Removal of the barriers to entering and receiving services or working within any health care setting.
An appreciation of the need to account for chance and bias has led to development of methods where new treatments are compared to either a PLACEBO or to the standard treatment (or both) in a controlled, randomised clinical trial. ‘Controlled’ means that there is a comparison group of patients not receiving the test intervention, and ‘randomised’ implies that patients have been assigned to one or other treatment group entirely by chance and not because of their doctor’s preference. If possible, trials are ‘double-blind’ – that is, neither the patient nor the investigator knows who is receiving which intervention until after the trial is over. All such trials must follow proper ethical standards with the procedure fully explained to patients and their consent obtained.
The conduct, e?ectiveness and duplication of clinical trials have long been subjects of debate. Apart from occasional discoveries of deliberately fraudulent research (see RESEARCH FRAUD AND MISCONDUCT), the structure of some trials are unsatisfactory, statistical analyses are sometimes disputed and major problems have been the – usually unwitting – duplication of trials and non-publication of some trials, restricting access to their ?ndings. Duplication occurs because no formal international mechanism exists to enable research workers to discover whether a clinical trial they are planning is already underway elsewhere or has been completed but never published, perhaps because the results were negative, or no journal was willing to publish it, or the authors or funding authorities decided not to submit it for publication.
In the mid 1980s a proposal was made for an international register of clinical trials. In 1991 the NHS launched a research and development initiative and, liaising with the COCHRANE COLLABORATION, set out to collect systematically data from published randomised clinical trials. In 1994 the NHS set up a Centre for Reviews and Dissemination which, among other responsibilities, maintains a database of research reviews to provide NHS sta? with relevant information.
These e?orts are hampered by availability of information about trials in progress and unpublished completed trials. With a view to improving accessibility of relevant information, the publishers of Current Science, in 1998, launched an online metaregister of ongoing randomised controlled trials.
Subsequently, in October 1999, the editors of the British Medical Journal and the Lancet argued that the case for an international register of all clinical trials prior to their launch was unanswerable. ‘The public’, they said, ‘has the right to know what research is being funded. Researchers and research funders don’t want to waste resources repeating trials already underway.’ Given the widening recognition of the importance to patients and doctors of the practice of EVIDENCE-BASED MEDICINE, the easy availability of information on planned, ongoing and completed clinical trials is vital. The register was ?nally set up in 2005.... clinical trials
Central to an understanding of public health is recognition that public-health practitioners are concerned not just with individuals, but also with whole populations – and that improving health care plays only a part of public-health improvement. The health of populations (public health) is also dependent on many factors such as the social, economic and physical environment in which the people live and the nutrition and health care available to them.
For thousands of years, a fundamental feature of civilisations has been to seek to improve the health of the population and protect it from disease. This has led to the development of legal frameworks which di?er widely from country to country, depending on their social and political development. All are concerned to stop the spread of infectious diseases, and to maintain the safety of urban food and water supplies and waste disposal. Most are also associated with housing standards, some form of poverty relief, and basic health care. Some trading standards are often covered, at least in relation to the sale and distribution of poisons and drugs, and to controls on industrial and transport safety – for example, in relation to drinking and driving and car design. Although these varied functions protect the public health and were often originally developed to improve it, most are managerially and professionally separated from today’s public-health departments. So public-health professionals in the NHS, armed with evidence of the cause of a disease problem, must frequently act as advocates for health across many agencies where they play no formal management part. They must also seek to build alliances and add a health perspective to the policies of other services wherever possible.
Epidemiology is the principal diagnostic method of public health. It is de?ned as the study of the distribution and determinants of health-related states in speci?ed populations, and the application of this study to the control of health problems. Public-health practitioners also draw on many other skills, such as those of statisticians, sociologists, anthropologists, economists and policy analysts in identifying and trying to resolve the health problems of the societies they serve. Treatments proposed are likely to extend well beyond the clinic or hospital and may include recommendations for measures to resolve poverty, improve sanitation or housing, control pollution, change lifestyles such as smoking, improve nutrition, or change health services. At times of acute EPIDEMIC, public-health doctors have considerable legal powers granted to enable them to prevent infection from spreading. At other times their work may be more concerned with monitoring, reporting, planning and managing services, and advocating policy changes to politicians so that health is promoted.
The term ‘the public health’ can relate to the state of health of the population, and be represented by measures such as MORTALITY indices
(e.g. perinatal or infant mortality and standardised mortality rates), life expectancy, or measures of MORBIDITY (illness). These can be compared across areas and even countries. Sometimes people refer to a pubic health-care system; this is a publicly funded service, the primary aim of which is to improve health by the use of population-based measures. They may include or be separate from private health-care services for which individuals pay. The structure of these systems varies from country to country, re?ecting di?erent social composition and political priorities. There are, however, some general elements that can be identi?ed:
Surveillance The collection, collation and analysis of data to provide useful information about the distribution and causes of health and disease and related factors in populations. These activities form the basis of epidemiology, which is the diagnostic backbone of public-health practice.
Intervention The design, advocacy and implementation of policies to improve health. This may be through the provison of PREVENTIVE MEDICINE, environmental measures, in?uencing the behaviour of individuals, or the provision of appropriate services to limit disability and handicap. It will lead to advocacy for health, promoting change in many areas of policy including, for example, taxation and improved housing and employment opportunities.
Evaluation Assessment of the ?rst two steps to assess their impact in terms of e?ectiveness, e?ciency, acceptability, accessibility, value for money or other indicators of quality. This enables the programme to be reviewed and changed as necessary.
The practice of public health The situation in the United Kingdom will be described as, even though systems vary, it will give a general impression of the type of work covered. HISTORY Initially, public-health practice related to food, the urban environment and the control of infectious diseases. Early examples include rules in the Bible about avoiding certain foods. These were probably based on practical experience, had gradually been adopted as sensible behaviour, become part of culture and ?nally been incorporated into religious laws. Other examples are the regulations about quarantine for PLAGUE and LEPROSY in the Middle Ages, vaccination against SMALLPOX introduced by William Jenner, and Lind’s use of citrus fruits to prevent SCURVY at sea in the 18th century.
It was during the 19th century, in response to the health problems arising from the rapid growth of urban life, that the foundations of a public-health system were created. The ‘sanitary’ concept was fundamental to these developments. This suggested that overcrowding in insanitary conditions was the cause of most disease epidemics and that improved sanitation measures such as sewerage and clean water supplies would prevent them. Action to introduce such measures were often initiated only after epidemics spread out of the slums and into wealthier and more powerful families. Other problems such as the stench of the River Thames outside the Houses of Parliament also led to a demand for e?ective sanitary control measures. Successive public-health laws were passed by Parliament, initially about sanitation and housing, and then, as scienti?c knowledge grew, about bacterial infections.
In the middle of the 19th century the ?rst medical o?cers of health were appointed with responsibility to report regularly and advise local government about the measures needed to control disease and improve health. Their scope and responsibility widened as society changed and took on a wider welfare role. After more than a century they changed as part of the reforms of the NHS and local government in the 1960s and became more narrowly focused within the health-care system and its management. Increased recognition of the multifactorial causes, costs and limitations of treatment of conditions such as cancer and heart disease, and the emergence of new problems such as AIDS/HIV and BOVINE SPONGIFORM ENCEPHALOPATHY (BSE) have again showed the importance of prevention and a broader approach to health. With it has come recognition that, while disease may be the justi?cation for action, a narrow diseasetreatment-based approach is not always the most e?ective or economic solution. The role of the director of public health (the successor to the medical o?cer of health) is again being expanded, and in 1997 – for the ?rst time in the UK – a government Minister for Public Health was appointed. This reffects not only a greater priority for public health, but also a concern that the health effects of policy should be considered across all parts of government.
(See also ENVIRONMENT AND HEALTH.)... public health
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