From “Does Prescription Drug Coverage Increase Opioid Abuse? Evidence from Medicare Part D,” by Rosalie Liccardo Pacula, David Powell, and Erin Taylor:
We find that one particular insurance expansion that focuses exclusively on expansion of prescription drug benefits, i.e. Medicare Part D, has indeed been a significant contributor to the rise in opioid sales and opioid treatment admissions since its implementation in 2006. […] Importantly, however, we find that abuse, as indicated by treatment admissions, rises more for the non-elderly (and in the case of the treatment data), nondisabled population. In other words, we find evidence of diversion from those with legitimate medical need (i.e. the Medicare population) to other individuals. We estimate that an additional 10% increase in Medicare Part D enrollment is associated with a 4% increase in opioid prescriptions in the state, and an 8% increase in opioid treatment admissions.