Medical Marijuana Legalization and Prescription Medication Use in the Medicare Population
*Names in bold indicate Presenter
One issue that has received surprisingly little attention is the question of whether medical marijuana is actually being used clinically to any significant degree. To the extent that marijuana is used by physicians to manage the conditions for which it has clinical evidence, then one would expect it to be used primarily as a substitute for existing prescription medications - for patients who did not respond to prior therapy, or who respond better to marijuana. Nonetheless, there are no published studies that investigate whether the introduction of medical marijuana changes the prescribing patterns of FDA-approved prescription drugs used to treat the conditions listed above.
In this paper, we use data on all prescriptions filled by Medicare Part D enrollees in the U.S. from 2010 to 2012. The data is compiled at the physician level, and is merged to detailed geographic health care related data. In addition, we use a unique data source to identify which prescription drugs are used on- and off-label for the conditions in question. We use a series of difference-in-difference models to determine whether physicians operating in states with an MML have different overall, on-label, and off-label prescribing patterns for Medicare Part D enrollees than their counterparts in non-MML states. Finally, we discuss the implications for patient welfare and the social impact of medical marijuana policies.
 Given the underlying conditions, few patients would have been untreated in the absence of marijuana, so changes to the active patient population are not likely to be a first-order issue.