The design and statistical aspects of VIETNARMS: a strategic post-licensing trial of multiple oral direct-acting antiviral hepatitis C treatment strategies in Vietnam

Table 5 Group-specific cure rates and power for 1092 patients with an overall 95% cure rate

	Ribavirin group cure rate compared with 12 week standard treatment cure rate
	5% higher	2.5% higher	Equal
Group-specific cure rates:
Standard 12-week treatment groups	93.3%	95%	96.7%
Shortened treatment with ribavirin groups	98.3%	97.5%	96.7%
Shortened treatment without ribavirin groups	93.3%	92.5%	91.7%
Power for a:
5% non-inferiority margin for regimen comparison	99%	98%	97%
10% non-inferiority margin for strategy comparison	100%	100%	96%
5% absolute difference for ribavirin comparison	98%	95%	91%

Group-specific cure rates are such that overall cure rate in 1092 patients is 95%, ribavirin effect between shortened treatment groups is 5% and there is no effect of regimen. The effect of ribavirin in shortened treatment compared with standard treatment is varied to reflect uncertainties in the cure rates and to vary the no effect of strategy between standard treatment and shortened treatment without ribavirin, shortened treatment with ribavirin and pooled shortened treatment groups. Power is calculated with one-sided alpha of 0.05 for non-inferiority margins and two-sided alpha of 0.05 for superiority comparisons reflecting the design. Power assumes that no groups have been stopped during recruitment.

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