"Current estimates suggest that upward of 80% of the world’s population lacks access to basic pain relief [6]. Paradoxically, those 80% are mostly in poorer countries, and their need for pain relief is heightened by a relative absence of curative care such as surgery, or treatment for both communicable and non-communicable diseases causing pain (e.g., HIV/AIDS, cancer)[7]."


Nickerson, Jason W., and Attaran, Amir, "The Inadequate Treatment of Pain: Collateral Damage from the War on Drugs," PLoS Medicine (Cambridge, United Kingdom: Public Library of Science, Jan. 2012) Vol. 9, Issue 1, p. 1.