A significant concern in the policy landscape of the U.S. opioid crisis is whether supply-side controls can reduce opioid prescribing without harmful substitution. We consider an unstudied policy: the federal Controlled Substance Act (CSA) restrictions placed in August 2014 on tramadol, the second most popular opioid medication. This was followed seven weeks later by CSA restrictions for hydrocodone combination products, the leading opioids on the market. Using regression discontinuity design (RDD) models, based on the timing of the (up-)scheduling changes, to explore spillover effects, we find that tightening prescribing restrictions on one opioid reduces its use, but increases prescribing of close competitors, leading to no reduction in total opioid prescriptions.This suggests that supply restrictions are not effective in reducing opioid prescribing the presence of close substitutes that remain unrestricted.
Keywords: Controlled substance act; Opioids; Prescribing.
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