Have Star Ratings improved medication adherence?

Each year, the Centers for Medicare and Medicaid Services (CMS) collect various quality and performance measures on Medicare Advantage (MA) plans. CMS analyzes this massive collection of information and assigns from 1 star to 5 stars to each plan, where 5 stars represent excellent performance.

There are huge financial incentives for receiving 5 stars. On top of the prestige of being a 5 star plan, these plans receive 5% bonus as well as extended enrollment periods. On the other hand, if a plan receives 2 stars or below for three years in a row, the plan will be terminated by CMS.

For this reason, almost every plan is desperate to get higher stars in this grading system. Many plans have adopted population health software, patient engagement solutions, and provider education approaches. It is apparent that this rating system has drastically changed how MA plans operate. However, has this rating system changed the quality of care to the members of MA plans? Let’s find out.

Here, I have picked three medication adherence measures: diabetes, hypertension, and cholesterol medication adherence scores measured by Proportion of Days Covered. In order to manage chronic conditions, members need to take medications as directed. These measures are heavily weighted components in the overall Star Rating calculation.

Let’s see how these measures have affected MA plans and their members. The first chart shows yearly median adherence scores from all the MA plans in the nation.

As can be seen, the scores are smoothly rising, meaning that more and more patients are becoming adherent to these types of prescriptions.* To have a bit more comprehensive view on what’s really going on, I have prepared another plot.

This chart shows yearly standard deviations. It is obvious that the standard deviations are going down. This means that the difference between plans has been shrinking. In other words, the improvement over time is not driven by one or two plans, but by all plans together.

To summarize, after the medication adherence measures have been added to the Star Rating system,

• the overall adherence has been increasing (from the first chart)
• this improvement is happening across many MA plans (from the second chart)

The Star Rating has been working as it was originally intended (at least on some measures). Of course, the ultimate test is whether or not these measures have the expected effect on outcomes, but that’s a topic for another post.

— -

Footnote:

*as measured by PDC; the multifaceted issue of medication adherence is beyond the scope of this post