Patients were randomly assigned in a 3:1 ratio to receive coformulated ABT-450 / r-ombitasvir ( at a once-daily dose of 150 mg of ABT-450 , 100 mg of ritonavir , and 25 mg of ombitasvir ) and dasabuvir ( 250 mg twice daily ) with ribavirin ( 1000 or 1200 mg daily ) or matching placebos during the 12-week double-blind period .