Elsevier

American Heart Journal

Volume 156, Issue 3, September 2008, Pages 483-490
American Heart Journal

Clinical Investigation
Outcomes, Health Policy, and Managed Care
Disparities in myocardial infarction case fatality rates among the elderly: The 20-year Medicare experience

https://doi.org/10.1016/j.ahj.2008.04.009Get rights and content

Background

Case fatality rates after acute myocardial infarction (MI) have decreased markedly over the last 3 decades. Some subgroups may have benefited more than others, but this hypothesis has not been evaluated in a large nationally representative cohort. Accordingly, we sought to assess long-term temporal trends in mortality after hospitalization for MI and to assess whether these trends differ by sex, race, or age in a cohort of elderly patients.

Methods

We studied a cohort of 4.9 million Medicare beneficiaries ≥65 years hospitalized for MI between 1984 and 2003 and calculated the proportion that died inhospital, within 30 days, and within 1 year of hospitalization. We used multivariable risk models to estimate relative and absolute changes in case fatality rate according to race, sex, and age groups.

Results

After adjustment for age, sex, and race, between 1984 and 2003, there was a 54.3% (95% CI 53.7%-54.8%), 39.7% (95% CI 39.1%-40.3%), and 23.0% (95% CI 22.5%-23.5%) reduction in the risk of inhospital, 30-day, and 1-year mortality, respectively. Relative and absolute reductions were greater in whites than in blacks, with the biggest differences observed for 1-year mortality. Small and inconsistent differences were seen by sex after stratifying by race. Patients aged ≥90 years experienced the smallest relative reductions in case fatality rates, with the biggest differences observed for 1-year mortality.

Conclusions

Among US Medicare beneficiaries, short-term MI case fatality rates have decreased significantly in all groups, but more so among whites than blacks. Additional studies are needed to clarify the basis for these observations.

Section snippets

Methods

Medicare is a US federal health insurance program that reimburses in-patient costs for most citizens and permanent residents aged ≥65 years. We obtained administrative data for all claims submitted to the Centers for Medicare and Medicaid Services by US short-stay hospitals for services provided to Medicare beneficiaries. For each hospitalization, we obtained data on age, sex, race, admission date, discharge date, length of stay, date of death, principal discharge diagnosis (coded according to

Results

Between 1984 and 2003, there were >6.8 million hospitalizations in the United States with a principle discharge diagnosis of MI among Medicare beneficiaries aged ≥65 years. After excluding cases with race other than white or black, accounting for duplicate records, and accounting for hospital transfers, 5.9 million hospitalizations among 4.9 million unique individuals were available for analysis. Most patients (84.1%) were hospitalized for MI only once during the observation period. Among the

Discussion

In this nationally representative cohort of elderly patients, we found that inhospital and short-term mortality after MI decreased dramatically over the 20-year period between 1984 and 2003, overall and within subgroups defined by race, sex, and age. However, the magnitude of this improvement varied significantly between subgroups.

Several,2, 15, 16 but not all,3, 17 national and community-based studies have previously shown that inhospital mortality after MI has improved over time. NRMI—the

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    The project described was supported by grants F32-ES013804 and K99-ES015774 from the National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health (NIH), and R827353 from the US Environmental Protection Agency (EPA). Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the NIEHS, NIH, or EPA.

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