Patients who completed titration and , during the last 3 days of titration , had mean pain intensity < 5 ( based on twice-daily ratings ) and mean rescue medication use = 20 mg/day continued into a 4-week maintenance period ; patients who received morphine CR during titration continued taking morphine CR , and those who received tapentadol PR were re-randomized ( 1:1 ) to tapentadol PR or placebo bid .