Table 3.

Power for QALY Test of Equality for Utility = 0.5 and HR = 1.00 and a Basic Toxicity Rate of 10% in One Arm

	Difference in Percent of Days With Toxicity
N Per Group	Equal (10% of Days)	50% More (15% of Days)	75% More (17.5% of Days)	Double (20% of Days)	Triple (30% of Days)	Quadruple (40% of Days)
50	5	6	6	6	9	14
100	5	6	6	7	13	24
150	5	6	7	8	17	31
200	5	6	7	8	20	41
300	5	7	7	10	26	57
500	4	7	8	14	42	78
1000	4	8	12	22	72	98

QALY = quality-adjusted life year.

Values in bold indicate at least 80% power.

If the overall survival time is the same, you need a quadruple of toxicity rates (from 10% to 40%) and samples of 500 events to have 80% power to detect a difference in QALYs.