Efficacy and safety of interferon beta-1b sc in older RRMS patients--a posthoc analysis of the BEYOND study

Evidence of a significant improvement of IFNB-1b in clinical severity in the older population with RRMS has not been established so far. The aim of this exploratory post hoc analysis of the 250 mcg IFNB-1b group of the BEYOND study is to compare the efficacy and safety of older versus younger patients using a cut-off at the age of 50 and at the age of 40, respectively. There was no difference between age groups in adjusted relapse risk (age 50 cut-off: P = 0.482, age 40 cut-off: P = 0.073) nor in adjusted time to confirmed EDSS progression (age 50 cut-off: P = 0.096, age 40 cut-off: P = 0.189). There were no significant differences between patients <50 and ≥ 50 years in the adjusted annualized relapse rate (P = 0.285), whereas relapse rate was higher in the <40 as compared to the ≥ 40 group (P = 0.024). The proportion of patients with confirmed disability progression was not significantly different for the 50 cutoff (P = 0.148), whereas significantly fewer <40 than ≥ 40 patients had disability progression (P = 0.047). Only minor differences in adverse event frequencies between the age groups for the two cut-offs were seen. These results indicate that IFNB-1b is as efficacious and safe in patients ≥ 50 years as <50 years of age.