Shifting Acute MI Outcomes by Medicare Type: A Window Into Insurer’s Influence

Older Americans with acute MI enrolled in Medicare Advantage (MA) plans in 2009 had similar or modestly better short-term mortality compared with those in traditional Medicare, with evidence of less resource utilization while hospitalized and after discharge, an analysis of US data suggest. By 2018, the gap in survival had narrowed but some differences remained.

The shifts over time in both managed plans offer a chance to better understand the influence of insurance type in the United States, researchers say.

“Over the last 10 or more years, there's been a huge growth in Medicare Advantage enrollment to the point where, in the current year, just over 50% of people that are eligible to sign up for Medicare Advantage are enrolling in MA plans,” Bruce E. Landon, MD (Harvard Medical School, Boston, MA), the study’s lead author, told TCTMD.

Also known as Medicare part C, MA was launched in 2003 as an alternative to traditional Medicare that’s advertised as a way for US patients age ≥ 65 years to get additional health services for less out-of-pocket cost. Some MA plans offer a zero premium and coverage for things that Medicare does not, such as vision, hearing, and dental visits. However, MA plans tend to be more restrictive in terms of the providers that patients can see and may require prior authorization for medications or procedures. individuals can opt-in to MA when they initially sign up for Medicare, or can switch over during yearly open enrollment periods.

While prior studies comparing acute MI treatment patterns between traditional Medicare and MA beneficiaries have found few differences, questions remain about disparities in care and mortality in light of the unprecedented growth of the newer insurance option.

“Managed-care plans do have a lot of tools available to them for improving the efficiency of care and how patients are managed. So, we wanted to see to what extent patients, at least with this particular clinical condition as a starting point, were managed differently in Medicare Advantage and traditional Medicare,” Landon said.

The analysis, which spanned 2009 through 2018, found that both STEMI and NSTEMI patients had lower 30-day mortality rates at the beginning of the study period if they were on MA versus traditional Medicare. By 2018, the differences had dissipated, though MA patients did have higher likelihood of receiving and adhering to guideline-directed medications after discharge, less resource utilization and fewer repeat hospitalizations, and were more likely to be discharged home than to a postacute care facility.

“To the extent that MA plans have been able to work with hospitals and providers to do things that make delivering health care less expensive by not using postacute care as much, by not having as many readmissions, I think that's a positive thing for society, and that ultimately will be reflected in the premiums that go with Medicare Advantage plans to some extent,” Landon said.

Tracking Changes in MA Patients and Outcomes

For the study, Landon and colleagues analyzed data on more than 2.2 million acute MI patients (mean age 78 years for STEMI and 79 years for NSTEMI; 42% female). While the Medicare and MA patients were mostly well-matched at baseline, diabetes was more common among the MA group with STEMI both in 2009 and in 2018.

Even after adjustment for age and sex, enrollment in MA was associated with a lower rate of 30-day mortality for STEMI in 2009 (18.4% vs 20.7%) compared with traditional Medicare. The difference remained after further adjusting for race/ethnicity and factors related to Medicare eligibility. At the 2018 time point, mortality rates were lower than in 2009 for both the MA and traditional Medicare groups, with no significant difference (17.7% vs 17.8%). A similar pattern was seen in the NSTEMI patients.

Landon said it’s most likely that the early benefit attributed to MA may be explained by some unmeasured residual differences in health status that, as the MA population grew and came to more closely resemble the traditional Medicare population, had less impact on outcomes over time.

In 2009, PCI rates for STEMI were 62.7% in the MA group versus 59.6% in the traditional-Medicare group, with no differences seen in 2018. Rates of CABG decreased in the MA group over time but were not significantly different from the traditional Medicare group by 2018.

In terms of resource use, the MA group had less interhospital transfer in 2009 and in 2018 compared with traditional Medicare, as well as less ICU admission. Discharge home was 71% for the MA group with STEMI and 67.3% for the traditional Medicare group, a 3.7-percent gap that narrowed to 1.3% in 2018, when rates were 71.5% and 70.2%, respectively. No differences were seen in length of stay between plans at either time point. Adjusted readmission rates within 30 days of discharge were lower in the MA group in 2009 and 2018.

Looking at the NSTEMI group, PCI was more common in MA patients by 2018 than in the traditional Medicare group (69.1% vs 67.8%), with similar patterns of less resource utilization and fewer readmissions as the STEMI group.

In both time periods, MA patients with STEMI and NSTEMI had higher rates of filled prescriptions than those with traditional Medicare, but the gaps narrowed over time. Among those who filled a prescription, adherence was generally higher in the MA group than traditional Medicare throughout the study period, but the differences narrowed over time.

The number of hospitals with MA patients treated for STEMI or NSTEMI increased over the study period, resulting in less concentration of MA patients within certain centers in 2018 than in 2009.

Overpayment Worries and Plan Differences

MA is not without controversy, with a recent New York Times article noting ongoing concerns about inflated billing and missing documentation, as well as allegations of fraud against some of the private insurers within the plan.

In an accompanying editorial, David J. Meyers, PhD (Brown University School of Public Health, Providence, RI), and colleagues note that with MA set to become the dominant form of Medicare coverage in the future, it should be redesigned to reduce overpayments and deliver high-value care.

The variation within MA plans also deserves more attention, Meyers and colleagues write. “While most of the prior literature has made simple binary comparisons between enrollment in either Medicare Advantage or traditional Medicare, hundreds of different contracts and insurers administer Medicare Advantage, and there are thousands of plans that vary in benefit design, physician networks, care coordination, and business strategies,” they add. Leaving this aspect unaccounted for leaves open important gaps in understanding “how the successes of high-performing plans can be replicated in lower-performing ones and whether some types of plans are better equipped to address the challenges of certain enrollee groups.”

Landon told TCTMD that the point is well taken.

“There is a lot of heterogeneity among MA plans, so it’s true that you can’t look at it as a singular entity because it really isn’t,” he said. “More work needs to be done in the future to understand if there are certain health plans that actually do a better job than others. But obviously, anytime you get down to smaller sample sizes associated with a single health plan, you have problems with sample size and statistical issues.”

Meyers and colleagues also point out that since much of the growth in MA enrollment has occurred among racial and ethnic minority patients, another priority should be to get a better picture of the equity of care provided in MA plans compared with traditional Medicare.