COPENHAGEN—Among patients with multiple sclerosis (MS) in the United States, the rate of relapses was substantially lower in patients who switched from interferon therapy to fingolimod, compared with those who switched to glatiramer acetate, according to a retrospective US claims database analysis presented at the 29th Congress of the European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS).
Niklas Bergvall, PhD, from Novartis Pharma, Basel, Switzerland, and colleagues used US administrative claims data from the IMS PharMetrics Plus Database to compare relapse rates among patients with MS who switched from interferon to fingolimod or glatiramer acetate between October 1, 2010, and September 30, 2011. According to the researchers’ retrospective analysis study protocol, patients needed to switch within 90 days of discontinuing interferon therapy. In addition, patients must have had a diagnosis code for MS within 360 days of the switch (ie, the total period during which the patients were followed).
The occurrence of any type of relapse (identified using a claims-based algorithm) while persistent to fingolimod or glatiramer acetate (period prior to a gap of more than 60 days or switch to another disease-modifying therapy) was measured over 360 days following the switch. The probability of having one or more relapses was estimated using a multivariate logistic regression model, and differences in the rate of relapses were assessed using a multivariate generalized linear model with a negative binomial distribution.
The total sample included 408 patients—198 patients who switched to fingolimod and 210 patients who switched to glatiramer acetate. Before switching, 32.3% and 49.0% of patients had one or more relapses in the fingolimod and glatiramer acetate cohorts, respectively.
In unadjusted analyses, the proportion of patients with one or more relapses during the persistence period was lower for patients treated with fingolimod (16.7%) than for those treated with glatiramer acetate (29.5%) despite a longer mean persistence period (307 vs 282 days for the fingolimod and glatiramer acetate cohorts, respectively). In the persistence period, annualized relapse rates were lower in the fingolimod cohort (0.27) than in the glatiramer acetate cohort (0.55).
After adjusting for baseline differences, the researchers found that patients treated with fingolimod had a 61% reduced probability of having a relapse and 53% fewer relapses per year during the persistence period, compared with patients who switched to glatiramer acetate.
In a related study, Dr. Bergvall and colleagues used the same claims database to compare relapse rates among patients with MS with a history of relapses who were initiated on fingolimod versus interferon or glatiramer acetate.
This study included patients with one or more prescription or administration claims for fingolimod, any interferon, or glatiramer acetate during the same time frame as the previous study (between October 1, 2010, and September 30, 2011). Again, patients had to have an MS diagnosis code and one or more relapses in the 360 days before disease-modifying therapy was initiated and no claim for disease-modifying therapy in the previous 360 days. Patients with prior evidence of fingolimod and another disease-modifying therapy were preferentially assigned to the fingolimod cohort to preserve sample size.
The number of relapses observed while persistent on index disease-modifying therapy (period before a gap of more than 60 days or switch to another disease-modifying therapy) was measured for patients with a 540-day follow-up. The adjusted probability of having one or more relapse was estimated using a logistic regression model, and differences in relapse rates were assessed using a generalized linear model with a negative binomial distribution.
This study included 525 patients (128 on fingolimod and 397 on interferon or glatiramer acetate). Annualized relapse rates in the 360-day pre-index period were 1.70 and 1.26, respectively. In unadjusted analyses, the proportion of patients with one or more relapses during the persistence period was marginally lower in patients treated with fingolimod, compared with interferon or glatiramer acetate (31.3% vs 34.0%), despite a longer mean persistence period (382 vs 341 days, respectively). Annualized relapses over the persistence period were also lower in the fingolimod cohort (0.50), compared with the interferon or glatiramer acetate cohort (0.55) in unadjusted analyses.
After controlling for baseline differences, the investigators found that fingolimod was associated with a 52% reduced probability of experiencing a relapse and 50% fewer relapses, compared with interferon or glatiramer acetate. Point estimates from comparisons of fingolimod versus separate interferon and glatiramer acetate cohorts were identical (50% reduction in relapses).
—Glenn S. Williams
Vice President/Group Editor