Introduction to Epidemiology Bill Jenkins, Ph.D. Maurice Jeter, B.S. Morehouse College Spring 2004

Introduction to Epidemiology Definition: The study of distributions and determinants of diseases and conditions in human populations. epi- that which comes upon demi- people ology- the study of

Introduction to Epidemiology Three major characteristics of the science of Epidemiology Biomedical Quantitative Population-Based

Introduction to Epidemiology Science The systematic collection, organization and utilization of knowledge Purpose: To predict

Introduction to Epidemiology “…shall I tell you what knowledge is? When you know a thing, to know it, and when you do not know a thing to recognize that you do not know it. That is knowledge.” -Confucius

Introduction to Epidemiology Statistics The systematic collection, organization, analysis, and presentation of data.

Introduction to Epidemiology Health -Absence of illness and death -A complete state of physical, mental, and social well-being -Maximization of human potential

Introduction to Epidemiology Epidemiology is a blending of many sciences: As a MEDICAL science it provides understanding on the etiology and treatment of disease As a MATHEMATICAL science it provides information on quantitative applications to health problems As a SOCIAL science it provides understanding on the social factors affecting disease and the utilization of health services As a POLITICAL science it provides information on the more effective means of allocating public support for health needs

Introduction to Epidemiology Role of the Epidemiologist Case finding – Public Health Advisors Outbreak investigations – Epi Intelligence Officers (EIS) Clinical research – Clinical Epidemiologists Methodological research and consultation – Academic Epidemiologists Etiological investigations – Senior Epidemiologists

Introduction to Epidemiology Trends in Epidemiology New developments in analytical techniques Consideration of social factors in disease causation Acceptance of multi-factorial causation Increasing specification of disease

Introduction to Epidemiology Q&A Which of the following questions would be answered by an epidemiology study? Which has a stronger affinity for hemoglobin: oxygen or carbon monoxide? Does regular exercise reduce the chances of coronary heart disease among middle aged men?

Health Transitions Life Expectancy (Years) Information Age 1950-1980 Life Expectancy: 67 yrs Causes of Death: Infectious Diseases, Strokes, Cancers, Other Chronic Diseases Types of Diseases: Infectious Diseases and Chronic Diseases Major Social Forces: Computers 67 1980 Industrial Age 1100A.D.- 1850 Life Expectancy: 47 yrs Causes of Death: Infectious Diseases, Injuries, Sanitation Types of Diseases: Early Onset of Chronic Diseases Major Social Forces: Industrial Work 1950 57 1850 47 Scientific Age 1850-1950 Life Expectancy: 57 yrs Causes of Death: Infectious Diseases Types of Diseases: Infectious Major Social Forces: 1st medicines were being tested 37 Hunter Gather Period 90,000-6,000 B.C. Life Expectancy: 17 yrs Causes of Death: Infectious Diseases, Animal Attacks, Starvation, Injuries Types of Diseases: Starvation Major Social Forces: Obtaining Food 11,000 Agriculture Age 6,000 B.C.-1100 A.D. Life Expectancy: 37 yrs Causes of Death: Plague, Famine, Hunger Types of Diseases: Plague (sanitation) Major Social Forces: 1st Cities and Urbanization 17 90,000 6,000 B.C A.D Time Period

History of Epidemiology Imhotep (3000 BC) Imhotep was a physician, mathematician, and statesman. The principle cause of disease in his time was believed to be an evil spirit which entered the body through the mouth, nose or ears. Its virulence was dependent on the times and seasons. Public health programs of the period included regular clothes cleaning, use of antiseptics such as alcohol, and mosquito control.

History of Epidemiology Hippocrates (500 BC) Hippocrates (the greek father of Medicine) in his thesis: "On Airs, Waters, and Places" gives specific considerations to the patterns of disease with respect to these factors. He suggested that the cause of disease was disturbances in constitution due to such factors as place, water, climate, nutrition, and housing.

History of Epidemiology Graunt: 1600 AD John Graunt published his: “Natural and Political Observations . . . on the Bills of Mortality" in which he described the impact of the plague on the population of London. This work is considered to be the founding work for both biostatistics and epidemiology. He suggested that data should be summarized and analyzed to determine the cause and patterns of disease. In this effort he was also the first to suggest the use of life table analysis in estimating the impact of mortality.

History of Epidemiology Farr: (1850 AD) A Physician and Statistician from 1839-1879. He observed patterns of mortality among various communities, occupations, seasons and ethnic populations. He is the first to make use of what we consider the basic tool of epidemiology, comparison among groups differing in the presence of an etiologic factor. Farr established the first annual collection and analysis of health data.

History of Epidemiology Snow:(1850 AD) Used the techniques of epidemiology to establish that fact that fecal contamination was an etiologic factor of cholera in 1855 and that the spread of the disease could be minimized by stopping the use of water from the Southwark and Vauxhall water company, which took water from the polluted Thames River.

History of Epidemiology Cholera Mortality by Water Districts. London, 1854. Water District Population Deaths Southwark & Vauxhall 167,654 192 Remainder of London 1,315,781 182

History of Epidemiology Cholera Mortality by Water Districts. London, 1854. Water District Population Deaths Deaths/100,000 Southwark & Vauxhall 167,654 192 114 Remainder of London 1,315,781 182 16

History of Epidemiology Goldberger: (1900 AD) In about 1904 Goldberger began studying the development of pellagra among mill workers in Greenville, South Carolina. He observed that green vegetables were associated with low incidence and recommended its consumption throughout the year. Later, the specific cause was found to be lack of niacin an element of vitamin B, resulting in its present-day addition to milk.

History of Epidemiology Doll: (1940 AD) Beginning in 1947 Richard Doll and Austin Bradford Hill began studying the increasing incidence of lung cancer in England. They suspected the increased use of cigarettes was the cause. A retrospective study of smoking habits among lung cancer patients and other patients was initiated, and a small association was found between smoking and lung cancer.

History of Epidemiology Smoking Habits Among Cancer and Other Patients. London, 1947 Lung Cancer Cigarette Smoker Yes No Yes No Total 709 709 % who smoked 97% 92% Retrospective study of smoking habits and lung cancer 688 650 21 59

History of Epidemiology …Doll and Hill then initiated a prospective study and found a strong, consistent dose/response association between smoking and lung cancer . . . Lung Cancer Mortality per 100,000 Population/Year Stratified by Smoking Status. London, 1951 Current Smoker 104 Former Smoker 43 Non-Smoker 10