Prime Insights

Can big data help boost medicine-related Star ratings? 

Patrick Gleason, PharmD, FCCP, BCPS | Aug. 24, 2016


Improving adherence starts with understanding what influences it.  Better yet, understanding what factors and behaviors can predict it, and promoting them. Proactively improving adherence means better outcomes and healthier members. And healthier members mean lower health care costs. Everyone wins.

For Medicare plan sponsors, improved adherence also means higher Star ratings. For Part D plan sponsors, adherence for the three related drug categories accounts for 28 percent of Star ratings. These measures can make or break a plan’s chance for a sizable 5 percent per member per month (PMPM) reimbursement bonus from the Centers for Medicare and Medicaid Services (CMS).

Who and what we studied
To better understand what factors may predict adherence, my team studied data from 1.1 million Medicare members over three years. Using claims data, census data, pharmacy risk group score (measuring illness severity), benefit design data, and enrollment data, we:

  • Studied more than 80 potential adherence predictors for the three CMS adherence drug categories: renin angiotensin system (RAS) antagonists for high blood pressure, cholesterol-lowering statins and medicines for diabetes (excluding insulin)
  • Tested the accuracy of our predictive modeling
  • Identified which factors can be influenced through pharmacy benefit management strategies

The top predictors of adherence
Our research found individual characteristics and behaviors that predicted adherence in all three drug categories. Not surprisingly, the most important predictor of future adherence was past adherence. Members who had been adherent in the past year (i.e., that had a weighted 30-day equivalent claim count of seven or more within the category) were three times or more likely to be adherent to drugs in these categories.*

Individual characteristics also predicted adherence. Although they can’t be modified, these attributes can be useful in understanding the likelihood of adherence for a specific population and when to target members for interventions. Some of the top characteristic predictors include:

  • Percent of high school graduates in an individual’s zip code
  • Median income in an individual’s zip code
  • Enrollment in a Medicare Advantage plan
  • Non-low income status subsidy in the previous year
  • Younger age

Use of two benefit design features in the previous year consistently predicted adherence in all three categories:

  • Having a mail-order or retail 90-day supply claim in the category increased the odds of adherence by 24–33 percent
  • Having a generic cost share of $1–$4 or less per 30-day supply in the drug category  ncreased the odds of adherence 20–25 percent

To improve adherence, Prime strongly recommends designing benefit plans to have a $4 generic cost share for 30-day supplies of drugs in Star-related categories, as well as incenting members to fill 90-day supplies.

Our research identified many other interesting predictors that plan sponsors should considering in targeting members for adherence interventions. Stay tuned for my next post, which will further explore how predictors varied by CMS drug adherence category. If you’d like to learn more, please contact us.

*Prior year statin adherence was found to be a predictor of RAS antagonist adherence.


About Prime Therapeutics

Prime Therapeutics LLC (Prime) helps people get the medicine they need to feel better and live well. Prime manages pharmacy benefits for health plans, employers, and government programs including Medicare and Medicaid. The company processes claims and delivers medicine to members, offering clinical services for people with complex medical conditions. Headquartered in St. Paul, Minn., Prime serves just over 22 million people. It is collectively owned by 14 Blue Cross and Blue Shield Plans, subsidiaries or affiliates of those plans. Prime has been recognized as one of the fastest-growing private companies in the nation.  

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