Comparison of injection site pain and injection site reactions in relapsing-remitting multiple sclerosis patients treated with interferon beta-1a or 1b

This prospective, multicentre, international, observational, cohort study compared injection site pain (ISP) and injection site reactions (ISRS) between interferon beta-1b (IFNB-1b; Betaferon ®) 250 μg subcutaneously every other day and interferon beta-1a (IFNB-1a; Rebif®) 44 μg subcutaneously three times weekly in patients with relapsing-remitting MS. Patients started treatment within 3 months before recruitment and were on full dose of therapy at inclusion. Patients self-injected IFNB and self-assessed ISP for 15 consecutive injections immediately, 30 and 60 min after injection, using a visual analogue scale diary. Study staff assessed ISRS. Of 445 patients (valid cases), ~90% used autoinjectors. More patients were pain-free at all timepoints with IFNB-1b than with IFNB-1a (eg, 30 min: 42.6% versus 19.7%; P< 0.0001). The mean proportion of pain-free injections was greater for IFNB-1b (eg, 30 min: 79.0%) than for IFNB-1a (53.3%; P < 0.0001). The proportion of patients without ISRS was greater for IFNB-1b...