intervention program-a multi-component strategy based on the Socio-Ecological Model that incorporates goal setting, action planning, medication education, problem-solving, and counseling, delivered via a custom mobile health application. The main questions it aims to answer are: * To examine the effect of the 5th Sign intervention on immunosuppressive medication adherence (measured biologically, via self-report, and mobile monitoring) in kidney transplant recipients. * To evaluate the effect of the intervention on clinical health outcomes, specifically including infection, mortality, Blood Urea Nitrogen (BUN) and creatinine levels, acute/chronic rejection, and graft loss. * To assess the effect of the intervention on the incidence of immunosuppressive drug-related side effects. Researchers will evaluate the 5th Sign intervention to see if the mobile health app and structured counseling are effective in improving medication adherence and patient outcomes. Participants will: * Be randomly assigned to either the intervention group (using the 5th Sign intervention) or the control group for a total study period of 6 months. * (If in the intervention group) Participate in active counseling and interviews for the first 3 months, followed by a 3-month monitoring period. * (If in the intervention group) Use the mobile health application continuously for 6 months for medication reminders and tracking, with their app usage evaluated on a monthly basis. * Complete questionnaires (regarding medication usage and side effects) and provide blood samples (to measure biological adherence and kidney function) twice: at the beginning of the study and at the end of the 6-month study period.