By Blair Ford Mohney and Sarah Grace

In the last post, we highlighted trends in the migration of beneficiaries between Medicare fee-for-service and Medicare Advantage in the United States. In doing so, we can understand why this is such a hot topic for so many of our members across various markets. We are regularly asked: What can we learn about Medicare Advantage populations based on the fee-for-service data? How can we use it to reach more patients and improve their health outcomes?

At CareJourney, we pride ourselves on making data actionable. Medicare Advantage “switchers” data is no anomaly. As described in part one of this series, the actionable opportunities we see for this data include improving plan selection and patient care. Yet, as the industry is well aware, Medicare Advantage data is rare, inconsistent, and not standardized. This presents a challenge for data access and interpretation. So, what is an organization to do?

CareJourney’s main source of data is fee-for-service (FFS) Medicare claims. We believe that these are a good proxy to understand Medicare Advantage populations and the care they receive. Some people may question whether this data is a relevant apples-to-apples comparison. By focusing on the population of beneficiaries switching from fee-for-service to Medicare Advantage who have been in both populations, we can begin to answer this question.

Who exactly are Medicare Advantage “switchers”?

While the answer is complex and situationally dependant, we can look at this question from three different vantage points.


As a reminder, this analysis is based on paired year-over-year enrollment data between 2013-2018. In the “base” year, beneficiaries are classified based on a full year of enrollment in either traditional fee-for-service or Medicare Advantage. In the following year, beneficiaries are grouped based on whether they continued in their current enrollment for the full year, switched enrollments for the full year, or neither (beneficiaries who died or switched enrollment mid-year are in this group).

Leveraging demographic data for all enrollees, and claims data for fee-for-service enrollees, we can understand the differences in chronic condition prevalence and other personal characteristics between fee-for-service to Medicare Advantage “switchers” and fee-for-service “stayers”.

Do beneficiaries switch to Medicare Advantage at higher rates when they are first eligible?

It is reasonable to wonder if the “switchers” population predominantly consists of individuals newly eligible for Medicare. If this were the case, it would imply that this is an inherently different population than the individuals in the historical fee-for-service claims.

The data suggests that this is not the case. Among brand new Medicare-eligible patients, about 28% enrolled straight into a Medicare Advantage plan. Looking further, about another 4% switched into Medicare Advantage from fee-for-service after one year of Medicare eligibility. In total, this yields about a 32% Medicare Advantage penetration rate among these newly eligible beneficiaries. In comparing this to the overall percentage of Medicare patients who are enrolled in a Medicare Advantage plan (not solely those newly eligible), we see comparable proportions.

Additionally, while this 32% of newly eligible Medicare patients enrolling straight into a Medicare Advantage plan might seem high, these newly eligible “switchers” only represent about 1% of all beneficiaries switching into Medicare Advantage in any given year.

The main takeaway here is that patients are switching into Medicare Advantage across all points of their Medicare journey and not just when they are new to Medicare (as noted below, the average age of “switchers” is about 71). As a result, a lot of the patients were enrolled in fee-for-service at one point in time and we have historical claims outlining their patient history.

Are Medicare Advantage “switchers” different in age and risk from fee-for-service “stayers”?

In the chart below, we are able to see the average age and the Hierarchical Condition Category (HCC) risk scores for patients. These patients are broken down into two cohorts:

  1. Stay – those who are enrolled in fee-for-service (FFS) in the base year, and remain in FFS in the subsequent year (the year noted)
  2. Switch – those who are enrolled in FFS in the base year, and switch into a Medicare Advantage plan in the subsequent year (the year noted)
Weighted Average Age Weighted Average HCC Score
Stay 71.48 1.11
Switch 70.97 0.88
Stay 71.49 1.10
Switch 70.08 0.91
Stay 71.53 1.10
Switch 70.08 0.90
Stay 71.60 1.12
Switch 71.93 0.98
Stay 71.68 1.15
Switch 71.01 1.01

From our perspective, there is not much of a difference between these two cohorts. In terms of age, both populations are about 71 on average. We similarly do not see a substantial difference in the riskiness of the two cohorts.

Furthermore, across this longitudinal view spanning five years, we see a relatively consistent pattern. Therefore, from an age and HCC risk score perspective, we have reason to believe that the Medicare Advantage “switchers” and “stayers” are again comparable populations.

Do Medicare Advantage “switchers” struggle with different chronic conditions?

A third way in which Medicare Advantage switchers might be different from the broader fee-for-service population is with regard to their specific chronic conditions.

To begin to answer this question, we broke out prevalence rates for a selection of the most prevalent chronic conditions among those that stayed in fee-for-service Medicare, and those that switched to Medicare Advantage. These rates are displayed for 2014-2018 in the table below.

HCC Code Description 2014 2015 2016 2017 2018
HCC 18 Diabetes with Chronic Complications
Stay in FFS 9.97% 10.08% 10.15% 12.48% 15.25%
Switch from FFS to MA 8.37% 8.88% 8.90% 12.26% 15.49%
HCC 19 Diabetes without Complication
Stay in FFS 17.49% 17.15% 16.85% 13.09% 11.39%
Switch from FFS to MA 17.67% 16.93% 16.62% 13.49% 11.76%
HCC 85 Congestive Heart Failure
Stay in FFS 11.51% 11.27% 11.03% 11.10% 10.99%
Switch from FFS to MA 7.95% 8.03% 7.71% 9.18% 9.04%
HCC 96 Specified Heart Arrhythmias
Stay in FFS 12.65% 12.69% 12.71% 12.52% 12.90%
Switch from FFS to MA 9.35% 9.01% 8.84% 11.09% 10.38%
HCC 108 Vascular Disease
Stay in FFS 13.40% 13.31% 13.21% 13.37% 14.05%
Switch from FFS to MA 9.64% 10.02% 9.43% 11.65% 11.53%
HCC 111 Chronic Obstructive Pulmonary Disease
Stay in FFS 13.94% 13.65% 13.28% 12.13% 12.80%
Switch from FFS to MA 10.87% 10.99% 11.04% 10.35% 12.03%

While initial differences exist in the prevalence rates of Congestive Heart Failure,  specified heart arrhythmias, vascular disease, and Chronic Obstructive Pulmonary Disease among “switchers” and “stayers”, the gaps between these rates become smaller over time. At the same time, prevalence rates for diabetes (both with and without complication) are very similar. Overall, this suggests that the prevalence of the most common chronic conditions may not be that different between these two populations, and that they’re becoming more similar over time.

Another way to illustrate patterns in chronic conditions among “switchers” is by comparing 2014 fee-for-service HCC data with 2015 Medicare Advantage encounters data, allowing us to measure the impact of a chart review on HCC scores. The impacts are shown in the table below.

MA “Switchers”
HCC Prevalence Rates, 2014 – 2015 2014 FFS HCCs 2015 HCCs Including Chart Review 2015 HCCs Excluding Chart Review
Avg. HCC Score 0.97 1.09 1.04
Vascular Heirarchy HCC 107 (Vascular Disease with Complications) 1.36% 1.41% 1.36%
HCC 108 (Vascular Disease) 11.05% 13.82% 12.62%
Kidney Heirarchy HCC 134 (Dialysis Status) 0.01% 0.01% 0.00%
HCC 135 (Acute Renal Failure) 2.41% 2.83% 2.76%
HCC 136 (CKD, Stage 5) 0.16% 0.16% 0.15%
HCC 137 (CKD, Stage 4) 0.26% 0.38% 0.36%
Diabetes Heirarchy HCC 17 (Diabetes with Acute Complications) 0.19% 0.18% 0.17%
HCC 18 (Diabetes with Chronic Complications) 9.74% 13.13% 12.36%
HCC 19 (Diabetes Without Complication) 17.72% 14.55% 14.61%
HCC 22 (Morbid Obesity) 3.33% 6.42% 4.67%
Substance Abuse Heirarchy HCC 54 (Drug/Alcohol Psychosis) 0.25% 0.21% 0.20%
HCC 55 (Drug/Alcohol Dependence) 1.22% 1.94% 1.74%
HCC 84 (Cardiorespiratory Failure and Shock) 1.54% 1.89% 1.84%
HCC 85 (Congestive Heart Failure) 8.83% 10.67% 9.67%
Cardiac Arrest Heirarchy HCC 86 (Acute Myocardial Infarction) 0.48% 0.57% 0.56%
HCC 87 (Unstable Angina and Other Acute Ischemic Heart Disease) 1.20% 1.06% 1.02%
HCC 88 (Angina Pectoris) 1.43% 2.16% 1.87%
HCC 96 (Speciifed Heart Arrhythmias) 10.09% 11.07% 10.67%

While many common chronic conditions seem to be correctly coded for these patients while enrolled in traditional fee-for-service Medicare, some prevalence rates increased after a Medicare Advantage chart review, specifically for morbid obesity, CHF, and vascular disease. It also appears that many patients moved from a diagnosis of diabetes without complication to diabetes with complication post-chart review.

So, are Medicare Advantage “switchers” different from “stayers”?

While you were probably hoping for a concrete “yes” or “no” answer, the situation is still grey, as there would be many more ways to compare and contrast these populations (many more than can be included in a blog post!).

However, the main conclusion is that in some cases, the population of patients switching from fee-for-service to Medicare Advantage is not significantly different from the broader fee-for-service population. Therefore, there are a lot of fee-for-service insights we can apply to the Medicare Advantage population for improving plan selection and patient care. To garner these insights, it is important to dive into specific instances, cohorts of patients, and conditions.

Interested in seeing more?

If you are interested in learning more, we’d love to talk to you about the comparisons we can make for your specific population with our fee-for-service data set and growing Medicare Advantage data set. Reach out to your Member Services representative or contact us at [email protected].