Lifetime risk of developing coronary heart disease

Abstract

Authors' replySir—Gilbert Ross and Jeff Stier correctly point out that smoking is a major risk factor for coronary heart disease, as it is for other cardiovascular diseases. Numerous epidemiological studies, including the Framingham Heart Study, have indicated that smoking is associated with increased risk of coronary events in the short term and intermediate term. The effects of smoking, however, on lifetime risk of coronary heart disease are unpredictable. As we stated in the final paragraph of our article, the results of lifetime risk analyses stratified by risk factor status (eg, for smokers and nonsmokers) “are not predictable since characteristics, such as smoking, that modify the risk of coronary heart disease also modify the risk of death from competing causes”. Put simply, the increased competing risk of death from lung cancer, other cancers, and chronic lung diseases may result in a lower lifetime risk of coronary heart disease among smokers. This difficulty is likely to be less relevant to risk factors such as hypertension and dyslipidaemia, which do not cause as striking increases in risk of competing causes of death.Another complicating factor is that smoking status frequently changes during the lifetime of an individual. We are developing methodologies that should allow calculation of lifetime risk by risk factor strata, accounting for changes in the status of exposure to the risk factor.Undoubtedly, patients, clinicians, and public health programmes should continue and expand efforts to reduce the prevalence of smoking on a local, national, and global scale. In doing so, the immense population burden of smoking-related diseases will decrease. Paradoxically, the lifetime risk of coronary heart disease among former smokers might rise if fewer of them died from lung cancer and other causes, and they therefore lived on long enough to have a first coronary event. Authors' reply Sir—Gilbert Ross and Jeff Stier correctly point out that smoking is a major risk factor for coronary heart disease, as it is for other cardiovascular diseases. Numerous epidemiological studies, including the Framingham Heart Study, have indicated that smoking is associated with increased risk of coronary events in the short term and intermediate term. The effects of smoking, however, on lifetime risk of coronary heart disease are unpredictable. As we stated in the final paragraph of our article, the results of lifetime risk analyses stratified by risk factor status (eg, for smokers and nonsmokers) “are not predictable since characteristics, such as smoking, that modify the risk of coronary heart disease also modify the risk of death from competing causes”. Put simply, the increased competing risk of death from lung cancer, other cancers, and chronic lung diseases may result in a lower lifetime risk of coronary heart disease among smokers. This difficulty is likely to be less relevant to risk factors such as hypertension and dyslipidaemia, which do not cause as striking increases in risk of competing causes of death. Another complicating factor is that smoking status frequently changes during the lifetime of an individual. We are developing methodologies that should allow calculation of lifetime risk by risk factor strata, accounting for changes in the status of exposure to the risk factor. Undoubtedly, patients, clinicians, and public health programmes should continue and expand efforts to reduce the prevalence of smoking on a local, national, and global scale. In doing so, the immense population burden of smoking-related diseases will decrease. Paradoxically, the lifetime risk of coronary heart disease among former smokers might rise if fewer of them died from lung cancer and other causes, and they therefore lived on long enough to have a first coronary event. Lifetime risk of developing coronary heart diseaseDonald Lloyd-Jones and colleagues (Jan 9, p 89)1 properly assert that educating the public and healthcare policy makers about the risk of developing coronary heart disease (CHD) will help promote its prevention, screening, and treatment. However, we are dismayed by the glaring omission of smoking from their discussion. They emphasise the inadequacy of current rates of detection and treatment of hypertension and hypercholesterolaemia, and even discuss the potential benefit of hormone replacement therapy for older women. Full-Text PDF