Reductions in Acute MI Hospitalization, Mortality Seen Across Income Levels, but Disparities Linger

Over the past 15 years or so, hospitalizations and deaths related to acute MI have fallen across the United States, with counties at all levels of median income reaping the benefits, a new study of Medicare beneficiaries shows.

Low-income counties, however, continue to have hospitalization rates that are about 25% higher than those seen in the wealthiest areas.

The study, which was published online May 11, 2016, ahead of print in JAMA Cardiology, shows continuing disparities despite some progress, according to lead author Erica Spatz, MD (Yale University, New Haven, CT).

“We need to take a deeper look into the communities that are lagging behind and understand the contextual factors that contribute to higher disease rates,” she told TCTMD in an email. “Then, we need to really invest big in these communities. Our study highlights that more targeted efforts, especially in pockets like the Southeast, need to be the focus of future campaigns to promote cardiovascular health.”

Although it’s been known that acute MI and resulting mortality rates have declined in recent years, it was not known whether those improvements were felt across communities at different economic levels. Low-income areas, for instance, often face barriers to improving cardiovascular health, including an inadequate supply of physicians, poor quality of care, and limited resources dedicated to prevention and management of cardiovascular disease.

“Also in these areas, exposure to stress, unemployment, and inadequate social support may attenuate the effects of efforts to improve cardiovascular health,” the authors note.

Lag of About 4 Years Observed

To explore potential disparities, the researchers looked at trends in acute MI hospitalization and mortality rates between 1999 and 2013 by US county-level income. They used Medicare data for roughly 60 million unique fee-for-service beneficiaries ages 65 years and older and determined the income level of the patients’ counties using 1999 US Census Bureau data adjusted for inflation. Three income levels were examined: low (< 25th percentile), average (25th to 75th percentile), and high (> 75th percentile).

During the study period, acute MI hospitalization and mortality rates fell for all three income groups. Risk-standardized mortality at 1 year declined from about 31% in 1999 to about 26% in 2013, with no differences by county-level income.

As for hospitalizations, the rate of decline over time was similar for all income groups, but the mean hospitalization rate was higher for low- vs high-income counties both in 1999 (1,353 vs 1,123 per 100,000 person-years) and in 2013 (853 vs 648 per 100,000 person-years). The investigators calculated that it would take an additional 4.3 years for low-income counties to match the rates seen in high-income counties.

Unique Challenges for Low-Income Areas

When explaining the persistent disparity in hospitalization rates, the authors say “high-income counties may have a greater capacity to quickly adopt new models of care delivery, join campaigns to reduce [acute MI], and implement evidence-based primary and secondary treatment recommendations.

“In addition, high-income communities may have greater resources to invest in the physical and social health environment,” they continue. “Conversely, low-income communities may face unique challenges (eg, closure of health centers during economic depression) or disorganized health services that could attenuate the success of new primary and secondary prevention efforts to reduce [acute MI].”

Spatz said the fact that mortality did not follow a similar pattern was surprising.

“One explanation may be that once a major event like a heart attack occurs, the environment, including healthcare and social supports, may be equally responsive across communities; that is to say that we do a better job with secondary prevention than with primary prevention in low-income communities,” she said. “Another explanation is that 1-year mortality is related to hospital quality, and that this may have been similar across the different income groups. Further studies are need, however, to understand the lack of difference.”

In an accompanying editorial, Karen Joynt, MD (Brigham and Women’s Hospital, Boston, MA), and Thomas Maddox, MD (Veterans Affairs Eastern Colorado Health Care System, Denver), say the finding that mortality rates have dropped across income groups “suggests that efforts to standardize and improve quality of care for [acute MI], both during the acute hospitalization for the event and after hospitalization, have had their intended effect.”

But they add that the consistently higher rate of hospitalization in low-income counties is concerning.

Even though the recent gains in mortality and hospitalization “should give us great pride, our work is not done,” Joynt and Maddox conclude. “Focusing our efforts on areas such as the quality of ambulatory care in primary and secondary prevention of [acute MI], as well as giving greater attention to the social determinants of health, may hold immense promise in addressing significant and persistent disparities in health and health outcomes for the nation’s most vulnerable populations.”

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