1. Efficacy and safety of extended-release, once-daily tramadol in chronic pain: a randomized 12-week clinical trial in osteoarthritis of the knee 
Najib Babul, PharmD, Robert Noveck, MD, Howard Chipman, MD, Sanford H Roth, MD, Theophilus Gana, MD, PhD, Kenneth Albert, PhD 
Journal of Pain and Symptom Management 
Volume 28, Issue 1, Pages (July 2004)
DOI: /j.jpainsymman

2. Figure 1
Disposition of patients over 12 weeks, following randomization to tramadol ER or placebo.
Journal of Pain and Symptom Management  , 59-71DOI: ( /j.jpainsymman )

3. Figure 2
Mean change from baseline to Weeks 1, 2, 4, 8, and 12 in Arthritis Pain Intensity VAS score obtained at clinic visits (primary variable) for tramadol ER and placebo. Data in parentheses are percent change from baseline at each visit.
Journal of Pain and Symptom Management  , 59-71DOI: ( /j.jpainsymman )

4. Figure 3
Mean (± SE) change in the Daily Arthritis Pain Intensity VAS scores over 12 weeks obtained from patient diaries for the tramadol ER and placebo.
Journal of Pain and Symptom Management  , 59-71DOI: ( /j.jpainsymman )

5. Figure 4
Mean percent change from baseline to Week 12 in WOMAC OA Index (pain, stiffness and physical function, and pain walking on a flat surface), WOMAC OA Composite Index, and Patient Global Assessment of OA for the tramadol ER and placebo. Data in parentheses are change from baseline to Week 12 expressed in mm.
Journal of Pain and Symptom Management  , 59-71DOI: ( /j.jpainsymman )