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Part D Plans Generally Include Drugs Commonly Used by Dual-Eligible Enrollees: 2023


This data snapshot fulfills for 2023 the annual reporting mandate from the Patient Protection and Affordable Care Act (ACA). The ACA requires OIG to conduct a study of the extent to which formularies used by Medicare Part D plans include drugs commonly used by full benefit dual eligible enrollees (i.e., individuals who are eligible for both Medicare and full Medicaid benefits). These individuals generally get drug coverage through Medicare Part D. Pursuant to the ACA, OIG must annually issue a study with recommendations as appropriate. This is the thirteenth study that OIG has produced to meet this mandate.


For this data snapshot, we determined whether the 445 unique formularies used by the 5,619 Part D plans operating in 2023 cover the 200 drugs most commonly used by dual-eligible enrollees. To create the list of the 200 drugs most commonly used by dual-eligible enrollees, we used the 2020 Medicare Current Beneficiary Survey—the most recent data available at the time of our study. Of the top 200 drugs, 195 are eligible for Part D prescription drug coverage, while 4 are excluded from coverage. One additional drug is eligible for Part D coverage, but we did not include it in our analysis because we could not confidently project the use of this drug to the entire dual-eligible enrollee population.


We found that dual-eligible enrollees—that is, individuals who are covered by both Medicare and Medicaid-have access to the majority of commonly used drugs in 2023 via their Part D plans, consistent with OIG's findings from previous years. A majority of the 445 Part D plan formularies covered almost all (at least 97 percent) of the drugs most commonly used by dual-eligible enrollees. Similar to all formularies, a majority of formularies used by Part D plans with premiums below the regional benchmark (92 of 130) covered at least 97 percent of the drugs commonly used by dual-eligible enrollees. Dual-eligible enrollees have several options if their plans do not cover specific drugs; however, these options may be burdensome and do not guarantee access to the drugs.


In general, dual-eligible enrollees have access to nearly all of the most commonly used drugs via their Part D plan formularies in 2023. A majority of these formularies covered almost all commonly used drugs, and only a small number of commonly used drugs were not covered by most formularies. These findings are largely unchanged from OIG's findings reported from 2011 through 2022. As mandated by the ACA, OIG will continue to monitor and produce annual reports on the extent to which Part D plan formularies cover drugs that dual-eligible enrollees commonly use. OIG has no recommendations at this time.