Utilization and costs of medications associated with CKD mineral and bone disorder in dialysis patients enrolled in Medicare Part D

Abstract

Background: Information is limited regarding utilization patterns and costs for chronic kidney disease-mineral and bone disorder (CKD-MBD) medications in Medicare Part D-enrolled dialysis patients.

Study design: Retrospective cohort study.

Setting & participants: Annual cohorts of dialysis patients, 2007-2010.

Predictors: Cohort year, low-income subsidy status, and dialysis provider.

Outcomes: Utilization and costs of prescription phosphate binders, oral and intravenous vitamin D analogues, and cinacalcet.

Measurements: Using logistic regression, we calculated adjusted odds of medication use for low-income subsidy versus non-low-income subsidy patients and for patients from various dialysis organizations, and we report per-member-per-month and average out-of-pocket costs.

Results: Phosphate binders (∼83%) and intravenous vitamin D (77.5%-79.3%) were the most commonly used CKD-MBD medications in 2007 through 2010. The adjusted odds of prescription phosphate-binder, intravenous vitamin D, and cinacalcet use were significantly higher for low-income subsidy than for non-low-income subsidy patients. Total Part D versus CKD-MBD Part D medication costs increased 22% versus 36% from 2007 to 2010. For Part D-enrolled dialysis patients, CKD-MBD medications represented ∼50% of overall net Part D costs in 2010.

Limitations: Inability to describe utilization and costs of calcium carbonate, an over-the-counter agent not covered under Medicare Part D; inability to reliably identify prescriptions filled through a non-Part D reimbursement or payment mechanism; findings may not apply to dialysis patients without Medicare Part D benefits or with Medicare Advantage plans, or to pediatric dialysis patients; could identify only prescription drugs dispensed in the outpatient setting; inability to adjust for MBD laboratory values.

Conclusions: Part D net costs for CKD-MBD medications increased at a faster rate than costs for all Part D medications in dialysis patients despite relatively stable use within medication classes. In a bundled environment, there may be incentives to shift to generic phosphate binders and reduce cinacalcet use.

Keywords: Chronic kidney disease (CKD); Medicare Part D; calcimimetics; dialysis; medication costs; mineral and bone disorder; phosphate binders; vitamin D analogues.