Measures of clinical disease activity from baseline to PRISMS-15 in the lowest (MIN) and highest (MAX) quartiles, by cumulative total dose of sc IFN β-1a and by time receiving sc IFN β-1a per 5 years
| Cumulative dose of sc IFN β-1a | ||||
|---|---|---|---|---|
| Outcomes at year 15 | MIN (n=73) | MAX (n=72) | OR* (95% CI) MAX vs MIN | Odds ratio† (95% CI) per 5 years of sc IFN β-1a treatment |
| Mean (95% CI) annualised relapse rate‡ | 0.50 (0.46 to 0.54) | 0.37 (0.33 to 0.40) | – | – |
| Mean (SD) number of relapses | 7.8 (5.8) | 5.8 (4.8) | – | – |
| Relapse-free, n (%) | 5 (6.8) | 5 (6.9) | – | – |
| 3-month confirmed EDSS progression, n (%) | 50 (68.5) | 38 (52.8) | – | – |
| Mean (SD) change in EDSS score | 2.53 (2.01) | 1.15 (1.52) | – | – |
| EDSS ≥4, n (%) | 37 (60.7)§ | 21 (31.8)¶ | 0.30 (0.15 to 0.63) | 0.75 (0.58 to 0.96) |
| EDSS ≥6, n (%) | 38 (52.1) | 10 (13.9) | 0.15 (0.07 to 0.33) | 0.60 (0.47 to 0.77) |
| ≤5 relapses and EDSS <4,** n (%) | 11 (16.9)†† | 25 (35.7)‡‡ | 2.73 (1.21 to 6.14) | 1.39 (1.05 to 1.83) |
| ≤5 relapses and EDSS <6,§§ n (%) | 12 (16.4) | 34 (47.2) | 4.55 (2.10 to 9.85) | 1.68 (1.29 to 2.18) |
| Converted to SPMS, n (%) | 38 (52.1) | 15 (20.8) | – | – |
*MIN quartile as a reference category; logistic regression model.
†Logistic regression model.
‡Poisson regression model with factors for quartile of cumulative dose of sc IFN β-1a. The log of total observation time in years from PRISMS baseline to PRISMS-15 was used as the offset variable.
§n=61.
¶n=66.
**Patients with baseline EDSS ≥4 are counted as missing on the EDSS component of the variable.
††n=65.
‡‡n=70.
§§Patients with baseline EDSS ≥6 are counted as missing on the EDSS component of the variable.
EDSS, Expanded Disability Status Scale; IFN, interferon; sc, subcutaneous; SPMS, secondary progressive multiple sclerosis.