A paper, "Association of Episodic Physical and Sexual Activity With Triggering of Acute Cardiac Events," published in the March 23/30 issue of the Journal of the American Medical Association (JAMA), highlights research done by Tufts Clinical and Translational Science Institute (CTSI) researchers Jessica K. Paulus, ScD, and Issa J. Dahabreh, MD. This paper was also developed into a JAMA Report video, available on the Tufts CTSI website. Broadcast formats are available at www.thejamareport.com.

The significance of this paper is that it summarizes a body of research that has spanned more than two decades and allows the synthesis of evidence from all available studies and the identification of patterns not discernible by looking at each study individually. This research is of broad interest to the general public since physical and sexual activity are common behaviors that affect a wide segment of the population. It's particularly important to clinicians since the study supports current clinical guidelines regarding the initiation of physical activity programs.

The JAMA paper assesses the effect of episodic physical and sexual activity on acute cardiac events using data from fourteen previously published studies. Acute cardiac events are defined in this study as myocardial infarction or sudden cardiac death. Acute cardiac events are a major cause of morbidity and mortality, with as many as one million myocardial infarctions and 300,000 cardiac arrests occurring in the United States each year. Despite the well-established benefits of regular physical activity, anecdotal evidence has suggested that physical activity and psychological stress can act as triggers of acute cardiac events.

The authors conducted a meta-analysis of fourteen case-crossover studies published in thirteen articles; ten studies investigated physical activity, three studies investigated sexual activity, and one study investigated both exposures. Since many prior reports included a relatively small number of individuals who had had heart attacks, they used a statistical approach that combined the data from these previous studies. "This method can be a powerful way to arrive at a more confident answer about a particular clinical question when prior studies have been limited by small numbers," writes Dr. Paulus.

Each author independently extracted descriptive and quantitative information from the studies identified through MEDLINE, EMBASE and Web of Science. Data collection was limited to case-crossover studies as this design was developed specifically to address the problem of identifying triggers of acute events. Case-control and cohort studies were not included as they are not particularly suitable for identifying triggers of acute events. The individual studies tended to include more males than females, and patients in their 50's and 60's.

This research concluded that episodic physical activity and sexual activity are associated with an increase in the risk of heart attacks for a short window of time during and shortly after the activity. This association was less pronounced among persons with high levels of habitual physical activity. The authors make particular note that this study should not de-emphasize the importance of regular physical activity. Dr. Dahabreh writes, "Our findings should not be misinterpreted as indicating a net harm of physical or sexual activity; instead they demonstrate that these exposures are associated with a temporary short-term increase in the risk of acute cardiac events."

Dr. Paulus comments, "This project would not have been possible without the Tufts CTSI funded Clinical and Translational Science Graduate Program, as well as Tufts CTSI support for interaction between epidemiologists and meta-analysis experts. While our disciplines are not necessarily that far apart, our scientific approaches tend to keep us operating in different spheres. This work is an illustration of what is possible with Tufts CTSI encouragement and support for these types of interactions."