Background Peginterferon beta-1a (PEGIFNβ-1a) is administered subcutaneously biweekly, which is an advantage over other treatment schedules used in multiple sclerosis (MS) patients.

Purpose To compare treatment satisfaction in MS patients treated with interferon beta-1a (IFNβ-1a) intramuscularly (30 µg weekly) after switching to PEGIFNβ-1a 125 µg administered subcutaneously every 2 weeks.

Material and methods This was a prospective multicentre study. Adult MS patients switching from weekly intramuscular IFNβ-1a to biweekly PEGIFNβ-1a were included. Patient satisfaction was measured according to the Treatment Satis­faction Questionnaire for Medication (TSQM), which consists of 14 items scaled on a 5–7 point bipolar scale. Items are combined into four summary scores: effectiveness, side effects, convenience and overall satisfaction. Higher scores imply higher satisfaction. The Wilcoxon signed rank test was used for evaluating the differences. The study was approved by the ethics committee.

Results 35 patients were included. Mean age (±SD) was 44.9±8.6 years and 74.4% were women. Intramuscular IFNβ-1a was the firstline treatment for 88.6% of patients. Treatment duration before change was 64.4±50.5 months. Overall satisfaction and satisfaction in terms of effectiveness were higher for IFNβ-1a IM. Convenience was better evaluated for PEGIFNβ-1a. Side effects were reported in a similar percentage (table). 11.4% of patients returned to intramuscular IFNβ-1a.

Conclusion Switching from intramuscular IFNβ-1a to PEGIFNβ-1a resulted in better convenience and a similar reported rate of adverse effects although overall satisfaction was lower.

No conflict of interest