Dialysis Nonadherence and Kidney Transplant Outcomes: A Retrospective Cohort Study

Rationale and Objective Concerns about non-adherent behaviors often prevent dialysis patients from entering waitlists for transplantation, despite an inconsistent association with posttransplant outcomes. We examined the association between plausible metrics of non-adherence related to dialysis treatment and posttransplant outcomes. Study Design Retrospective cohort. We linked national dialysis treatment data with transplant registry data. Setting and Participants Adult patients on maintenance hemodialysis from 1/1/2004-12/31/2014 who received a kidney transplant at US centers. Exposures We examined five nonadherence metrics: serum potassium (≥5.2 mEq/L), serum phosphorus (>5.5 mg/dL), intradialytic weight gain (IDWG, ≥5 L), shortened treatments (≥30 minutes) and missed treatments (≥1); missed treatment data was only available for 2004-2009. These metrics were characterized as the proportion of time under observation. Dialysis observation time was divided into 3-month intervals (quarters) and the number of “non-adherent” measurements in each domain was calculated for each quarter. Outcomes Allograft loss; mortality; and acute rejection in the first posttransplant year. Analytical approach Using Cox proportional hazards and logistic regression, we estimated the hazard ratios (HRs) for graft loss and mortality, and odds ratios (OR) for rejection. Results 9543 patients met inclusion criteria. In our primary model, hyperphosphatemia (aHR 1.27, 05% CI 1.08-1.49), IDWG (aHR 1.39, 95% CI 1.23-1.59) and shortened treatments (aHR 1.54, 95% CI 1.12-2.13) were associated with greater rates of allograft loss but hyperkalemia was not. IDWG (aHR 1.49, 95% CI 1.29-1.73) and shortened treatments (aHR 1.34, 95% CI 1.13-1.58) were associated with mortality while hyperkalemia and hyperphosphatemia were not. Only shortened treatments was associated with an increased risk of acute rejection (aOR 3.88, 95% CI 1.98-7.58). In models limited to the years 2004 to 2009 that included missed treatments, missed treatments were only associated with mortality. Limitations Unmeasured confounding (e.g., dietary data); adherence metrics used may have multiple, complex causes. Conclusions Plausible measures of dialysis nonadherence have long-term associations with allograft and patient survival. Behavioral metrics were more closely associated with outcomes than laboratory markers. The implications of non-adherent behaviors for dialysis patients must be carefully considered before excluding patients from transplantation.