Table 1.
Demographic and baseline disease characteristics
| Variable | n = 1,364 |
|---|---|
| Sex | |
| Female | 944 (69.3%) |
| Male | 418 (30.7%) |
| Mean ± SD age on diagnosis of MS, years | 29.6 ± 8.50 |
| Mean ± SD time since diagnosis of MS, years | 9.62 ± 5.65 |
| Mean ± SD age on starting natalizumab, years | 39.2 ± 8.95 |
| Clinical form of MS prior to starting natalizumab | |
| Relapsing–remitting | 1,173 (86.8%) |
| Secondary progressive | 178 (13.2%) |
| Prior MS treatments | |
| No | 95 (7.0%) |
| Yes | 1,268 (93%) |
| One prior treatment | 603 (44.2%) |
| Two prior treatments | 431 (31.6%) |
| >2 prior treatments | 234 (17.1%) |
| Interferon beta 1a SC | 655 (51.7%) |
| Interferon beta 1b SC | 447 (35.3%) |
| Interferon beta 1a IM | 364 (28.7%) |
| Glatiramer acetate | 330 (26.0%) |
| Immunosuppressants | 113 (8.9%) |
| Mitoxantrone | 98 (7.7%) |
| Methotrexate | 7 (0.6%) |
| Cyclophosphamide | 9 (0.7%) |
| Azathioprine | 4 (0.3%) |
| Other treatments | 120 (9.5%) |
| EDSS score in year prior to treatment | 3.0 (0.0–8.0) |
| Annualized relapse rate in year prior to starting natalizumab | 2.0 (1–14) |
| No. of T1 Gd-enhancing lesions prior to natalizumab | |
| 0 lesions | 530 (47.7%) |
| 1–5 lesions | 467 (42.0%) |
| 6–9 lesions | 49 (4.4%) |
| >9 lesions | 66 (5.9%) |
EDSS Expanded Disability Status Scale, IM intramuscular, MS multiple sclerosis, SC subcutaneous