Prediction of Nonadherence and Renal Prognosis by Pre-Transplantation Serum Phosphate Levels

BACKGROUND: Identifying characteristics of patients at high risk of poor adherence before transplantation would be advantageous. However, the optimal approach for characterizing such patients remains unknown. We aimed to evaluate the association between factors for hemodialysis nonadherence and post-transplant renal prognosis. We hypothesized that these factors would influence post-transplantation adherence and worsen renal prognosis. MATERIAL/METHODS: We reviewed patients on hemodialysis who underwent kidney transplantation at our hospital between 2000 and 2017 to identify risk factors associated with poor prognosis. The patients’ background and pre-transplantation data, known hemodialysis nonadherence factors, serum phosphate and potassium levels, and interdialytic weight gains were evaluated. The primary endpoint was renal death. We also evaluated the fluctuation of calcineurin inhibitor concentration and weight gain after transplantation. RESULTS: Seventy-seven patients were eligible, and the mean observational period was 83.2 months (standard deviation, 50.5). Thirteen patients reached the endpoint. Cox proportional hazards regression analysis showed that pre-transplantation serum phosphate level was a risk factor for renal death (p<0.05), while serum potassium levels and weight gain were not. In addition, fluctuation of calcineurin inhibitor concentration was observed in patients with higher phosphate levels before transplantation (p=0.03). Weight gain after transplantation was not associated with the hemodialysis nonadherence factors. CONCLUSIONS: High pre-transplantation serum phosphate levels are considered to represent poor drug adherence and/or an unhealthy lifestyle. Patient education that conveys the importance of adhering to medications and provides nutritional guidance is crucial for improving post-transplantation renal prognosis.