Recurrent Acute MI Hospitalizations among Medicare Beneficiaries

In a national sample of Medicare beneficiaries, a study found that the rate of recurrent hospitalizations for acute myocardial infarction (MI) has decreased in recent years, according to a recent study [J Am Heart Assoc. 2014;3:e001197].

Though studies have indicated a decline in hospitalizations and deaths due to acute MI, few studies have examined recurrent hospitalizations for acute MI. In the current study, researchers sought to fill this void and understand the occurrence and outcomes of recurrent hospitalizations.

The study included 2,305,441 Medicare beneficiaries; inpatient data were obtained from the Medicare Provider Analysis and Review, which was provided by the Centers for Medicare & Medicaid Services. The researchers identified a complete sample of fee-for-service Medicare beneficiaries who were hospitalized for acute MI between January 1, 1999, and December 31, 2011.

Study participants were included if they were ≥65 years of age and discharged alive from an acute care hospital with a principal discharge diagnosis of acute MI, per the International Classification of Diseases, 9th Revision. The first admission for acute MI was the “index acute MI” and the second hospitalization was classified as the “recurrent acute MI hospitalization.” Patients with a total hospital length of stay ≤1 day were
excluded from the study.

The mean age of the study participants was 78.8 years, 50.4% were women, and 12% were of nonwhite race. The most common baseline comorbidities were coronary artery disease (72.5%), hypertension (60.2%), diabetes (31.4%), chronic obstructive pulmonary disease (23.2%), and heart failure (15.9%).

The primary study end point was recurrent acute MI within 1 year of admission for the index acute MI. The secondary end point was 1-year all-cause mortality rates among patients who were hospitalized for recurrent acute MI.

The researchers found that during the 12-year study period, the observed recurrent acute MI hospitalization rate declined from 12.1% in 1999 (95% confidence interval [CI], 11.9-12.9) to 8.9% in 2010 (95% CI, 8.8-9.1), amounting to a relative decline of 26.4%.

The observed recurrent acute MI hospitalization rate declined by a relative 27.7% in white patients from 11.9% (95% CI, 11.8-12.1) to 8.6% (95% CI, 8.5-8.8) compared with a relative decline in black patients of 13.6% from 13.2% (95% CI, 12.6-13.8) to 11.4% (95% CI, 10.9-12).

The risk-adjusted rate of annual decline in recurrent acute MI hospitalizations was 4.1% (hazard ratio [HR], 0.959; 95% CI, 0.958-0.961), and white patients experienced a higher rate of decline (HR, 0.979; 95% CI, 0.956-0.959) compared with black patients (HR, 0.974; 95% CI, 0.97-0.979).

The researchers saw an overall observed 1-year mortality rate after hospitalization for recurrent acute MI decline from 32.5% in 1999 to 29.7% in 2010, a relative decline of 8.3% (P<.05). The 1-year mortality after recurrent acute MI hospitalization declined 1.8% per year in an adjusted analysis (HR, 0.982; 95% CI, 0.98-0.985).

The study’s authors indicated limitations, including that data were based on a Medicare fee-for-service population, so trends may differ among other patient populations or among those with different health insurance providers. In addition, comorbidities were obtained from administrative codes and not clinically confirmed.

The researchers suggested that further studies be conducted to examine strategies to ensure that gains realized in post-acute MI outcomes can be shared equally among all patients.—Kerri Fitzgerald