Table 1.
Demographic and clinical characteristics of patients with multiple sclerosis initiating subcutaneous interferon β-1a, three times weekly, by discontinuation status
| Characteristics | sc IFN β-1a tiw | |||
|---|---|---|---|---|
| Total sample (N = 5956) | Discontinued (N = 2862) | |||
| n | % | n | % | |
| Female sex | 4447 | 74.7 | 2177 | 76.1 |
| Age, mean (SD) years | 44 (10.7) | 44 (10.8) | ||
| Region | ||||
| Northeast | 999 | 16.8 | 481 | 16.8 |
| North Central | 1764 | 29.6 | 766 | 26.8 |
| South | 2156 | 36.2 | 1066 | 37.2 |
| West | 968 | 16.3 | 517 | 18.1 |
| Unknown | 69 | 1.2 | 32 | 1.1 |
| Charlson comorbidity index | ||||
| Index = 0 | 3974 | 66.7 | 1887 | 65.9 |
| Index = 1 | 1102 | 18.5 | 552 | 19.3 |
| Index = 2 | 501 | 8.4 | 242 | 8.5 |
| Index ≥ 3 | 379 | 6.4 | 181 | 6.3 |
| Relapse per year, mean (SD) | 0.21 (0.57) | 0.25 (0.55) | ||
| High relapse (≥2 relapses)a | 271 | 4.6 | 154 | 5.4 |
| DMD use history | 2162 | 36.3 | 1143 | 39.9 |
| Treatment duration, median (IQR) months | 9 (3–22) | 6 (2–15) | ||
| Persistence | 5634 | 94.6 | 2645 | 92.4 |
| Adherence to treatment <80% (vs. ≥80%) | 3078 | 51.7 | 2691 | 94.0 |
| Baseline corticosteroid use | 2384 | 40.0 | 1194 | 41.7 |
| Follow-up | ||||
| NSAID use | 3221 | 54.1 | 1862 | 65.1 |
| Antidepressant use | 3020 | 50.7 | 1682 | 58.8 |
| Anxiolytic use | 1229 | 20.6 | 753 | 26.3 |
| Corticosteroid use | 2222 | 37.3 | 1362 | 47.6 |
DMD disease-modifying drug, NSAID non-steroidal anti-inflammatory drugs, IFN interferon, IQR, interquartile range, SC subcutaneous, SD standard deviation, Tiw three times a week
aHigh relapse activity defined as having ≥2 relapses in the first year prior to start of subcutaneous interferon β-1a, three times weekly