"Conventional wisdom suggests that the abuse potential of opioid analgesics is such that increases in medical use of these drugs will lead inevitably to increases in their abuse. The data from this study with respect to the opioids in the class of morphine provide no support for this hypothesis. The present trend of increasing medical use of opioid analgesics to treat pain does not appear to be contributing to increases in the health consequences of opioid analgesic abuse."

Source

Joranson, David E., MSSW, Karen M. Ryan, MA, Aaron M. Gilson, PhD, June L. Dahl, PhD, "Trends in Medical Use and Abuse of Opioid Analgesics," Journal of the American Medical Association, Vol. 283, No. 13, April 5, 2000, p. 1713.
http://jama.jamanetwork.com/a…