Ask About Adherence: Q&A with PhRMA Foundation Young Investigator Adherence Grantee - Xian Shen

Q&A with Xian Shen, a 2015 PhRMA Foundation Young Investigator Adherence grantee about his research focused on improving medication adherence.

Amey Sutkowski
Samantha DoughertyJune 18, 2015

Ask About Adherence: Q&A with PhRMA Foundation Young Investigator Adherence Grantee - Xian Shen.


Ask About Adherence is a blog series featuring Q&A’s with experts in medication adherence. In this post, we speak with Xian Shen, a 2015 PhRMA Foundation Young Investigator Adherence grantee about her research focused on improving adherence in Medicare beneficiaries. 

Stay tuned for the next Q&A and be sure to share your thoughts in the comments section below. We’d love to hear from you on ways to improve medication adherence!


SAMANTHA DOUGHERTY: What are the objectives of your research?

XIAN SHEN: My doctoral dissertation work seeks to understand independent effects of Medicare Part D plan policies, beneficiary characteristics and regional factors on medication adherence for oral hypoglycemic agents (OHA), statins and renin angiotensin system (RAS) antagonists.This work is inspired by my research interests in Medicare Part D, and more importantly an ongoing debate regarding appropriateness of risk adjustment for adherence-based quality measures used in the Medicare Star Ratings Program. Ask-About-Adherence-Thumbnail

DOUGHERTY: How do you think your research will help to guide practical, real world solutions to the adherence problem?

SHEN: In 2015, Star Ratings are assigned to Medicare Part D contracts based on assessment of 13 quality measures, of which three are based on medication adherence for OHAs, statins and RAS antagonists. Currently, ratings for these three adherence-based quality measures are unadjusted for differences in beneficiary characteristics between contracts. The controversy lies in an unsolved question whether these adherence measures actually capture quality of a Medicare Part D contract in managing beneficiaries’ medication adherence or whether they are reflections of the mix of beneficiaries in that contract.  

In my opinion, the key to answering this question is to distinguish the effects of beneficiary characteristics, Medicare Part D plan policies and other realms of determinants such as regional factors in health care resources. However, it is challenging to do so using observational data as a result of selection bias. In my doctoral dissertation, I propose to address this challenge in the context of a natural experiment created by an auto-assignment process under Medicare that randomly assigns beneficiaries receiving low-income subsidies to benchmark Part D plans within their regions. Randomization balances both observable and unobservable beneficiary characteristics among plans, and creates a unique research opportunity for estimating plan, enrollee, and regional effects on medication adherence.

DOUGHERTY: How has/will the PhRMA Foundation grant advance your career in adherence research?

SHEN: With the support of the PhRMA Foundation grant, I am able to conduct cutting-edge research that will help to guide real-world solutions to adherence problems. Findings of this study will provide insights into how drug plan policies, such as utilization management tools and medication therapy management rules, contribute to individuals’ medication adherence. Additionally, findings on independent effects of beneficiary characteristics will inform design of adherence-based quality measures, while results on regional influences will help to explain geographic variations in medication use beyond differences in population health.   

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