Table 2.

Relapse outcomes

Groups analyzedPatient group (relapse count per year*)Risk ratio of relapse (95% CI) and treatment comparison
* Estimated count from Poisson regression model with effects for treatments, center, and treatment-by-center interaction (interaction p values <0.001). Placebo/IFN = placebo years and treatment years combined; placebo = only placebo years considered; placebo/22 = placebo years and treatment years for placebo patients randomized to 22 mcg IFN-β-1a for PRISMS-4; placebo/44 = placebo years and treatment years for placebo patients randomized to 44 mcg IFN-β-1a for PRISMS-4; IFN = interferon; ITT = intent to treat.
Three-group (ITT), years 1–4Rx22 (0.80) vs placebo/IFN (1.02)0.76 (0.67, 0.86)p < 0.001
Rx44 (0.72) vs placebo/IFN (1.02)0.66 (0.58, 0.76)p < 0.001
Rx44 vs Rx220.88 (0.76, 1.01)p = 0.069
Four-group, years 1–4Rx22 (0.80) vs placebo/22 (0.99)0.76 (0.66, 0.89)p < 0.001
Rx44 (0.72) vs placebo/44 (1.06)0.70 (0.59, 0.82)p < 0.001
Rx44 vs Rx220.88 (0.76, 1.01)p = 0.069
Four-group, years 3–4Rx22 (0.64) vs placebo/22 (0.64)1.01 (0.80, 1.28)p = 0.946
Rx44 (0.52) vs placebo/44 (0.71)0.73 (0.58, 0.94)p = 0.014
Rx44 vs Rx220.79 (0.64, 0.97)p = 0.025