Parathyroidectomy and Cinacalcet Use in Medicare-Insured Kidney Transplant Recipients

Rationale & Objective: Posttransplant hyper-parathyroidism is common, and treatment practices are poorly characterized. The goal of this study was to examine the incidence, asso-ciations, and outcomes of posttransplant para-thyroidectomy and calcimimetic use in a cohort of Medicare-insured US kidney transplant recipients. Study Design: Retrospective observational cohort study.Setting & Participants: We used the US Renal Data System to extract demographic, clinical, and prescription data from Medicare Parts A, B, and D-insured patients who received their first kidney transplant in 2007-2013. We excluded patients with pretransplant parathyroidectomy.Predictors: Calendar year of transplantation and pretransplant patient characteristics.Outcome: (1) Incidence of and secular trends in parathyroidectomy and cinacalcet use in the 3 years after transplant; (2) 90-day outcomes after posttransplant parathyroidectomy and cinacalcet initiation. Analytical Approach: Temporal trends and pre -transplant correlates of parathyroidectomy and cinacalcet use were assessed using proportional hazards models and multivariable Poisson regres-sion, respectively.Results: The inclusion criteria were met by 30,127 patients, of whom 10,707 used cinacalcet before transplant, 551 underwent posttransplant parathyroidectomy, and 5,413 filled >= 1 prescrip-tion for cinacalcet. The rate of posttransplant parathyroidectomy was stable over time. By contrast, cinacalcet use increased during the period studied. Long dialysis vintage and pre -transplant cinacalcet use were strongly associated with posttransplant parathyroidectomy and cina-calcet use. Roughly 1 in 4 patients were hospitalized within 90 days of posttransplant parathyroidectomy, with hypocalcemia-related diagnoses being the most common complication. Parathyroidectomy (vs cinacalcet initiation) was not associated with an increase in acute kidney injury.Limitations: We lacked access to laboratory data to help assess the severity of secondary/ tertiary hyperparathyroidism. The cohort was limited to Medicare beneficiaries.Conclusions: Almost one -fifth of our study cohort was treated with parathyroidectomy and/ or cinacalcet. Further studies are needed to establish the optimal treatment for posttransplant hyperparathyroidism.