Table 2

Numbers of patients/arm needed to perform PG trials with statistical powers of 80% or 90% to detect treatment effects ranging from 50% to 80%

Treatment effectsNo of scansStatistical power
80%90%
Group AGroup BGroup CGroup AGroup BGroup C
50%312585152150100182
61187014114085162
60%375551009870116
66542948555112
70%3483460645080
6402758583573
80%3282036403049
6241634352245
  • Group A: patients with RRMS not selected for MRI activity at entry;

  • Group B: patients with RRMS selected for MRI activity at entry;

  • Group C: patients with SPMS not selected for MRI activity at entry.

  • For further details and statistical analysis: see text.