Evaluation of Effectiveness and Tolerability of Tapentadol Hydrochloride in Subjects With Severe Pain Due to Osteoarthritis Taking Either WHO Step I or Step II Analgesics or no Regular Analgesic

"Tapentadol Prolonged Release (PR) Titration and Optimal Dose Period: Starting at 50 mg Tapentadol PR twice daily, adjusting at 50 mg PR steps (upwards or downwards) as necessary to achieve a balance between pain relief and a satisfactory level of tolerability. Participants were not permitted to exceed 500 mg of Tapentadol per day.~Maintenance Period: Participants continuing on the dose established in the previous period."