Lancet. 2004;364(9438):937-952.
Background
Current knowledge about coronary heart disease prevention is mainly derived from studies done in developed countries. However, taking into account population densities, about 80% of the cardiovascular disease burden now lies within low-income and middle-income countries. It is unclear as to what extent these established coronary risk factors can be extrapolated to other populations worldwide.
Objective
To clarify whether the effects of cardiovascular risk factors vary in different countries or ethnic groups.
Methods
INTERHEART is a large, international, case-control study designed to assess the importance of risk factors for coronary heart disease worldwide. In this study, participants who presented with an acute myocardial infarction (AMI) were recruited from 262 centers from 52 countries in Asia, Europe, the Middle East, Africa, Australia, North America, and South America. At least one age- and sex-matched control was recruited per case. Nine easily measured risk factors were determined, which included smoking, history of hypertension or diabetes, waist-hip ratio, dietary pattern, physical activity, alcohol consumption, blood apolipoproteins, and psychosocial factors. Odds ratios for the association of these risk factors to myocardial infarction were determined and their population-attributable risks (PAR) were calculated.
Results
A total of 12,461 cases and 14,637 controls were included in the analysis. The overall median age of cases with first AMI is about 9 years lower in men than in women in all regions of the world. All risk factors were significantly related to AMI except for alcohol consumption. Body-mass index (BMI) showed only a modest relation with AMI and was not significant when abdominal obesity (defined as waist-hip ratio) was included in the analysis. Daily consumption of fruits or vegetables, moderate or strenuous physical exercise, and consumption of alcohol (>=3 times per week) were protective. Collectively, all 9 risk factors accounted for 90% of the PAR for AMI in men and 94% in women. The relative importance of every risk factor varied across different geographic regions, and was largely related to its prevalence.
Conclusions
This study showed that 9 easily measured and potentially modifiable risk factors accounted for more than 90% of the proportion of the risk of an AMI. The effect of these risk factors is consistent in men and women, across different geographic regions, and by ethnic group. Worldwide, the 2 most important cardiovascular risk factors are smoking and abnormal lipids. Psychosocial factors, abdominal obesity, diabetes, and hypertension were the next most important risk factors but their relative effect varied in different regions of the world. Hence, the overall approach to prevention of coronary heart disease could be similar worldwide, but with varying emphasis in different subgroups. Smoking avoidance, increased consumption of fruits and vegetables, and moderate activity should remain the cornerstone of coronary heart disease prevention in all populations.
Comments
This is one of the largest ethnically diverse studies to evaluate coronary risk factors, with at least 800 cases of AMI within every major ethnic group studied. It is disturbing to note that smoking emerges as 1 of the 2 most important risk factors worldwide. In low-income and middle-income countries, tobacco companies often have unfettered access to the population, specifically targeting the young. To achieve "Healthy People 2010," we need to recognize the global nature of the cardiovascular epidemic and turn our efforts to primary or even primordial coronary disease prevention in these communities.