Introduction to Epidemiology (Dr. Sania Rizgalla) PDF

Epidemiology Objectives: 1.identify the etiology, cause, of disease and risk factors-that is, factors that increase a person's risk for disease. 2.determine the extent of disease found in the community 3.study natural history and prognosis of disease. 4.evaluate new p...

Epidemiology Objectives: 1.identify the etiology, cause, of disease and risk factors-that is, factors that increase a person's risk for disease. 2.determine the extent of disease found in the community 3.study natural history and prognosis of disease. 4.evaluate new preventive and therapeutic measures and modes of health care delivery. 5.provide foundation for developing public policy and regulatory decisions relating to environmental problems, genetics issues, disease prevention, and health promotion About us. Epidemiology is the basic science of preventive and social medicine. It deals with the study of disease distribution and causation, prevention, health and health related events occurring in human population. Epidemiology is a fundamental science of public health has major contributions to improving population health,is essential to the process of identifying and mapping emerging diseases. There is often a frustrating delay between acquiring epidemiological evidence and applying this evidence to health policy. History of Epidemiology: Epidemiology originates from Hippocrates’ observation more than 2000 years ago that environmental factors influence the occurrence of disease. However, it was not until the nineteenth century that the distribution of disease in specific human population groups was measured to any large extent. This work marked not only the formal beginnings of epidemiology but also some of its most spectacular achievements. The finding by John Snow that the risk of cholera in London was related to the drinking of water supplied by a particular company provides a well-known example. Snow’s epidemiological studies were one aspect of a wide-ranging series of investigations that examined related physical, chemical, biological, sociological and political processes. Comparing rates of disease in subgroups of the human population became common practice in the late nineteenth and early twentieth centuries. This approach was initially applied to the control of communicable diseases but proved to be a useful way of linking environmental conditions or agents to specific diseases. In the second half of the twentieth century, these methods were applied to chronic non-communicable diseases such as heart disease and cancer, especially in middle and high-income countries :Modern Epidemiology Epidemiology in its modern form is a relatively new discipline1 and uses quantitative methods to study diseases in human populations to inform prevention and control efforts.Modern epidemiology accommodates multiple exposures contributing to increased risk for one disease (many-to-one) and situations where one risk factor contributes to multiple diseases (one-to-many). MEANING : Epidemiology is derived from the word epidemic ( epi= among; demos = people; logos = study) The foundation of epidemiology was laid in 19th century. In 1927 W.H. Frost became the first professor of epidemiology in U.S DEFINITION: is the branch of medical science which treats epidemics. ( Parkin, 1873) The science of the mass phenomena of infectious diseases. ( Frost, 1927) The study of disease, any disease, as a mass phenomenon (Greenwood, 1934) JOHN M. LAST Epidemiology, as defined by Last, is “the study of the distribution and determinants of health-related states or events in specified populations, and the application of this study to the prevention and control of health problems”. Epidemiologists are concerned not only with death, illness, and disability, but also with more positive health status and, most importantly, with the means to improve health. The term “disease” encompasses all unfavorable health changes, including injuries and mental health. In simple terms, epidemiology is the study of how the disease is distributed in populations and the factors that influence or determine this distribution. AIMS OF EPIDEMIOLOGY: To describe the distribution and magnitude of health and disease problems in human populations. To identify the aetiological factors. To provide the data essential to the planning, implementation and evaluation of services for the prevention, control and treatment of disease and to the setting up of priorities among those services. To eliminate or reduce the health problem or its consequences. To promote the health and well being of society as a whole. EPIDEMIOLOGICAL APPROACH : Epidemiological approach to problems of health and disease is based on 2 major foundations. a) Asking question b) Making comparison ASKING QUESTIONS : Epidemiology is a means of learning or asking questions a) What is the event? (the problem) b) What is the magnitude? c) Where did it happen? d) When did it happen? e) Who are affected? f) Why did it happen? RELATED TO HEALTH ACTION : A) What can be done to reduce this problem and its consequences? B) How can it be prevented in the future? C) What action should be taken by the community? D) What resources are required? E) What difficulties may arise? MAKING COMPARISONS : The basic approach in epidemiology is to make comparisons and draw inferences. This may be comparison of two or more groups – one group having the disease and the other not having the disease or comparison between individuals. The epidemiologist find the differences in the host and the environment, between those affected and not affected. Before making comparisons is to ensure what is known as “ comparability ”between the study and control groups. Both the groups should be similar so that “like can be compared with like”. For example – the study and control groups should be similar with regard to age and sex composition and similar other pertinent variable. Thanks