Parathyroidectomy and Cinacalcet Use in Medicare-Insured Kidney Transplant Recipients

Abstract

Rationale & objective: Posttransplant hyperparathyroidism is common, and treatment practices are poorly characterized. The goal of this study was to examine the incidence, associations, and outcomes of posttransplant parathyroidectomy 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 pretransplant correlates of parathyroidectomy and cinacalcet use were assessed using proportional hazards models and multivariable Poisson regression, 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 prescription for cinacalcet. The rate of posttransplant parathyroidectomy was stable over time. By contrast, cinacalcet use increased during the period studied. Long dialysis vintage and pretransplant cinacalcet use were strongly associated with posttransplant parathyroidectomy and cinacalcet 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.

Keywords: Acute renal failure; ICD-9-CM codes; United States Renal Data System (USRDS); calcium; clinical nephrology; cohort study; hospitalization; hyperparathyroidism; kidney transplantation; mineral metabolism; outcomes; parathyroid hormone.