The use of disease-modifying agents among multiple sclerosis patients enrolled in medicare from 1995 to 2002 and the impact of medicare part D: Analysis of claims data from the medicare current beneficiary survey

The goals of this analysis were as follows:(1) identify the prevalence of access barriers to disease-modifying agents (DMAs) used in the United States for the treatment of multiple sclerosis (MS), (2) identify the relationship between patient characteristics and use of DMAs, and (3) interpret the results in the context of Medicare Part D. Using claims data from the Medicare Current Beneficiary Survey (MCBS) 1992 to 2001, we identified beneficiaries with a diagnosis of MS on ⩾4 claims. To adapt for the bimodality of the claims distribution and to capture the majority of MS claims, ⩾4 claims were used. We estimated the mean out-of-pocket price of prescription medications and prevalence of perceived economic barriers to address the hypothesis that the expansion of Medicare to include an out-patient drug benefit will decrease beneficiaries' burden of MS. A total of 416 patients with MS were identified with the MCBS claims data. Furthermore, data for 3 DMAs used to manage MS were available: interferon β-1b, interferon β-1a, and glatiramer acetate. Data were available for interferon β-1b for the years 1995 to 2002, and for interferon β-1a and glatiramer acetate for the years 1999 to 2002. The mean out-of-pocket price per prescribing event (typically 30 days) for interferon β-1b was US $44.40 from 1995 to 1998 and US $15.08 from 1999 to 2002. Between 1999 and 2002, the mean out-of-pocket price per prescribing event for interferon β-1a was US $84.74; for glatiramer acetate during the same period, it was US $114.90. Assuming complete compliance for the year, the mean out-of-pocket burden per patient for each medication using the 1999-to-2002 numbers would be US $1016.88 for interferon β-1a, US $548.91 for interferon β-1b, and US $1378.80 for glatiramer acetate. The annual prevalence of use of any DMA increased from 6.5% during the years 1995 to 1998 to 21.2% during the years 1999 to 2002. Our findings suggest that these MSpatients, who were Medicare beneficiaries, faced considerable economic barriers to necessary health care, particularly prescription medications. Substantial differences existed in the out-of-pocket prices of DMAs between the 2 time periods analyzed. These differences could be expected to be attenuated by the expansion of Medicare to include a drug benefit (Part D), which will increase insurance coverage for DMAs and reduce the out-of-pocket burden of MS therapies.