Evaluation of medication adherence over a decade following kidney transplantation: integration of biological and self-reported data

Background This study aims to determine the course of immunosuppressive medication adherence (MA) in individuals who have undergone kidney transplantation for over a decade and to identify the demographic and clinical factors affecting this adherence. Methods This retrospective and cross-sectional descriptive study evaluated the biological adherence of 103 kidney transplant recipients (KTRs) at 12 different time points using tacrolimus and cyclosporine blood levels. Self-reported adherence was assessed via The Immunosuppressant Therapy Adherence Scale. Associations between adherence and demographic and clinical variables were also analyzed. Results The mean time since transplantation was 11.77 ± 1.46 years. Biologically, 43.3% of patients had low MA. In contrast, self-reported adherence was 82.52%. No statistically significant correlation was found between biological and self-reported adherence outcomes. Patients with low biological adherence presented increased blood urea nitrogen (BUN) levels at 6 months and 9 years post-transplant. Similarly, patients with low self-reported adherence had increased BUN levels at 10 years. Self-reported adherence scores were significantly lower among patients with a history of graft rejection ( p < 0.001). No significant associations were found between MA and variables such as sex, donor type, or age ( p > 0.05). Conclusions This study identifies significant discrepancies between biological and self-reported methods for evaluating long-term adherence to immunosuppressive therapy. The results indicate that adherence fluctuates over time, highlighting the need for multidimensional assessment strategies. The implementation of standardized, and complementary tools is crucial to improving graft and patient survival. Future multicenter research should investigate pre-transplant predictors to optimize long-term medication adherence.