With regard to weak opioids tramadol is the treatment of choice in most European countries. Codeine is most frequently used in the UK.

  Source: Physician interviews conducted by GFK Healthcare, March - May 2009
Focussing on severe chronic low back pain; you mentioned that you treat patients with severe pain due to severe chronic low back pain. Now think in your last 100 patients with this indication: How many of your patients did you treat with the following agents?