Table 2 Duration of natalizumab exposure and treatment discontinuation

Duration of natalizumab exposure^a

N = 85

 Mean ± SD, duration, years

2.30 ± 1.12

 Median (range) duration, years

1.92 (0.9, 5.4)

 Duration, n (%)

  ≤ 1 year

1 (1.2)^b

  > 1 to ≤ 2 years

48 (56.5)

  > 2 to ≤ 3 years

17 (20.0)

  > 3 to ≤ 4 years

11 (12.9)

  > 4 to ≤ 5 years

3 (3.5)

  ≥ 5 years

5 (5.9)

Treatment discontinuation

n = 58

 Timing of discontinuation, n (%)

  ≤ 1 year

1 (1.7)^b

  > 1 to ≤ 2 years

42 (72.4)

  > 2 to ≤ 3 years

10 (17.2)

  > 3 to ≤ 4 years

2 (3.4)

  > 4 to ≤ 5 years

2 (3.4)

  ≥ 5 years

1 (1.7)

 Reasons for treatment discontinuation, n (%)

  Concerns about the risk of PML

45 (77.6)

  Pregnancy and planning

7 (12.1)

  Moving and change of hospital

4 (6.9)

  Insufficient effect and worsening of disability

1 (1.7)

  Use of contraindicated drug

1 (1.7)