1. Long-Term Opioid Therapy for Chronic Noncancer Pain: A Systematic Review and Meta-Analysis of Efficacy and Safety 
Meredith Noble, MS, Stephen J. Tregear, DPhil, Jonathan R. Treadwell, PhD, Karen Schoelles, MD, SM 
Journal of Pain and Symptom Management 
Volume 35, Issue 2, Pages (February 2008)
DOI: /j.jpainsymman
Copyright © 2008 U.S. Cancer Pain Relief Committee Terms and Conditions

2. Fig. 1 Flow diagram of study selection.
Journal of Pain and Symptom Management  , DOI: ( /j.jpainsymman )
Copyright © 2008 U.S. Cancer Pain Relief Committee Terms and Conditions

3. Fig. 2 Withdrawal from clinical trial due to adverse events.
Journal of Pain and Symptom Management  , DOI: ( /j.jpainsymman )
Copyright © 2008 U.S. Cancer Pain Relief Committee Terms and Conditions

4. Fig. 3 Withdrawal from clinical trial due to insufficient pain relief.
Journal of Pain and Symptom Management  , DOI: ( /j.jpainsymman )
Copyright © 2008 U.S. Cancer Pain Relief Committee Terms and Conditions