A novel report explores the possible relationship between fluctuations in the stock market and the incidence of local heart attacks. The results were presented at the annual scientific meeting of the American College of Cardiology by a team of researchers from Duke University Medical Center.

The initial data analysis showed an increased incidence of heart attacks from the Duke Databank for Cardiovascular Disease from January 2008 to July 2009. After conducting a comprehensive analysis looking specifically at the relationship with the stock market during that time, there was a trend between increased heart attacks with stock market declines. However, when results were adjusted to account for a known seasonal increase in heart attacks during winter months, the relationship was less clear.

"In the unadjusted findings we saw a strong trend," says Christopher O'Connor MD, Director of the Duke Heart Center and senior author of the paper. "However, previous studies have not done these analyses with a seasonal correction. Previous research has shown that myocardial infarctions (MIs) occur more frequently during winter months than summer months. When we corrected for seasonality, we learned the time of year could be impacting our results."

After the U.S. suffered a severe economic crisis in the fall of 2008, the Duke researchers designed a pilot, single site observational study to explore whether the economic crisis and stock market volatility impacted cardiovascular (CV) event rates. Few studies have explored how economic trends impact cardiovascular events, explains Mona Fiuzat, PharmD, a researcher at Duke and the study's lead investigator.

During preliminary analysis, when the data were plotted against the daily NASDAQ opening values during the decline period, it revealed an inverse relationship between heart attacks and stock markets. "You can see the visual pattern," says Fiuzat. "During the period that the NASDAQ was declining, the MI rates were increasing."

However, when more rigorous testing was used to specifically test the correlation with stock market values and eliminate the seasonable variability, the research question could no longer be answered. "The stock market declined during the winter, and previous studies show more MIs occur during the winter," says Fiuzat. "Therefore, we can't say definitively that there is an association. There is the possibility that there is no relationship."

Fiuzat and O'Connor say the study had other limitations, including its sample size, its regional bias, and the large variability of MI events within the Duke database. They plan to conduct a larger study, over a longer period of time, to determine whether a relationship between the stock market and heart attack rates exists.