Utilization of peginterferon-β-1a in the real-world practice for relapsing-remitting multiple sclerosis

Objective: Peginterferon β-1a (PEG-IFN-β-1a) is the most recent interferon beta formulation approved for treating relapsing-remitting multiple sclerosis (RRMS). We aim to describe the real-world utilization of PEG-IFN-β-1a in RRMS and compare it with other injectable disease-modifying therapies (DMTs). Patients and methods: In this population-based study, we used 2015-2019 routinely collected healthcare data of the Campania region of Italy from National Healthcare System DMT prescriptions, inpatient and outpatient clinical records of hospitals in Campania, and the Federico II University MS clinical registry for a subset of patients. We included individuals with RRMS receiving new prescriptions of PEG-IFN-β-1a [n=281; age = 38.8±12.3 years; females=70.5%; disease duration = 8.4±8.3 years; Expanded Disability Status Scale (EDSS) at baseline=2.0 (1.0-6.5)], glatiramer acetate [n=751; age = 46.0±11.4 years; females=67.1%; disease duration = 9.8±8.2 years; EDSS=4.0 (1.5-8.5)], and subcutaneous (SC) IFN-β-1a [n=1,226; age = 39.7±11.7 years; females=66.5%; disease duration = 8.2±6.5 years; EDSS 2.5 (1.5-6.5)]. Adherence [medication possession ratio (MPR)], escalation to more effective DMTs, hospitalization rates and costs were measured. We used mixed-effect linear regression models (for adherence, hospitalization rates and costs) and Cox regression models (for escalation) to assess differences between PEG-IFN-β-1a (statistical reference), glatiramer acetate, and SC IFN-β-1a. All models included age, sex, previous treatment/untreated, year of treatment initiation, treatment duration, and adherence as covariates. Results: Adherence was lower in glatiramer acetate (MPR = 0.91±0.1; Coeff=-0.11; p<0.01), and IFN-β-1a (MPR = 0.92±0.1; Coeff=-0.08; p<0.01), compared with PEG-IFN-β-1a (MPR = 1.01±0.1). The probability of escalating to more effective DMTs was higher for glatiramer acetate (14.9%; HR=4.09; p<0.01) and IFN-β-1a (9.1%; HR=3.35; p=0.01), compared with PEG-IFN-β-1a (4.9%). No differences in annualized hospitalization rates were identified between glatiramer acetate [annualized hospitalization rates (AHR) = 0.05±0.30; Coeff=0.02; p=0.31), IFN-β-1a (AHR = 0.02±0.21; Coeff=0.01; p=0.97], and PEG-IFN-β-1a (AHR = 0.02±0.24); however, monthly costs for MS admissions were higher for glatiramer acetate (€49.45±€195.27; Coeff=-29.89; p=0.03), compared with IFN-β-1a (€29.42±€47.83; Coeff=6.79; p=0.61), and PEG-IFN-β-1a (€23.91±€43.90). Conclusions: SC PEG-IFN-β-1a and IFN-β-1a were used in relatively similar populations, while glatiramer acetate was preferred in older and more disabled patients. PEG-IFN-β-1a was associated with higher adherence and lower escalation rates toward more effective (and costly) DMTs.