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EDITORIALS |
From the Department of Medicine, Division of Cardiovascular Medicine, University of Florida, and the Malcom Randall VA Medical Center, Gainesville, Florida (D.S.S.); Department of Psychiatry and School of Nursing, McGill University, Montreal Heart Institute Research Center, Centre Hospitalier de l’Université deMontréal, Montreal, Quebec, Canada (N.F.-S.); Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri (K.E.F., R.M.C.).
Address correspondence and reprint requests to David S. Sheps, MD, MSPH, Department of Medicine, Division of Cardiovascular Medicine, University of Florida, Malcom Randall VA Medical Center, Gainesville, Florida. E-mail: shepsds{at}medicine.ufl.edu
INTRODUCTION
We seldom write editorials about publications in other journals, but this is an unusual situation. The Lancet recently published two important papers on the INTERHEART study of risk factors for myocardial infarction (MI) (1,2). These are landmark papers that should be of particular interest to our readership because they underscore the role of biobehavioral contributions to health status.
INTERHEART was a standardized case-control study of acute myocardial infarction conducted in 52 countries. It included 15,152 cases and 14,820 controls. The study was designed to examine the relationship of smoking, history of hypertension or diabetes, waist-hip ratio, dietary patterns, physical activity, consumption of alcohol, blood apolipoproteins and psychosocial factors to myocardial infarction. Not surprisingly, smoking, raised apo-B apo-A1 ratio, history of hypertension, diabetes, and abdominal obesity were significantly more common among cases (of acute MI) than among controls (who had no previous diagnosis of heart disease or history of exertional chest pain). Other potentially alterable behavioral factors, including diet and physical activity, and alcohol consumption (with a protective effect from moderate consumption), also emerged as significant contributors to the level of risk. However, psychosocial risk factors, including stress, depression and low generalized locus of control, were also more common among cases and were responsible for 32.5% of the population attributable risk for MI. This is independent of, and only slightly less than, the population attributable risk for lifetime smoking (35.7%), and greater than that for hypertension (17.9%) or obesity (20.0%). The population attributable risk is based on both the prevalence of a risk factor, and the size of the increase in risk, and estimates the reduction in MI incidence that would occur if the risk factor were to be eliminated. These associations were noted in men and women across all age groups and in all regions of the world. Also, importantly and interestingly, these nine risk factors accounted for 90% of the population attributable risk in men and 95% in women.
INTERHEART is a tremendously important study for a variety of reasons. Much of our previous information about risk factors was derived from developed countries. This study, in contrast, was performed in 52 countries representing every inhabited continent. In addition, unlike many previous studies, it had an adequate sample of women, and the researchers assessed several different psychosocial risks using a series of questions selected from previous predictive studies of cardiovascular events. Although the measures used do not represent the state of the art of psychosocial measurement, the size of the sample, its international content, and the magnitude and prevalences of the observed risks make the psychosocial findings the most exciting part of this study for readers of Psychosomatic Medicine.
Psychosocial stress during the previous 12 months was assessed with three single-item questions about financial stress, stress at work and stress at home. In these questions stress was defined as feeling irritable or anxious, or as having disturbed sleep. Participants were also asked to indicate which, if any, of nine stressful events had occurred in the previous 12 months. Generalized locus of control was assessed using six questions concerning perceived control over life circumstances and positive expectations for the future. For depression, subjects were asked if there was ever a time in the past 12 months that they had "felt sad, blue or depressed for two or more weeks in a row," and, if so, were asked about the symptoms of loss of interest, tiredness, weight changes, sleep difficulties, troubles concentrating, thoughts of death, and worthlessness. Compared with controls, cases reported more frequent periods of stress at home during the previous 12 months as well as more frequent periods of stress at work. They were also more likely to report 2 weeks or more of feeling depressed. In contrast, high locus of control was a significant protective factor. Combining any exposure to general stress, financial stress, stressful life events, depression and low locus of control, a population attributable risk of 29% was estimated after adjustment for age, sex, geographic region, and smoking. Further adjustment for all other risk factors changed this risk estimate to 32.5%.
Of course the study findings do have several limitations as acknowledged by the authors. Most importantly, cases were interviewed during hospitalization following an acute MI and were asked to report on psychosocial risks during the 12 months before the event. Current feelings of stress and depression accompanying the MI could have biased the accuracy of these reports. Errors in measurement for all risk factors and potential case-control differences in accuracy of some of the assessments also cannot be ruled out. Finally, estimates of prevalences for risk factors were based on hospitalized individuals and controls, and therefore may not represent population prevalences for all countries evaluated.
The authors’ conclusions are worthy of note. They state that "if this effect (of psychosocial stress) is truly causal, the importance of psychosocial factors is much more important than commonly recognized, and might contribute to a substantial proportion of acute myocardial infarction."
This conclusion is all the more important to those of us who are researchers or clinicians in the interdisciplinary field of behavioral medicine because it was published in a general medical journal, and in a journal whose research is cited at one of the world’s highest rates. We believe that this study will inspire much more research in these areas, that it will contribute to an aura of legitimacy for behavioral research studies and that it will make it easier for future behavioral research to reach a wider medical audience. The publication of these studies should encourage our colleagues to move forward in these areas and not be discouraged as some were after the publication of the results from the ENRICHD trial (3). In combination with the psychosocial risks including depression and stress, the role of potentially alterable behavioral risks (smoking, diet, exercise, alcohol) in the development of cardiac disease is overwhelming. These results provide a major opportunity for members of the American Psychosomatic Society (APS) to become further involved in disease prevention and the integration of behavioral approaches and concepts within general practice medicine.
The APS has been actively working to raise awareness of the importance of behavioral risk factors in the general medicine community. In addition, Psychosomatic Medicine will soon be publishing a supplement on the co-morbidity of depression and cardiovascular disease. The publication of the landmark INTERHEART study by the Lancet is evidence that psychosocial factors are important to the mainstream medical community. We believe that this can only increase the interest of the general medical community in the type of work we do. It is our goal to continue to promote and publish high quality research that has broad clinical importance. We hope that the general medical community will grow to appreciate what has been known by members of this society for many years—that biobehavioral factors play important roles in health and illness, and must therefore play an equally important role in medical research.
REFERENCES
This article has been cited by other articles:
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  E. P. Vamos, I. Mucsi, A. Keszei, M. S. Kopp, and M. Novak Comorbid Depression Is Associated With Increased Healthcare Utilization and Lost Productivity in Persons With Diabetes: A Large Nationally Representative Hungarian Population Survey Psychosom Med, June 1, 2009; 71(5): 501 - 507. [Abstract] [Full Text] [PDF]
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K. E. Freedland, G. E. Miller, and D. S. Sheps The Great Debate, revisited. Psychosom Med, March 1, 2006; 68(2): 179 - 184. [Full Text] [PDF]
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 T. R. Insel and R. Quirion Psychiatry as a Clinical Neuroscience Discipline JAMA, November 2, 2005; 294(17): 2221 - 2224. [Full Text] [PDF]
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R. M. Carney, K. E. Freedland, and D. S. Sheps Depression is a Risk Factor for Mortality in Coronary Heart Disease Psychosom Med, November 1, 2004; 66(6): 799 - 801. [Full Text] [PDF]
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