Interferon β-1a subcutaneously 3 times/week clinical outcome in relapsing multiple sclerosis in Finland.

Prognostic factors and long-term treatment response of interferon β-1a s.c tiw has not been studied in a real-life clinical cohort in Finland. The aim of the paper was to evaluate long-term treatment response, prognostic clinical factors and adherence among interferon β-1a s.c tiw treated patients in Finland. A retrospective review of medical records was performed. Confirmed relapsing multiple sclerosis patients treated with interferon β-1a s.c tiw 22μg or 44μg as their first treatment, from 1996 to 2010 in Western Finland, were included. Longitudinal generalized linear regression models were applied to assess risk of disability progression, using Expanded Disability Status Scale (EDSS), during the treatment period. Odd's ratios with 95% confidence intervals (95% CI) were calculated for risk factors: gender, age at diagnosis, treatment delay, dose, baseline EDSS and EDSS change in one year. Kaplan-Meier was applied to study median time to discontinuation. Mean duration of treatment in 293 cases was 2.9 years (min 0.04, max 13.5). EDSS increase vs. no increase in one-year carried a significant risk for long-term disability progression (1.20, 1.08-1.33). Older age, defined by a 10-year increase in age at diagnosis (1.43, 1.07-1.91) and one-year delay to treatment start showed an increased risk for disability progression (1.05, 0.99-1.11), but gender (0.66, 0.38-1.15) or initial dose (1.00, 0.45-2.25) showed no risk. Treatment was stopped in 37% due to disease activation at median of 1.7 years, and in 25% due to side effects at 9.3 months. Our results show that young age, a short delay to treatment start and slower disability progression were identified as factors for better outcome among cases with interferon β-1a s.c tiw as their first disease modifying treatment.