Table 1

Patient characteristics

Total nFemaleMaleMedian age (range)Median ∆t months (range)
IFNβ subgroup t1–t2170106 (62%)64 (38%)37 (16–58)13 (1–59)
NAT group t3–t4714500 (70%)214 (30%)37 (12–63)12 (1–38)
Blood donors144100 (69%)44 (31%)35 (18–63)
  • The analysed serum samples were obtained from patients with multiple sclerosis enrolled in the Swedish pharmacovigilance study for natalizumab (NAT). The interferon beta (IFNβ) subgroup is a subgroup of the NAT group defined by samples available prior to NAT therapy at time point 1 (t1) and t2. The NAT group consists of samples taken before NAT treatment, at t3 and during NAT treatment, at t4. Sex-matched and age-matched blood donors were included as a control group. Δt is duration of time in months between samples taken at t1–t2 and t3–t4.