Table 4

Numbers of patients/arm needed to perform BVT trials with statistical powers of 80% or 90% to detect treatment effects ranging from 20% to 50%

Treatment effects		No of scans^4-150		Statistical powers
				80%				90%
				Group A	Group B			Group C	Group A	Group B	Group C
20%	3	80	60	82		108	75	100
	6	48	35	62		60	52	72

30%	3	42	30	50		50	40	67
	6	22	21	35		32	32	44

40%	3	26	19	29		35	28	40
	6	14	12	20		20	18	28

50%	3	18	12	21		25	18	29
	6	12	9	16		17	12	21

↵4-150 These are numbers of scans for each of the portions of the trial.
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.