Glatiramer acetate and interferon beta-1a for intramuscular administration: a study of outcomes among multiple sclerosis intent-to-treat and persistent-use cohorts.

OBJECTIVE: To study outcomes of multiple sclerosis (MS) patients treated with either glatiramer acetate (Copaxone) or interferon beta-1a for once-weekly, intramuscular administration (Avonex). METHODS: An 'intent-to-treat' (ITT) cohort (n=1282) was established, consisting of patients diagnosed with MS who began therapy on either glatiramer acetate (GA) or intramuscular interferon beta-1a (IFN beta-1a-IM) and had continuous insurance coverage from 6 months before to 24 months after the date when they began taking the medication. A 'persistent use' (PU) cohort (n=639) was also constructed, consisting of individuals who, in addition to the criteria listed above, had a claim for GA or IFN beta-1a-IM within 28 days of the end of the 2-year post-period. Data were obtained from the i3 InVision Data Mart Database from July 2001 to June 2006. Multivariate regressions were used to examine both the 2-year total direct medical costs and the likelihood of relapse associated with the use of each of these alternative MS medications. A relapse was defined as either being hospitalized with a principal diagnosis of MS or having an outpatient visit with a MS diagnosis followed within 7 days by a claim for a corticosteroid. All regressions controlled a wide range of factors that may potentially affect outcomes. RESULTS: In the ITT cohort, patients who started therapy on GA had a significantly lower 2-year risk of relapse (10.01 vs. 5.18%; p=0.0034) as well as significantly lower 2-year total medical costs ($44,201 vs. $41,121; p=0.0294). In the PU cohort, patients who used GA also had a significantly lower 2-year risk of relapse (7.25 vs. 2.16%; p=0.0048) as well as significantly lower total medical costs ($67,744 vs. 63,714; p=0.0445). LIMITATIONS: The analyses relies on an administrative claims database of an insured population and hence, may not be generalizeable to other populations. In addition, such a database precludes measurement of lost work time, unemployment, caregiver burden or other costs associated with MS. CONCLUSIONS: Results from this study indicate that the use of GA is associated with significantly lower probability of relapse as well as significantly lower 2-year total direct medical costs than IFN beta-1a-IM.

Glatiramer acetate and interferon beta-1b: a study of outcomes among patients with multiple sclerosis.

INTRODUCTION: To study the medical cost and probability of relapse in patients with multiple sclerosis (MS) treated with either glatiramer acetate (GA) or interferon beta-1b (IFN beta.1b). METHODS: Data were obtained from the i3 InVision Data Mart Database from July 2001 to June 2006. We established an "intent-totreat" (ITT) cohort (n=842) of patients diagnosed with MS who began treatment with either GA or IFN beta-1b and had continuous insurance coverage from 6 months before to 2 years after the date when they began taking the medication. We also created a "continuous use" (CU) cohort (n=418) of individuals who, in addition to the criteria listed above, used either GA or IFN beta-1b within 28 days of the end of the 2-year postperiod. Using multivariate regressions, we examined both the 2-year total average direct medical costs and the likelihood of relapse within this period associated with the use of each of these MS medications. We defined relapse as being either hospitalization with a principal diagnosis of MS or having an outpatient visit with a diagnosis of MS and then prescribed steroids within a 7-day period. All regression analyses controlled for a wide range of factors that may potentially affect outcomes. RESULTS: In the ITT cohort, patients who started treatment with GA had a significantly lower 2-year estimated risk of relapse (13.54% vs. 5.31%; P=0.0006). In the CU cohort, patients who used GA also had a significantly lower 2-year estimated risk of relapse (10.91% vs. 2.09%; P=0.0018), as well as significantly lower average total medical costs ($53,157 vs. $48,130; P=0.0345). CONCLUSIONS: Results from this study indicate that users of GA have a significantly lower probability of 2-year relapse than users of IFN beta-1b. In addition, among continuous users, the 2-year total average direct medical costs are significantly lower for users of GA than for users of IFN beta-1b.