Is Non-Adherence a Contributing Factor to Kidney Transplantation Failure?

Research Objective. The association between post-transplant non-adherence in immunosuppressive medications and kidney transplantation failure has been explored in the end-stage renal disease transplantation literature. Population-based information has not yet been formed due to limited data sources. I am interested in using a different non-adherence measure to revisit this important research question by using a broader data set and a more robust statistical approach. Study Design. Noncompliance was measured as the total number of hemodialysis (HD) sessions skipped during the study period between 2004 and 2006. The dependent variable is a binary variable coded “1” if a kidney transplantation failure occurred and “0” if the transplantation was successful. I used three Cox proportional hazards models to examine the effect of non-adherence on the risk of having a kidney transplantation failure, after adjusting for none, some, and a full list of patient characteristics and comorbidities. Population Studied. I used Standard Analytical Files (SAF) from the Centers for Medicare and Medicaid Services (CMS) to identify patient information with respect to kidney transplantation and transplantation failure. The final study sample included 18,393 kidney transplantation recipients. Patient demographics, time since start of renal replacement therapy, functional status, comorbidities, and interrupted dialysis months were obtained from the CMS Medical Evidence Form (CMS Form 2728) and/or Medicare claims. Principal Findings. About 16 percent of the kidney transplant recipients experienced a kidney transplantation failure, with an average duration of 237 days. The total number of HD sessions skipped was 2.2 days (SD=6.5 days). These kidney transplant recipients had a higher ratio of being on dialysis treatments for more than three years compared to all HD patients (61 percent to 49 percent). Model 1, the unadjusted model, showed that the total number of HD sessions skipped was associated with a 0.3 percentage increase in kidney transplantation failure. Model 2 and Model 3 produced similar results. Conclusions. Despite the fact that each model used a different set of covariates, the hazards ratio on non-adherence remained unchanged and statistically insignificant, suggesting that the finding of no association between non-adherence and kidney transplantation failure is a strong and consistent result. Implications for Policy, Delivery or Practice. Previous studies consistently found an association between non-adherence in medication regime and kidney transplantation failure, and emphasized the importance to design schemes to improve patients’ adherence in medication. In contrast to previous studies, this study found that there is no association between non-adherence in HD sessions and kidney transplantation failure. From a policy perspective, this finding is encouraging. Increasing medical costs arising from a failed organ is not associated with pre-transplant non-adherence. When evaluating the Kidney Allocation Score system, non-adherence in HD sessions probably needs not to be included in the calculation. Findings also suggest that implementing an intervention to improve non-adherence in HD sessions in order to decrease the likelihood of kidney transplantation failure perhaps will not be cost-effective. Finally, these findings do not provide an incentive for HD patients to improve pre-transplant adherence.