The rates of sustained virologic response were high in all treatment groups : @ % ( @ % confidence interval -LSB- CI -RSB- , @ to @ ) in the group that received @ weeks of ledipasvir-sofosbuvir ; @ % ( @ % CI , @ to @ ) in the group that received @ weeks of ledipasvir-sofosbuvir and ribavirin ; @ % ( @ % CI , @ to @ ) in the group that received @ weeks of ledipasvir-sofosbuvir ; and @ % ( @ % CI , @ to @ ) in the group that received @ weeks of ledipasvir-sofosbuvir and ribavirin .