The Impact of Medicare Part D on Opioid Use Among Older Adults

Medical use of prescription opioids for pain has risen dramatically over the past two decades. This increase has coincided with a period of insurance coverage expansions, notably the establishment of the Medicare Part D prescription drug benefit in 2006. Access to insurance that reduces cost-sharing for prescription drugs has been shown to increase drug utilization (Ghosh et al. 2017), including in the specific case of Medicare Part D (Yin et al. 2008). We therefore examine the impact of Medicare Part D implementation on the treatment of pain among adults age 65 and older, and in particular the use of prescription opioids in this age group. Using a combined regression discontinuity and differences-in-differences design, we use data from the National Ambulatory Medical Care Survey (NAMCS) to compare the incidence of pain diagnoses and prescription opioid use for non-disabled adults just below and above age 65, both before and after the roll-out of Medicare Part D in 2006. This allows us to characterize how pain management in older adults changes around the time of Medicare enrollment, and whether Part D had any further incremental impact on prescription opioid use. We find that the probability of being diagnosed with a pain condition increases when individuals turn 65 (and hence become eligible for Medicare) after the introduction of Part D in 2006, but there is no significant increase in the probability of being prescribed an opioid. We then provide descriptive evidence that the growth in opioid utilization among the Medicare-eligible is due to the stock of opioid users aging into Medicare, as opposed to the onset of Medicare eligibility at age 65.