Characteristics of Patients Switching to Subcutaneous Peginterferon Beta-1a Vs. Subcutaneous Interferon Beta-1a in the United States

Background: Peginterferon beta-1a (pegIFN) is a pegylated interferon beta-1a with a prolonged half-life, allowing for reduced dosing frequency (once every 2 weeks) vs subcutaneous interferon beta-1a three times per week (SC IFN). Since the US launch of pegIFN in 2014, its use by US healthcare providers (HCPs) in clinical practice has not been well characterized.

Objectives: To describe the demographics and clinical characteristics of multiple sclerosis (MS) patients previously on another MS disease modifying therapy (DMT) and initiating pegIFN or SC IFN in the US using administrative claims data post-pegIFN approval.

Methods: We analyzed MS patients 18-64 years old in the Truven Commercially-Insured Marketscan Database previously on a DMT and initiating pegIFN or SC IFN on or after US commercial availability of pegIFN (November 3, 2014) until the database cutoff of December 31, 2015. Index date for the respective cohorts was defined as the date of the first pegIFN or SC IFN claim. Continuous enrollment in the database for one year prior (pre-index period) to index date was required. Patients must have had a claim for a prior DMT during the pre-index period (pre-treated). Demographic and clinical characteristics were evaluated over the one-year pre-index date.

Results: We identified 520 pre-treated patients initiating pegIFN and 100 initiating SC IFN during the study period. Patients initiating pegIFN were older than those initiating SC IFN (49.6 vs. 42.8 years, p<0.0001). Most patients who initiated pegIFN were previously treated with intramuscular (IM) IFN once weekly (60.8%), while only 6.0% of SC IFN patients were previously treated with IM IFN (p<0.0001). Annualized relapse rate in the one-year pre-index period (prior to initiation) was significantly lower for patients initiating pegIFN vs. those initiating SC IFN (0.29 vs. 0.74, p<0.0001). Consistent with these results, an MS severity measure (based on prevalence of MS-specific comorbidities in the dataset) was also significantly lower for patients transitioning to pegIFN vs SC IFN (3.43 vs. 5.39, p<0.0001) in the pre-index period.

Conclusions: This real-world, observational study provides insights into the utilization of pegIFN and SC IFN in patients previously treated with DMTs. The majority of patients who initiated pegIFN utilized IM IFN once weekly previously. Overall, pre-treated SC IFN patients were younger and exhibited signs of more severe MS on their prior DMT than those transitioning to pegIFN.