Framingham Heart Study
Encyclopedia
The Framingham Heart Study is a long-term, ongoing cardiovascular
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.
The study had been intended to last 20 years, but at that time Dawber moved to Boston and became chairman of preventive medicine, raising funds to continue the project and taking it with him.
By 1968, a fight was underway to keep the Framingham Study going in an era marked by protests, assassinations, the struggle for civil rights, and controversy surrounding America's military involvement with the Vietnam War
. 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, the study continued, and in 1971 enrolled a second generation of participants. In 1994, a more diverse sampling of Framingham residents was enrolled as the "Omni cohort." In April 2002, a third generation was enrolled in the core study, and a second generation of Omni participants was enrolled in the following year.
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
) is a normal part of aging and happens in everyone when one gets older. High blood pressure (hypertension
) and elevated serum cholesterol (hypercholesterolemia
) were also seen as normal as one gets older in the 1950s, and no treatment was initiated. These and further risk factors, e.g. homocysteine
, were continuously discovered over the years.
The Framingham Heart Study, along with other important large studies, e.g. the Seven Countries Study
, Nurses' Health Study
, Women's Health Initiative
, 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.
, including individuals without known cardiovascular disease. The Framingham Risk Score is based on findings of the Framingham Heart Study.
1960s: Cigarette smoking increases risk of heart disease. Increased cholesterol and elevated blood pressure increase risk of heart disease. Exercise decreases risk of heart disease, and obesity increases it.
1970s: Elevated blood pressure increases risk of stroke. In women who are postmenopausal, risk of heart disease is increased, compared with women who are premenopausal. Psychosocial
factors affect risk of heart disease.
1980s: High levels of HDL cholesterol reduce risk of heart disease.
1990s: Having an enlarged left ventricle of the heart (left ventricular hypertrophy
) increases risk of stroke. Elevated blood pressure can progress to heart failure. Framingham Risk Score is published, and correctly predicts 10-year risk of future coronary heart disease (CHD) events. At 40 years of age, the lifetime risk for CHD is 50% for men and 33% for women.
2000s: So called «high normal blood pressure» increases risk of cardiovascular disease (high normal blood pressure is called prehypertension
in medicine; it is defined as a systolic pressure of 120–139 mm Hg and/or a diastolic pressure of 80–89 mm Hg). Lifetime risk of developing elevated blood pressure is 90%. Obesity is a risk factor for heart failure. Serum aldosterone
levels predict risk of elevated blood pressure. Lifetime risk for obesity is approximately 50%. The «SHARe» project is announced, a genome
wide association study within the Framingham Heart Study. Social contacts of individuals are relevant to whether a person is obese, and whether cigarette smokers decide to quit smoking. Four risk factors for a precursor of heart failure are discovered. 30-year risk for serious cardiac events can be calculated. American Heart Association
considers certain genomic findings of the Framingham Heart Study one of the top research achievements in cardiology. Some genes increase risk of atrial fibrillation
. Risk of poor memory is increased in middle aged men and women if the parents had suffered from dementia
.
, physical examination
and medical tests every two years, creating a wealth of data about physical and mental health, especially about cardiovascular disease.
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.
Circulatory system
The circulatory system is an organ system that passes nutrients , gases, hormones, blood cells, etc...
study on residents of the town of Framingham
Framingham, Massachusetts
Framingham is a New England town in Middlesex County, Massachusetts, United States. The population was 68,318 as of the United States 2010 Census. -History:...
, Massachusetts
Massachusetts
The Commonwealth of Massachusetts is a state in the New England region of the northeastern United States of America. It is bordered by Rhode Island and Connecticut to the south, New York to the west, and Vermont and New Hampshire to the north; at its east lies the Atlantic Ocean. As of the 2010...
. 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
Diet (nutrition)
In nutrition, diet is the sum of food consumed by a person or other organism. Dietary habits are the habitual decisions an individual or culture makes when choosing what foods to eat. With the word diet, it is often implied the use of specific intake of nutrition for health or weight-management...
, exercise, and common medications such as aspirin
Aspirin
Aspirin , also known as acetylsalicylic acid , is a salicylate drug, often used as an analgesic to relieve minor aches and pains, as an antipyretic to reduce fever, and as an anti-inflammatory medication. It was discovered by Arthur Eichengrun, a chemist with the German company Bayer...
, is based on this longitudinal study
Longitudinal study
A longitudinal study is a correlational research study that involves repeated observations of the same variables over long periods of time — often many decades. It is a type of observational study. Longitudinal studies are often used in psychology to study developmental trends across the...
. It is a project of the National Heart, Lung, and Blood Institute
National Heart, Lung, and Blood Institute
The National Heart, Lung, and Blood Institute is a division of the National Institutes of Health, located in Bethesda, Maryland...
, in collaboration with (since 1971) Boston University
Boston University
Boston University is a private research university located in Boston, Massachusetts. With more than 4,000 faculty members and more than 31,000 students, Boston University is one of the largest private universities in the United States and one of Boston's largest employers...
. Various health professionals from the hospitals and universities of Greater Boston
Greater Boston
Greater Boston is the area of the Commonwealth of Massachusetts surrounding the city of Boston. Due to ambiguity in usage, the size of the area referred to can be anywhere between that of the metropolitan statistical area of Boston and that of the city's combined statistical area which includes...
staff the project.
History
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, but at that time Dawber moved to Boston and became chairman of preventive medicine, raising funds to continue the project and taking it with him.
By 1968, a fight was underway to keep the Framingham Study going in an era marked by protests, assassinations, the struggle for civil rights, and controversy surrounding America's military involvement with the Vietnam War
Vietnam War
The Vietnam War was a Cold War-era military conflict that occurred in Vietnam, Laos, and Cambodia from 1 November 1955 to the fall of Saigon on 30 April 1975. This war followed the First Indochina War and was fought between North Vietnam, supported by its communist allies, and the government of...
. 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, the study continued, and in 1971 enrolled a second generation of participants. In 1994, a more diverse sampling of Framingham residents was enrolled as the "Omni cohort." In April 2002, a third generation was enrolled in the core study, and a second generation of Omni participants was enrolled in the following year.
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. The initial population was 5,209 healthy men and women aged 30 to 62, not the whole of the town population, as is sometimes assumed.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
Atherosclerosis
Atherosclerosis is a condition in which an artery wall thickens as a result of the accumulation of fatty materials such as cholesterol...
, arteriosclerosis
Arteriosclerosis
Arteriosclerosis refers to a stiffening of arteries.Arteriosclerosis is a general term describing any hardening of medium or large arteries It should not be confused with "arteriolosclerosis" or "atherosclerosis".Also known by the name "myoconditis" which is...
) is a normal part of aging and happens in everyone when one gets older. High blood pressure (hypertension
Hypertension
Hypertension or high blood pressure is a cardiac chronic medical condition in which the systemic arterial blood pressure is elevated. What that means is that the heart is having to work harder than it should to pump the blood around the body. Blood pressure involves two measurements, systolic and...
) and elevated serum cholesterol (hypercholesterolemia
Hypercholesterolemia
Hypercholesterolemia is the presence of high levels of cholesterol in the blood. It is not a disease but a metabolic derangement that can be caused by many diseases, notably cardiovascular disease...
) were also seen as normal as one gets older in the 1950s, and no treatment was initiated. These and further risk factors, e.g. homocysteine
Homocysteine
Homocysteine is a non-protein amino acid with the formula HSCH2CH2CHCO2H. It is a homologue of the amino acid cysteine, differing by an additional methylene group. It is biosynthesized from methionine by the removal of its terminal Cε methyl group...
, were continuously discovered over the years.
The Framingham Heart Study, along with other important large studies, e.g. the Seven Countries Study
Seven Countries Study
The Seven Countries Study is an important epidemiological study. It is a large longitudinal study. It was the first study to systematically examine the relationships between lifestyle, diet, coronary heart disease and stroke in different populations from different regions of the world...
, Nurses' Health Study
Nurses' Health Study
The Nurses Health Study, established in 1976 by Dr. Frank Speizer, and the Nurses' Health Study II, established in 1989 by Dr. Walter Willett, are the most definitive long-term epidemiological studies conducted to date on older women's health. The study has followed 121,700 female registered...
, Women's Health Initiative
Women's Health Initiative
The Women's Health Initiative was initiated by the U.S. National Institutes of Health in 1991. The objective of this women's health research initiative was to conduct medical research into some of the major health problems of older women...
, also showed the importance of healthy diet
Healthy diet
A healthy diet is one that helps maintain or improve general health. It is important for lowering many chronic health risks, such as obesity, heart disease, diabetes, hypertension and cancer. A healthy diet involves consuming appropriate amounts of all essential nutrients and an adequate amount of...
, not being overweight
Overweight
Overweight is generally defined as having more body fat than is optimally healthy. Being overweight is a common condition, especially where food supplies are plentiful and lifestyles are sedentary...
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
Smoking
Smoking is a practice in which a substance, most commonly tobacco or cannabis, is burned and the smoke is tasted or inhaled. This is primarily practised as a route of administration for recreational drug use, as combustion releases the active substances in drugs such as nicotine and makes them...
is a highly significant factor in the development of heart disease, leading to angina pectoris, myocardial infarction
Myocardial infarction
Myocardial infarction or acute myocardial infarction , commonly known as a heart attack, results from the interruption of blood supply to a part of the heart, causing heart cells to die...
(MI), and coronary death, along with other important studies about smoking, e.g. the British Doctors Study
British Doctors Study
The British Doctors Study is the generally accepted name of a prospective cohort study which ran from 1951 to 2001, and in 1956 provided convincing statistical proof that tobacco smoking increased the risk of lung cancer.-Context:...
.
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
Evidence-based medicine
Evidence-based medicine or evidence-based practice aims to apply the best available evidence gained from the scientific method to clinical decision making. It seeks to assess the strength of evidence of the risks and benefits of treatments and diagnostic tests...
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
Social network
A social network is a social structure made up of individuals called "nodes", which are tied by one or more specific types of interdependency, such as friendship, kinship, common interest, financial exchange, dislike, sexual relationships, or relationships of beliefs, knowledge or prestige.Social...
of friends and family in the study.
Framingham Risk Score
The 10-year cardiovascular risk of an individual can be estimated with the easy to use Framingham Risk ScoreFramingham Risk Score
The Framingham Risk Score is used to estimate the 10-year cardiovascular risk of an individual. The Framingham Risk Score is based on data obtained from the Framingham Heart Study. There are two Framingham Risk Scores, one for men and one for women....
, including 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:1960s: Cigarette smoking increases risk of heart disease. Increased cholesterol and elevated blood pressure increase risk of heart disease. Exercise decreases risk of heart disease, and obesity increases it.
1970s: Elevated blood pressure increases risk of stroke. In women who are postmenopausal, risk of heart disease is increased, compared with women who are premenopausal. Psychosocial
Psychosocial
For a concept to be psychosocial means it relates to one's psychological development in, and interaction with, a social environment. The individual needs not be fully aware of this relationship with his or her environment. It was first commonly used by psychologist Erik Erikson in his stages of...
factors affect risk of heart disease.
1980s: High levels of HDL cholesterol reduce risk of heart disease.
1990s: Having an enlarged left ventricle of the heart (left ventricular hypertrophy
Left ventricular hypertrophy
Left ventricular hypertrophy is the thickening of the myocardium of the left ventricle of the heart.-Causes:While ventricular hypertrophy occurs naturally as a reaction to aerobic exercise and strength training, it is most frequently referred to as a pathological reaction to cardiovascular...
) increases risk of stroke. Elevated blood pressure can progress to heart failure. Framingham Risk Score is published, and correctly predicts 10-year risk of future coronary heart disease (CHD) events. At 40 years of age, the lifetime risk for CHD is 50% for men and 33% for women.
2000s: So called «high normal blood pressure» increases risk of cardiovascular disease (high normal blood pressure is called prehypertension
Prehypertension
Prehypertension is an American classification for cases where a person's blood pressure is elevated above normal but not to the level considered to be hypertension . The seventh report of the Joint National Committee proposed a new definition of blood pressure values below 140/90 mm Hg...
in medicine; it is defined as a systolic pressure of 120–139 mm Hg and/or a diastolic pressure of 80–89 mm Hg). Lifetime risk of developing elevated blood pressure is 90%. Obesity is a risk factor for heart failure. Serum aldosterone
Aldosterone
Aldosterone is a hormone that increases the reabsorption of sodium ions and water and the release of potassium in the collecting ducts and distal convoluted tubule of the kidneys' functional unit, the nephron. This increases blood volume and, therefore, increases blood pressure. Drugs that...
levels predict risk of elevated blood pressure. Lifetime risk for obesity is approximately 50%. The «SHARe» project is announced, a genome
Genome
In modern molecular biology and genetics, the genome is the entirety of an organism's hereditary information. It is encoded either in DNA or, for many types of virus, in RNA. The genome includes both the genes and the non-coding sequences of the DNA/RNA....
wide association study within the Framingham Heart Study. Social contacts of individuals are relevant to whether a person is obese, and whether cigarette smokers decide to quit smoking. Four risk factors for a precursor of heart failure are discovered. 30-year risk for serious cardiac events can be calculated. American Heart Association
American Heart Association
The American Heart Association is a non-profit organization in the United States that fosters appropriate cardiac care in an effort to reduce disability and deaths caused by cardiovascular disease and stroke. It is headquartered in Dallas, Texas...
considers certain genomic findings of the Framingham Heart Study one of the top research achievements in cardiology. Some genes increase risk of atrial fibrillation
Atrial fibrillation
Atrial fibrillation is the most common cardiac arrhythmia . It is a common cause of irregular heart beat, identified clinically by taking a pulse. Chaotic electrical activity in the two upper chambers of the heart result in the muscle fibrillating , instead of achieving coordinated contraction...
. Risk of poor memory is increased in middle aged men and women if the parents had suffered from dementia
Dementia
Dementia is a serious loss of cognitive ability in a previously unimpaired person, beyond what might be expected from normal aging...
.
What the study participants consented to
The Framingham Heart Study participants, and their children and grandchildren, voluntarily consented to undergo a detailed medical historyMedical history
The medical history or anamnesis of a patient is information gained by a physician by asking specific questions, either of the patient or of other people who know the person and can give suitable information , with the aim of obtaining information useful in formulating a diagnosis and providing...
, physical examination
Physical examination
Physical examination or clinical examination is the process by which a doctor investigates the body of a patient for signs of disease. It generally follows the taking of the medical history — an account of the symptoms as experienced by the patient...
and medical tests every two years, creating a wealth of data about physical and mental health, especially about cardiovascular disease.
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 AustraliaUniversity of Western AustraliaThe University of Western Australia was established by an Act of the Western Australian Parliament in February 1911, and began teaching students for the first time in 1913. It is the oldest university in the state of Western Australia and the only university in the state to be a member of the...
. 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 not investigated in the Framingham Heart Study, e.g. sleep apneaSleep apneaSleep apnea is a sleep disorder characterized by abnormal pauses in breathing or instances of abnormally low breathing, during sleep. Each pause in breathing, called an apnea, can last from a few seconds to minutes, and may occur 5 to 30 times or more an hour. Similarly, each abnormally low...
.
- 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».
Works cited
- Daniel Levy and Susan Brink. (2005). A Change of Heart: How the People of Framingham, Massachusetts, Helped Unravel the Mysteries of Cardiovascular Disease. Knopf. ISBN 0-375-41275-1.
External links
- Framingham Heart Study - official web site
- Heart Center of MetroWest - Cardiology group including William P. Castelli, MD - Former Director of Framingham Heart Study
