Background: Nonadherence with immunosuppressive therapy after renal transplantation is a major clinical concern, but longitudinal data are sparse. Adherence data were recorded during the Mycophenolic Acid Observational REnal Transplant (MORE) study to help inform compliance management decisions.
Material and methods: Prospective data were analyzed from the four-year, observational MORE study of de novo adult renal transplant recipients receiving mycophenolic acid (MPA) as enteric-coated mycophenolate sodium (EC-MPS) or mycophenolate mofetil (MMF) at 40 US sites under routine management. Adherence was assessed using the Immunosuppressant Therapy Adherence Scale (ITAS): total score 0-12 (12, adherence; <12, nonadherence). A logistic regression model was used to identify factors associated with nonadherence.
Results: In total, 808/946 recipients (85.4%) provided ≥1 ITAS score. Nonadherence was reported by 24.8%, 31.5%, 33.0%, 39.8%, 35.4% and 26.4% at months 3, 6, 12, 24, 36 and 48, respectively. Mean ITAS score was higher with EC-MPS vs. MMF at months 24 (11.3[1.0] vs. 10.9[1.4], p=0.001) and 36 (11.4[1.0] vs. 11.1[11.3], p=0.024). The odds ratio for nonadherence was 1.60 (95% CI 1.17, 2.19; p=0.003) for African Americans vs. non-African Americans. The rate of biopsy-proven acute rejection was 12.7% (51/401) in nonadherent recipients vs. 11.3% (46/406) in adherent recipients (p=0.59); graft loss was 4.7% (19/402) vs. 3.0% (12/406) (p=0.20); death was 1.5% (6/402) vs. 4.7% (19/406) (p=0.013).
Conclusions: Adherence to the immunosuppressive regimen decreases over time, highlighting the need to monitor and encourage adherence even in long-term maintenance kidney transplant patients. Other than African American race, demographic factors may be of limited value in predicting nonadherence.