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Research and Innovation

Study: Medicare Part D Boosts Medication Adherence, Reduces Blood Pressure Risk

For Immediate Release

New research from North Carolina State University shows that implementation of Medicare Part D has increased the number of people taking their prescribed medications as directed – so-called “medication adherence” – and reduced the likelihood that newly covered beneficiaries develop high blood pressure.

“These findings highlight how important healthcare access is to health outcomes,” says Jeffrey Diebold, an assistant professor of public administration at NC State and author of a paper describing the work. “Given the amount of money we’re paying for Part D, it’s good to know there are tangible benefits.

“This is especially relevant in light of recent reforms and proposals put forth by presidential candidates, such as allowing the federal government to negotiate with drug companies on pharmaceutical prices, which would increase access to prescription coverage,” Diebold says.

Medicare is designed to provide health care coverage for all U.S. citizens over the age of 65. Medicare Part D, which was implemented in 2006, expanded prescription drug coverage for Medicare beneficiaries. Prior to Part D, approximately 30 percent of Medicare beneficiaries lacked prescription coverage and had to pay for prescription drugs out of pocket. Most of these individuals are now covered under Part D, meaning that they pay less for their prescription drugs.

“The implementation of Part D should have improved medication adherence, since the drugs became more affordable,” Diebold says. “I wanted to know if this happened, and whether Part D actually reduced health risks for seniors. Prior work had shown a decrease in hospitalization rates, but no one has looked at markers related to specific health outcomes.”

For the study, Diebold examined data from 2000 to 2010 on 1,700 Medicare beneficiaries. Specifically, Diebold looked at self-reported health status and incidence of new high blood pressure diagnoses. High blood pressure is not a disease in itself, but significantly increases a person’s risk for heart disease or stroke.

“I found a significant and sustained improvement in self-reported health outcomes after the implementation of Part D,” Diebold says. “I also found a 50 percent reduction in cost-related nonadherence to drug regimens. Before implementation, 14 percent of people reported disruptions to medication adherence due to the cost of prescription drugs, and that dropped to 7 percent after implementation.”

In addition, according to Diebold’s estimates, Part D is responsible for a 5.6 percent reduction in the prevalence of high blood pressure. The reduction in new diagnoses is responsible for this improvement.

The improvements were concentrated among those newly covered beneficiaries who were continuously enrolled in a Part D plan after the establishment of the program in 2006. Many of the conditions treated with medication require continuous use of the medication in order to be effective. By remaining covered, these individuals were more likely to take their medications as directed over time, which maximized their health benefits.

“These findings highlight the need to make coverage more affordable and more comprehensive,” Diebold says. “Recent provisions included in the Affordable Care Act should improve the program along each of these dimensions and build on the improvements evident in this analysis.”

The paper, “The Effects of Medicare Part D on Health Outcomes of Newly Covered Medicare Beneficiaries,” is published in Journals of Gerontology: Social Sciences.


Note to Editors: The study abstract follows.

“The Effects of Medicare Part D on Health Outcomes of Newly Covered Medicare Beneficiaries”

Author: Jeffrey Diebold, North Carolina State University

Published: May 6, Journals of Gerontology: Social Sciences

DOI: 10.1093/geronb/gbw030


Objectives: To estimate the impact of Medicare Part D on cost-related prescription nonadherence and health outcomes among the newly covered medicare beneficiaries.

Method: Difference-in-differences analyses of data from a balanced panel of Medicare beneficiaries observed in each wave of the Health and Retirement Study from 2000 to 2010 were carried out. The differences in the pre- and post-Part D changes in these outcomes are calculated for previously uncovered Part D enrollees and a comparison group of previously covered Medicare beneficiaries.

Results: The results from this analysis indicate that Part D reduced cost-related nonadherence rates among the newly covered by 7% points and that this decline was sustained through 2010. Part D was also associated with a 5%-point increase in the likelihood that a newly covered enrollee reported to be in good or better health and a 4%-point decline in the likelihood of being diagnosed with high blood pressure. These improvements were also sustained through 2010 but were only evident among those newly covered beneficiaries who remained enrolled in a Part D plan through 2010. However, there is insufficient evidence to conclude that Part D improved the blood pressure of newly covered, hypertensive beneficiaries.

Discussion: Part D has had a sustained impact on cost-related nonadherence rates and the health status of newly covered beneficiaries. However, the change in health status is conditional on remaining enrolled in a Part D plan over time.