The Framingham Heart Study is a long-term, ongoing cardiovascular cohort study on residents of the town of Framingham, Massachusetts. The study began in 1948 with 5,209 adult subjects from Framingham, and is now on its third generation of participants. Prior to it almost nothing was known about the "epidemiology of hypertensive or arteriosclerotic cardiovascular disease". Much of the now-common knowledge concerning heart disease, such as the effects of diet, exercise, and common medications such as aspirin, is based on this longitudinal study. It is a project of the National Heart, Lung, and Blood Institute, in collaboration with (since 1971) Boston University. Various health professionals from the hospitals and universities of Greater Boston staff the project.
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History
In 1948, the study was commissioned by Congress, with a decision made between Framingham, Massachusetts or Paintsville, Kentucky. Framingham was ultimately chosen when it had shown more general interest in heart research than Paintsville. Thomas Royle Dawber was Director of the study from 1949 to 1966. He was appointed as chief epidemiologist shortly after the start of the project, when it was not progressing well. The study had been intended to last 20 years, however interest grew in part due to Dr. Dawber's continuing to promote the study and engage in fundraising after he had been transferred to Boston to accept a chairmanship of preventive medicine. By 1968, it was debated whether the original study had served its purpose and should be terminated as scheduled. A committee gathered and considered that, after 20 years of research, the Framingham study should come to an end, since their hypothesis had been tested and extensive information concerning heart diseases had been gathered. Despite this conclusion, Congress failed to accept the recommendation, instead voting to continue the study. The study had been split into different segments, or "cohorts".
- The Original Cohort, founded in 1948, consisted of 5,209 men and women. Requirements for entry was a minimum age of 30 to maximum age of 62 at the time of first examination, with no history of heart attack or stroke. Due to lukewarm interest at first, doctors, nurses and healthcare workers volunteered for the study to set an example for patients.
- The Offspring Cohort, founded in 1971, was a second generation study where children of the Original Cohort were eligible. Spouses were also eligible if they had become pregnant with (or sired) two or more children by a participant in the Offspring Cohort.
- The Omni Cohort, founded in 1994, looked at the possibility of race and heritage in heart factors, as well as the changing racial background of Framingham. It mirrored the Original Cohort by asking people of color to volunteer.
- The Generation Three Cohort, founded in 2002, was a third generation study consisting of children of the Offspring Cohort and/or grandchildren of the Original Cohort participants. Minimum age for acceptance was 20.
- The Omni Two Cohort, founded in 2003, was a second generation study consisting of children of Omni Cohort participants. While the Original Cohort had been spaced over decades, the Omni Cohort had a much shorter generational window. On account of this, participants as young as 13 years of age were eligible for the Omni Two Cohort.
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Strong and weak points
Over 1000 medical papers have been published related to the Framingham Heart Study. It is generally accepted that the work is outstanding in its scope and duration, and overall is considered very useful.
It was rightly assumed from the start of the Framingham Heart Study that cardiac health can be influenced by lifestyle and environmental factors, and by inheritance. The Framingham Heart Study is the origin of the term risk factor. Before the Framingham Heart Study, doctors had little sense of prevention. In the 1950s, it was believed that clogging of arteries and narrowing of arteries (atherosclerosis, arteriosclerosis) was a normal part of aging and occurred universally as people became older. High blood pressure (hypertension) and elevated serum cholesterol (hypercholesterolemia) were also seen as normal consequences of aging in the 1950s, and no treatment was initiated. These and further risk factors, e.g., homocysteine, were gradually discovered over the years.
The Framingham Heart Study, along with other important large studies, e.g., the Seven Countries Study, Nurses' Health Study, also showed the importance of healthy diet, not being overweight or obese, and regular exercise in maintaining good health, and that there are differences in cardiovascular risk between men and women. It also confirmed that cigarette smoking is a highly significant factor in the development of heart disease, leading to angina pectoris, myocardial infarction (MI), and coronary death, along with other important studies about smoking, e.g., the British Doctors Study.
Recently the Framingham studies have become regarded as overestimating risk, particularly in the lower risk groups, e.g., for UK populations.
One question in evidence-based medicine is how closely the people in a study resemble the patient with which the healthcare professional is dealing. There has been discussion of the study in this regard.
Researchers recently used contact information given by subjects over the last 30 years to map the social network of friends and family in the study.
Framingham Risk Score
The 10-year cardiovascular risk of an individual can be estimated with the Framingham Risk Score, including for individuals without known cardiovascular disease. The Framingham Risk Score is based on findings of the Framingham Heart Study.
Major findings
Major findings from the Framingham Heart Study, according to the researchers themselves:
Study Design
The Framingham Heart Study participants, and their children and grandchildren, voluntarily consented to undergo a detailed medical history, physical examination, and medical tests every two years, creating a wealth of data about physical and mental health, especially about cardiovascular disease. A nonprofit charity, called Friends of the Framingham Heart Study, was founded to help defray study costs and spread awareness of heart issues. Membership is limited to participants.
Genetic research
In recent years, scientists have been carrying out genetic research within the Framingham Heart Study.
Inheritance patterns in families, heritability and genetic correlations, molecular markers, and associations have been studied. The association studies include traditional genetic association studies, i.e., looking for associations of cardiovascular risk with gene polymorphisms (single-nucleotide polymorphisms, SNPs) in candidate genes, and genome wide association studies (GWAS). For example, one genome wide study, called the 100 K Study, included almost 1400 participants of the Framingham Heart Study (from the original cohort, and the offspring cohort), and revealed a genetic variant associated with obesity. The researchers were able to replicate this particular result in four other populations. Further, the SHARe Study (SNP Health Association Resource Study) uncovered new candidate genes, and confirmed already known candidate genes (for homocysteine and vitamin B12 levels) in participants of the Framingham Heart Study.
Because of these exciting genomic results, the Framingham Heart Study has been described as "on its way to becoming the gold standard for cardiovascular genetic epidemiology".
However, clinically, despite these (and other) efforts, the aggregate effect of genes on cardiovascular disease risk beyond that of traditional cardiovascular risk factors has not been established until now.
Similar studies
- Busselton Health Study has been carried out since 1966 in a high proportion of the residents of Busselton, a town in Western Australia, over a period of many years. A database has been compiled and is managed by the School of Population Health at the University of Western Australia. Although the results of the Busselton Health Study and the Framingham Heart Study are similar in many aspects, the Busselton Health Study investigated also the influence of some factors that had not been investigated in the Framingham Heart Study, e.g., sleep apnea.
- The Caerphilly Heart Disease Study, also known as the Caerphilly Prospective Study (CaPS), is an epidemiological prospective cohort, set up in 1979 in a representative population sample drawn from a typical small town in South Wales, UK. The study has collected wide ranging data and has led to over 400 publications in the medical press, notably on vascular disease, cognitive function and healthy living.
- China-Cornell-Oxford Project, also known as "China-Oxford-Cornell Study on dietary, lifestyle and disease mortality characteristics in 65 rural Chinese counties". This study was later referred to as "China Study I". The successor study is named "China Study II".
Source of the article : Wikipedia
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