Care and Outcomes of Patients Hospitalized with Heart Attack in December

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The summary below is from the full report titled "Evidence-Based Therapies and Mortality in Patients Hospitalized in December with Acute Myocardial Infarction." It is in the 4 October 2005 issue of Annals of Internal Medicine (volume 143, pages 481-485). The authors are T.J. Meine, M.R. Patel, V. DePuy, L.H. Curtis, S.V. Rao, B.J. Gersh, K.A. Schulman, and J.G. Jollis.

What is the problem and what is known about it so far?

Acute myocardial infarction, more commonly known as heart attack, involves blockages in blood flow to heart muscle that cause a section of heart muscle to die. Fortunately, proven treatments improve the outcomes of people with heart attack. These treatments include medications such as aspirin or beta-blockers and procedures to open up the blocked blood vessels. Blocked blood vessels can be opened up by thrombolytic therapy or by percutaneous coronary interventions. During thrombolytic therapy, special medication is injected into the bloodstream to dissolve the blockages. Percutaneous coronary interventions are procedures where doctors thread special instruments through the blood vessels in the groin up to the heart to open up clots using balloons or expandable tubes called stents. Past studies suggest that people hospitalized with a heart attack in December have worse outcomes than people who have a heart attack during other months. A possible explanation for the worse outcomes in patients who have a heart attack in December could be that they are less likely to get recommended therapies during staffing disruptions that occur during the holiday season than during parts of the year when staffing is at usual levels.

Why did the researchers do this particular study?

To compare the care and outcomes of patients hospitalized with a heart attack in December and those hospitalized in other months.

Who was studied?

127,959 patients with Medicare insurance (the insurance program for Americans older than age 65 years) who were hospitalized with a heart attack between January 1994 and February 1996.

How was the study done?

The researchers compared the numbers of patients hospitalized in December and those hospitalized in other months who died within 30 days of hospital admission. They also compared the numbers of patients who received aspirin, beta-blockers, and thrombolytic therapy or percutaneous coronary intervention. All of these comparisons accounted for factors that could also explain differences in outcomes, such as age, patient level of illness, or hospital type.

What did the researchers find?

Approximately 22% of patients hospitalized in December died within 30 days compared with 20.1% of patients hospitalized in other months. This difference in death rates is larger than one would expect by chance alone. However, the use of proven therapies was similar in December and in other months.

What were the limitations of the study?

This study was unable to determine why patients hospitalized with a heart attack in December had worse outcomes than patients hospitalized with a heart attack during other months.

What are the implications of the study?

Decreased use of proven therapies does not seem to explain why patients who have heart attacks have higher death rates in December than in other months.