Patients were randomly assigned in a @:@ ratio to receive coformulated ABT-@ / r-ombitasvir ( at a once-daily dose of @ mg of ABT-@ , @ mg of ritonavir , and @ mg of ombitasvir ) and dasabuvir ( @ mg twice daily ) with ribavirin ( @ or @ mg daily ) or matching placebos during the @-week double-blind period .