As compared with the rate of sustained virologic response in the group that received @ weeks of ledipasvir-sofosbuvir , the rate in the @-week group was @ percentage point higher ( @ % CI , -@ to @ ) and the rate in the group that received @ weeks of ledipasvir-sofosbuvir with ribavirin was @ percentage point lower ( @ % CI , -@ to @ ) ; these results indicated noninferiority of the @-week ledipasvir-sofosbuvir regimen , on the basis of a noninferiority margin of @ percentage points .