Introduction: In our previous prospective single-center study, using validated self-administered instruments, we demonstrated correlation between depression and nonadherence in recipients of kidney transplants. The purpose of this study was to confirm our finding that depression was associated with nonadherence in a large database of transplant recipients for which we used the United States Renal Data System (USRDS).
Methods: We conducted a retrospective cohort study of 32,757 Medicare primary renal transplant recipients in the USRDS who underwent transplantation from January 1, 2000 to July 31, 2004 and were followed up through December 31, 2004, assessing Medicare claims showing depression and nonadherence based on codes of the International Classification of Diseases, 9th Revision.
Results: Logistic regression analysis (adjusted hazards ratio 1.69 with 95% confidence interval, 1.48-1.92) and log rank test (P < .0005) showed that there was a strong association of depression and nonadherence. Depression was associated with nonadherence, irrespective of the time of depression, whether it was pretransplantation (P < .001) or posttransplantation (P < .001). Nonadherence was also associated with black race (P < .001), younger age (P < .001), less HLA mismatch (P < .005), recipients of living kidneys and patients who underwent transplantation a longer time ago (P < .001). Furthermore, patients with 12 or less years of education were more nonadherent (P < .001). Among the transplant donor factors we investigated, donor black race (P < .001) and expanded criteria donor kidneys were strongly associated with nonadherence (P < .001). However, donor age and delayed graft function were not significantly associated with nonadherence.
Conclusions: Future clinical trials of immunosuppressive therapy should assess the impact of depression on graft survival.