BMC Medical Research Methodology

Table 1 Design parameters for phase II and III TB trials

From: A multi-arm multi-stage clinical trial design for binary outcomes with application to tuberculosis

Design	Study		Overall*
Parameter	Phase II	Phase III
Primary outcome	Negative	Non-
	culture status	failure/relapse
Follow-up length	8 weeks**	18 months**
Significance level (1-sided)	2.5%	2.5%	0.1%
Power	80%	85%	68%
Control arm event rate	75%	90%
Treatment effect under H ₀	0%	-6% (NI margin)
Target treatment effect (H ₁)	13%	0%
Allocation ratio (E:C)	1:1	1:1
Attrition rate	15%	20%
Required sample size***	320	1122	1442

Design parameters for a phase II (based on Dorman et al. [10]) and a phase III (based on REMox [20]) TB trial. *Calculated assuming independence between trials. **An additional 6 week delay is typically required to determine culture status. ***Sample sizes estimated using equations (1) and (2). NI = non-inferiority.

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