Patient Characteristics Vary Across Part D Protected Drug Classes

Health Highlights

Current Medicare Part D policy requires sponsors to cover with limited exceptions “all or substantially all” drugs in six “protected” classes: antidepressants, antipsychotics, anticonvulsants, immunosuppressants for treatment of transplant rejection, antiretrovirals and antineoplastics.1 Overall, in 2016, 18 million Part D enrollees took at least one drug in one of the six protected classes, and the total spend for protected class drugs was 19 percent of total Part D spend. In the CY 2020 Medicare Part D proposed rule, the Centers for Medicare & Medicaid Services (CMS) proposed to give Part D sponsors more tools such as prior authorization and step therapy to manage formularies within protected classes.2

Impacts of these proposed changes on patients are likely to depend on the types of patients prescribed drugs in these classes. Manatt Health found considerable differences in patient characteristics among the protected classes in its analysis of 2016 Part D drug event data. This suggests that proposed changes could have widely different impacts on patients depending on which protected class includes their medication therapy.

The number of enrollees who may be impacted by changes varies significantly from class to class.

  • Antidepressants had the largest number of enrollees. More than 12.36 million Part D enrollees used drugs in this class in 2016 compared to only 180,000 enrollees for immunosuppressants, the class with the smallest number of enrollees.

There is also significant variance in the age of patients.

  • Patients using antiretroviral drugs tended to be younger than patients using antineoplastics, with an average age of 57 years compared to 73 years, respectively.

Some classes have a far more significant user base among dual eligible Part D enrollees (those eligible for both Medicare and Medicaid).

  • Dual eligibles, as measured by at least one month of dual eligibility status in 2016, constituted a larger proportion of those using antiretroviral drugs (68 percent) and antipsychotics (60 percent) compared with the four other protected classes, ranging from anticonvulsants (42 percent) and antidepressants (36 percent) to immunosuppressants (30 percent) and antineoplastics (26 percent).

The same variation can be seen in the use of protected class drugs among those Part D enrollees who qualify for Medicare because of disability.

  • Just over two-thirds of enrollees using antiretroviral drugs currently qualify for Medicare through disability. In contrast, more than half of the enrollees qualify for Medicare through traditional age criteria (Old Age and Survivors Insurance) for all other protected Part D drug classes.

For five of the six protected classes, 25 percent of Part D enrollees who use protected class drugs accounted for 80 percent or more of the total spend in each protected class.

  • Specifically, 25 percent of enrollees who use antineoplastics accounted for 99 percent of spend in antineoplastics; 25 percent of enrollees who use antipsychotics accounted for 93 percent of the Part D spend in that protected class. In contrast, 25 percent of enrollees who use antiretrovirals accounted for 41 percent of spend in that protected class.

Patients using protected class drugs were enrolled in stand-alone Part D Plans (PDPs) and Medicare Advantage Part D Plans (MA-PDPs) in similar proportions as the general Medicare population, regardless of protected class. In 2016, about 60 percent of Part D enrollees were in PDPs and 40 percent in MA-PDPs.3

1CMS. Medicare Prescription Drug Benefit Manual Chapter 6, Section 30.2.5. Retrieved on January 16, 2019, from

2Fed. Reg. 83(231). 62152. [November 30, 2018]. Retrieved on January 16, 2019, from

3Kaiser Family Foundation (KFF). (2016). Medicare Part D in 2016 and Trends Over Time. Retrieved on January 16, 2019, from



pursuant to New York DR 2-101(f)

© 2024 Manatt, Phelps & Phillips, LLP.

All rights reserved