Exhibit 1 (Figure). Trends in Part D Enrollment (in Millions), by LIS Status and Reaching Catastrophic Coverage.

Source: Authors’ analysis of Centers for Medicare and Medicaid Services beneficiary summary file and prescription drug event files from a 100 percent sample of Medicare beneficiaries, 2007-2015.

Notes: The sample includes beneficiaries enrolled in stand-alone prescription drug plans or in Medicare Advantage plans that had prescription drug coverage. Low Income Subsidy (LIS) beneficiaries include those receiving both partial and full benefits; beneficiary LIS status was assigned according to their LIS eligibility status in the last month of enrollment in each year. Beneficiaries were categorized as reaching catastrophic coverage if they had one or more prescription drug claims that included spending in the catastrophic coverage benefit phase.