Defense Date

2012

Document Type

Dissertation

Degree Name

Doctor of Philosophy

Department

Pharmaceutical Sciences

First Advisor

Norman V. Carroll

Abstract

Oral cancer drugs are branded and expensive medications that generally do not have generics available. The restrictions of the Medicare Part D program, including the coverage gap and high cost-sharing, and the high cost of oral chemotherapy may lead to patients’ non-adherence to medication. Few studies have examined the cost and utilization of oral anti-cancer medications. This study will be the first to examine the costs associated with the use of oral anti-cancer medications and the impact of cost-sharing and type of prescription drug subsidy on medication discontinuation in the Medicare Part D elderly population. Objectives: To determine the usage and costs of oral cancer treatment in elderly Medicare Part D beneficiaries and to examine the relationship between out of pocket costs and medication discontinuation or delay. Methods: A cross-sectional study of the spending and usage of oral cancer drugs in the Medicare Part D population was conducted. A 5% random sample of 2008 Medicare beneficiaries was used. The study sample included all members of this group who: 1) were 65 years of age and older and 2) filled at least one prescription for imatinib, erlotinib, anastrozole, letrozole, or thalidomide. We examined the average costs patients paid per day, the cost that the Part D plan paid per day, and the total cost that patients paid for the entire year for each drug. The demographic characteristics and type of prescription drug subsidy of Part D beneficiaries who used oral cancer drugs were reported in frequency counts and percentages. We also determined the percentage of enrollees who entered the Part D coverage gap, the time and duration that they fell into the coverage gap, the number of beneficiaries who discontinued treatment and the association between OOP costs and medication discontinuation or delay, controlling for polypharmacy, prescription coverage and socio-demographic factors. Results: Prescription drug subsidy was categorized in four groups: 1) Dual Eligible (DE), 2) full Low Income Subsidy (LIS), 3) partial LIS, and 4) no subsidy. Mean out-of-pocket (OOP) costs per day were between $0.03 and $0.09 for DE beneficiaries, between $0.04 and $0.23 for full LIS beneficiaries, between $1.17 and $6.34 for partial LIS beneficiaries and between $2.93 and $36.84 for beneficiaries who did not receive a subsidy. On average, the beneficiaries who used oral cancer medications were between 75 and 76 years of age. Over half of oral cancer medication users were Caucasian and female. Over two-thirds of oral cancer medication users received no subsidies for their prescription coverage. About 99% of users of the more expensive drugs - imatinib, erlotinib and thalidomide - entered the coverage gap and the majority of these entered the coverage gap at the time of their first fill. In contrast, beneficiaries who filled the less expensive drugs - anastrozole and letrozole - entered the coverage gap later. Less than 7% entered the coverage gap at the time of the first fill of their prescriptions. Beneficiaries who used imatinib, erlotinib, or thalidomide spent approximately a month in the coverage gap. Over the course of a year, the majority of their time was spent in the catastrophic phase. Approximately 33-60% of total oral cancer drug users discontinued their therapies. About 50% of these discontinued during the coverage gap for anastrozole and letrozole and about 80% discontinued during the catastrophic phase for imatinib, erloinib and thalidomide. OOP costs were associated with medication discontinuation for all five oral cancer drugs. The odds of discontinuation and delay increased 101%, 170%, and 264% for each $100 increase in OOP spending for imatinib, erlotinib and thalidomide users, respectively. The odds of discontinuation and delay increased 9%-10%, and 6-8% for every $10 increase in OOP spending for anastrozole and letrozole users, respectively. Conclusions: About 33-60% of all users discontinued their therapies. Beneficiaries receiving subsidies had low OOP costs, averaging between $0.03 and $6.34 per day. Beneficiaries on the more expensive drugs and not having subsidies had high OOP costs, averaging between $15.66 and 36.84 per day. Higher OOP costs were associated with an increased likelihood of discontinuation or delay.

Rights

© The Author

Is Part Of

VCU University Archives

Is Part Of

VCU Theses and Dissertations

Date of Submission

May 2013

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