Intramuscular interferon beta-1 was the first-line MS treatment with the highest adherence rate; natalizumab was the second-line treatment with the highest adherence rate and it had the lowest rate of patients switching to a third drug, researchers found.
SAN ANTONIO—Patients may adhere more to intramuscular (IM) interferon beta-1a than to other first-line disease-modifying therapies (DMTs) for multiple sclerosis (MS), according to a study presented at the 24th Annual Meeting of the Consortium of Multiple Sclerosis Centers.
“These results may be attributable to less frequent administration required for IM interferon beta-1a,” reported Rachel Halpern, PhD, of i3 Innovus, Eden Prairie, Minnesota, and colleagues. “Multiple factors are considered when selecting a first-line DMT for MS; given the importance of adherence in the management of MS, adherence should be one of those factors.”
Dr. Halpern’s team also performed analyses on second-line treatments and found that natalizumab was associated with the highest rate of patient adherence and the lowest rate of patients who switched to a third treatment. Like IM interferon beta-1a, natalizumab requires relatively infrequent administration.
The first-line and second-line studies were based on medical and pharmacy claims data and included both unadjusted analyses and regression analyses with adjustment for demographic and pre-index clinical characteristics. Adherence was defined as a medication-possession ratio of at least 80%, and persistence was defined as the “number of days until the earlier of last DMT claim before a minimum 60-day gap in therapy or last DMT claim during postindex.”
First-Line Treatments
The first-line study included 2,305 patients initiating treatment by taking IM interferon beta-1a once weekly, 894 taking subcutaneous (SC) interferon beta-1b every other day, 2,270 taking glatiramer acetate daily, and 1,211 taking SC interferon beta-1a three times weekly.
The unadjusted adherence rates were 62.3% for IM interferon beta-1a, 52.2% for SC interferon beta-1b, 55.4% for glatiramer acetate, and 58.5% for SC interferon beta-1a. Compared with IM interferon beta-1a, all the other treatments had significantly lower adjusted odds of adherence, at 0.66 for SC interferon beta-1b, 0.75 for glatiramer acetate, and 0.84 for SC interferon beta-1a.
The number of mean persistence days was 508 for IM interferon beta-1a, 482 for SC interferon beta-1b, and 471 for both glatiramer acetate and SC interferon beta-1a. In addition, the regression-adjusted persistence failure ratio of SC interferon beta-1a relative to IM interferon beta-1a was significantly high, at 1.12.
Second-Line Treatments
Second-line treatment analyses included 288 patients taking natalizumab, 429 taking IM interferon beta-1a, 415 taking SC interferon beta-1b, 1,067 taking glatiramer acetate, and 872 taking SC interferon beta-1a. Among these groups, the unadjusted adherence rates were 74.7% for natalizumab, 60.8% for IM interferon beta-1a, 55.4% for SC interferon beta-1b, 54.6% for glatiramer acetate, and 60.3% for SC interferon beta-1a. Adjusted odds of adherence relative to natalizumab were significantly lower for all the other drugs, at 0.56 for IM interferon beta-1a, 0.43 for SC interferon beta-1b, 0.42 for glatiramer acetate, and 0.54 for SC interferon beta-1a. Furthermore, SC interferon beta-1b, glatiramer acetate, and SC interferon beta-1a had significantly higher regression-adjusted persistence failure ratios relative to natalizumab, at 1.27, 1.27, and 1.24, respectively.
In the switching analysis, 10.4% of patients taking natalizumab, 23.5% of those taking IM interferon beta-1a, 23.1% of those taking SC interferon beta-1b, 16.9% of those on glatiramer acetate, and 21.8% of those taking SC interferon beta-1a switched to a third drug. Regression-adjusted switching relative to natalizumab was significantly more likely for IM interferon beta-1a, SC interferon beta-1b, and SC interferon beta-1a, at 1.74, 1.77, and 1.62, respectively. “Switching between DMTs often indicates problems with tolerance or effectiveness,” the researchers noted.
—Jack Baney