"We determined per capita need of strong opioids for pain related to three important pain causes for 188 countries. These needs were extrapolated to the needs for all the various types of pain by using an adequacy level derived from the top 20 countries in the Human Development Index. By comparing with the actual consumption levels for relevant strong opioid analgesics, we were able to estimate the level of adequacy of opioid consumption for each country. Good access to pain management is rather the exception than the rule: 5.5 billion people (83% of the world’s population) live in countries with low to nonexistent access, 250 million (4%) have moderate access, and only 460 million people (7%) have adequate access. Insufficient data are available for 430 million (7%). The consumption of opioid analgesics is inadequate to provide sufficient pain relief around the world. Only the populations of some industrialized countries have good access."

Source

Marie-Josephine Seya, Susanne F. A. M. Gelders, Obianuju Uzoma Achara, Barbara Milani, and Willem Karel Scholten, "A First Comparison Between the Consumption of and the Need for Opioid Analgesics at Country, Regional, and Global Levels," Journal of Pain & Palliative Care Pharmacotherapy. 2011;25:6–18. ISSN: 1536-0288 print / 1536-0539 online. DOI: 10.3109/15360288.2010.536307
http://apps.who.int/medicined…