Procedures In the control arm, patients received a weak opioid, either tramadol (maximum dose 100 mg qds) or codeine (maximum dose 60 mg qds), the choice of which, along with the starting dose, was made by the local investigator. Breakthrough analgesics (either weak or strong opioids) were not permitted in the control arm as patients were already on a maximum recommended dose of a weak opioid. The maximum doses and exclusion of breakthrough use were in line with WHO guidance.