British Doctors Study
Encyclopedia
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
.
To further investigate the link, the Medical Research Council
(MRC) instructed its Statistical Research Unit (later the Oxford
-based Clinical Trial Service Unit) to conduct a prospective
study into the link. This approach to medical questions was fairly new: in the 1954 "Preliminary report", the researchers felt it necessary to offer a definition of the prospective principle.
The study, when it was published in 1956, would herald a new type of scientific research, showed to relevance of epidemiology
and medical statistics
in questions of public health
, and vitally linked tobacco smoking to a number of serious diseases.
The respondents were stratified into decade of birth, sex, and their cause-specific mortality, as well as general physical health and current smoking habits, followed up in further questionnaires in 1957, 1966, 1971, 1978, 1991, and finally in 2001.
, now commonly referred to as "heart attack") occurred markedly more often in smokers.
In the follow-up reports, published every ten years (see the 2004 article for a summary) more information became available. A major conclusion of the study is, for example, that smoking decreases life span up to 10 years, and that more than 50% of all smokers die of a disease known to be smoking-related, although the excess mortality depends on amount of smoking, specifically, on average, those who smoke until age 30 have no excess mortality, those who smoke until age 40 lose 1 year, those who smoke until 50 lose 4 years, and those who smoke until age 60 lose 7 years.
The original study was run by Richard Doll
and Austin Bradford Hill
. Richard Peto
joined the team in 1971 and would, with Doll, prepare all subsequent reports for publication. Doll and Peto are both celebrated epidemiologists, and their fame is largely based on their pioneering work in the study mentioned. They would continue their work on other cardiovascular studies, for example the more recent Heart Protection Study
.
Prospective
Prospective literally means "looking forward". It can also refer to an event that is likely or expected to happen in the future. For example, a prospective student is someone who is considering attending a school — typically a high school student who is seriously considering applying to a...
cohort study
Cohort study
A cohort study or panel study is a form of longitudinal study used in medicine, social science, actuarial science, and ecology. It is an analysis of risk factors and follows a group of people who do not have the disease, and uses correlations to determine the absolute risk of subject contraction...
which ran from 1951 to 2001, and in 1956 provided convincing statistical proof that tobacco smoking
Tobacco smoking
Tobacco smoking is the practice where tobacco is burned and the resulting smoke is inhaled. The practice may have begun as early as 5000–3000 BCE. Tobacco was introduced to Eurasia in the late 16th century where it followed common trade routes...
increased the risk of lung cancer
Lung cancer
Lung cancer is a disease characterized by uncontrolled cell growth in tissues of the lung. If left untreated, this growth can spread beyond the lung in a process called metastasis into nearby tissue and, eventually, into other parts of the body. Most cancers that start in lung, known as primary...
.
Context
Although there had been suspicions of a link between smoking and various diseases, the evidence for this link had been largely circumstantial. In fact, smoking had been advertised as "healthy" for many years, and there had been no clear explanation why rates of lung cancer had soared.To further investigate the link, the Medical Research Council
Medical Research Council (UK)
The Medical Research Council is a publicly-funded agency responsible for co-ordinating and funding medical research in the United Kingdom. It is one of seven Research Councils in the UK and is answerable to, although politically independent from, the Department for Business, Innovation and Skills...
(MRC) instructed its Statistical Research Unit (later the Oxford
Oxford
The city of Oxford is the county town of Oxfordshire, England. The city, made prominent by its medieval university, has a population of just under 165,000, with 153,900 living within the district boundary. It lies about 50 miles north-west of London. The rivers Cherwell and Thames run through...
-based Clinical Trial Service Unit) to conduct a prospective
Prospective
Prospective literally means "looking forward". It can also refer to an event that is likely or expected to happen in the future. For example, a prospective student is someone who is considering attending a school — typically a high school student who is seriously considering applying to a...
study into the link. This approach to medical questions was fairly new: in the 1954 "Preliminary report", the researchers felt it necessary to offer a definition of the prospective principle.
The study, when it was published in 1956, would herald a new type of scientific research, showed to relevance of epidemiology
Epidemiology
Epidemiology is the study of health-event, health-characteristic, or health-determinant patterns in a population. It is the cornerstone method of public health research, and helps inform policy decisions and evidence-based medicine by identifying risk factors for disease and targets for preventive...
and medical statistics
Medical statistics
Medical statistics deals with applications of statistics to medicine and the health sciences, including epidemiology, public health, forensic medicine, and clinical research...
in questions of public health
Public health
Public health is "the science and art of preventing disease, prolonging life and promoting health through the organized efforts and informed choices of society, organizations, public and private, communities and individuals" . It is concerned with threats to health based on population health...
, and vitally linked tobacco smoking to a number of serious diseases.
The study
In October 1951, the researchers wrote to all registered physicians in the United Kingdom, and obtained responses in two-thirds, 40,701 of them. No further cohorts were recruited. Because of the limited sample size females were excluded from most analyses and publications focused on the male physicians.The respondents were stratified into decade of birth, sex, and their cause-specific mortality, as well as general physical health and current smoking habits, followed up in further questionnaires in 1957, 1966, 1971, 1978, 1991, and finally in 2001.
Statistical analysis
Response rates were quite high, making appropriate statistical analyses possible. The result was, that both lung cancer and "coronary thrombosis" (the then-prevalent term for myocardial infarctionMyocardial 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...
, now commonly referred to as "heart attack") occurred markedly more often in smokers.
In the follow-up reports, published every ten years (see the 2004 article for a summary) more information became available. A major conclusion of the study is, for example, that smoking decreases life span up to 10 years, and that more than 50% of all smokers die of a disease known to be smoking-related, although the excess mortality depends on amount of smoking, specifically, on average, those who smoke until age 30 have no excess mortality, those who smoke until age 40 lose 1 year, those who smoke until 50 lose 4 years, and those who smoke until age 60 lose 7 years.
Impact and personalities
The true impact of the study is difficult to gauge, as smoking was not considered a public health problem in the 1950s, and the appreciation of the problem would only grow in the ensuing decades. Nevertheless, the British doctors study was to provide conclusive evidence of linkage between smoking and lung cancer, myocardial infarction, respiratory disease and other smoking-related illnesses.The original study was run by Richard Doll
Richard Doll
Sir William Richard Shaboe Doll CH OBE FRS was a British physiologist who became the foremost epidemiologist of the 20th century, turning the subject into a rigorous science. He was a pioneer in research linking smoking to health problems...
and Austin Bradford Hill
Austin Bradford Hill
Sir Austin Bradford Hill FRS , English epidemiologist and statistician, pioneered the randomized clinical trial and, together with Richard Doll, was the first to demonstrate the connection between cigarette smoking and lung cancer...
. Richard Peto
Richard Peto
Sir Richard Peto FRS is Professor of Medical Statistics and Epidemiology at the University of Oxford.He attended Taunton's School in Southampton and subsequently studied Natural Sciences at Cambridge University....
joined the team in 1971 and would, with Doll, prepare all subsequent reports for publication. Doll and Peto are both celebrated epidemiologists, and their fame is largely based on their pioneering work in the study mentioned. They would continue their work on other cardiovascular studies, for example the more recent Heart Protection Study
Heart Protection Study
The Heart Protection Study was a large randomized controlled trialrun by the Clinical Trial Service Unit, and fundedby the Medical Research Council and the British Heart Foundation in the United Kingdom...
.
See also
- Framingham Heart StudyFramingham Heart StudyThe 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...
- Scandinavian Simvastatin Survival StudyScandinavian Simvastatin Survival StudyThe Scandinavian Simvastatin Survival Study is a multicenter clinical trial that was performed in 1990s in Scandinavia....
- Nurses' Health StudyNurses' Health StudyThe 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...