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

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.