Medicare Advantage coverage restrictions for the costliest physician-administered drugs

To examine the use of step therapy, prior authorization, and Part D formulary exclusion by 4 large Medicare Advantage (MA) insurers to manage 20 physician-administered drugs with the highest total Medicare expenditures (top 20 drugs).

We collected data for United Healthcare, CVS/Aetna, Humana, and Kaiser plans to create a database of 2020 Part B coverage restrictions and conducted a retrospective analysis of 2018-2020 Part D formularies.

For each insurer, we calculated the number of top 20 physician-administered drugs subject to prior authorization and step therapy. For physician-administered drugs for which there were no similar or interchangeable alternatives, we examined which insurers required prior authorization or step therapy. Finally, we examined whether insurers restricted access to physician-administered drugs by reducing coverage on Part D formularies.

Of the top 20 physician-administered drugs, 17 were subject to prior authorization and 10 were subject to step therapy by at least 1 insurer. For 5 physician-administered drugs without a similar or interchangeable alternative, none were subject to step therapy and all were subject to prior authorization by at least 1 insurer. Across the 4 insurers, 16 physician-administered drugs were covered on all or some of the Part D formularies in 2018, which decreased to 6 in 2020.

Four large MA insurers managed access to expensive physician-administered drugs with a combination of prior authorization, step therapy, and Part D formulary design. When a low-cost alternative exists, these tools can help reduce wasteful spending, but the administrative barriers may also reduce access.