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).


CONCLUSIONS
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.
Castelli-Haley
Jane
J
Teva Neuroscience, Kansas City, MO, USA.
Oleen-Burkey
Merrikay A
MA
Lage
Maureen J
MJ
Johnson
Kenneth
K
D000276:Adjuvants, Immunologic / Q000008:administration & dosage / Q000191:economics; D000328:Adult; D004334:Drug Administration Schedule; D005260:Female; D000068717:Glatiramer Acetate; D006801:Humans; D007273:Injections, Intramuscular; D007345:Insurance Claim Review; D000068556:Interferon beta-1a; D016899:Interferon-beta / Q000008:administration & dosage* / Q000191:economics; D008297:Male; D009103:Multiple Sclerosis / Q000188:drug therapy* / Q000191:economics; D015999:Multivariate Analysis; D010455:Peptides / Q000008:administration & dosage* / Q000191:economics; D012044:Regression Analysis; D012189:Retrospective Studies; D055502:Secondary Prevention; D016896:Treatment Outcome
D000276:Adjuvants, Immunologic; D010455:Peptides; D000068717:Glatiramer Acetate; D016899:Interferon-beta; D000068556:Interferon beta-1a