Clinical and economic impact of glatiramer acetate versus beta interferon therapy among patients with multiple sclerosis in a managed care population.

OBJECTIVE To examine the outcomes of use of glatiramer acetate (GA) versus beta interferons-1a (intramuscular) (1A) and -1b (1B) in patients with multiple sclerosis (MS) in a managed care setting. METHODS Data were obtained from a national retrospective claims database from January 1996 to June 2001. Patients were followed from the first prescription for immunomodulatory therapy until plan disenrollment or end of study time frame. The incidence of all relapses (defined as hospitalization for MS or ambulatory visit followed by use of systemic corticosteroids) as well as utilization and costs of MS-related care were examined for each group. Data were adjusted for variable follow-up using survival techniques. RESULTS A total of 8,457 patients receiving immunomodulatory therapy were included in the study cohort; follow-up averaged 17.3 months. Three quarters of patients were female; the mean age was 42.2 years. The risk of relapse (defined as number of new cases) at one year was significantly increased for the beta interferons relative to GA (hazard rates: 1.15 and 1.51 for 1A and 1B, respectively, P<0.01). Mean (+/- SD) costs of care also were reduced among GA patients ($9,522 [+/- $9,706] versus $9,957 [+/- $9,083] and $10,185 [+/- $9,526] for 1A and 1B, respectively). These findings persisted in multivariate analyses, controlling for differences in demographic characteristics and propensity scores for immunomodulatory therapy. CONCLUSIONS Glatiramer acetate is associated with reductions in the incidence of relapse and costs of care relative to the beta interferons among this large group of managed care patients with MS.