key characteristics of epidemiology – Flashcards
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distribution
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refers to the frequency and pattern of a health-related state or event
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frequency
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the number of occurrences of a health-related state or event -relation of that number to the size of the population (rate)
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pattern
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involves presenting the distribution by person, place and time characteristics
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determinants
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collective or individual risk factor (or set of factors) that is causally related to a health condition, outcome, or other defined characteristic -mat be physical stresses, chemicals, biological, social factors
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exposures
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pertain either to contact with a disease-causing factor or to the amount of the factor that impinges upon a group of individuals
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outcomes
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all the possible results that may stem from exposure to a causal factor.. expressed as types and measures of morbidity and mortality
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morbidity
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illness due to a specific disease or health condition
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mortality
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death
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quantification
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-epi is a quantitative discipline -refers to counting the cases of illness or other health outcomes ---a standard set of criteria, or CASE DEFINITION, assures that cases are consistently diagnosed, regardless of where or when they were identified and who diagnosed the case -denotes the use of statistics to describe the occurrence of health outcomes and measure their association with exposures
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case definitions
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evolve over time -suspected -probable - contact and symptoms -confirmed - laboratory - detected presence of agent or exposure to antigen
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epidemiology aids with:
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health promotion, alleviation of adverse health outcomes, prevention of disease
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epidemiological methods are applicable to
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development of needs assessments, design of prevention programs, evaluation of the success of such programs
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epidemiology contributes to health policy development
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provides quantitative information that can be used by policy makers
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objectives of epidemiology
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-identify the ETIOLOGY (cause of a disease) and the relevant risk factors -determine the extent of disease found in the community -study the natural history and prognosis of the disease - define the baseline -evaluate both existing and newly developed preventative and therapeutic measures and modes of health care delivery -provide the foundation for developing public policy relating to environmental problems, genetic issues, and other considerations regarding disease prevention and health promotion
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prepathogenesis
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time period before the disease agent has interacted with the host
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pathogenesis
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after the agent has interacted with a host
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prodromal stage
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nonspecific symptoms (fatigue)
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3 types of prevention
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1. primary - before the disease occurs - prepathogenesis - general health promotion and specific prevention against disease - ex. immunization 2. secondary - during progression of the disease - activities that limit the progression of the disease - ex. programs for cancer screening 3. tertiary - during later stages of the disease - programs for restoring the patient's optimal functioning - ex. physical therapy
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interdisciplinary approach
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mathematics and biostatistics - quantitative methods history - historical accounts of disease sociology - social determinants of disease demography and geography - population structures and location of disease outbreaks behavioral sciences - models of disease, design of health promotion programs law - legal bases for health policy
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descriptive epidemiology
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refers to epidemiological studies concerned with characterizing the amount and distribution of health and disease within a population the 4 w's: what = health issue of concern, case definition who = person where = place when = time aim to delineate the patters and manner in which disease occurs in populations -focused on the development of hypotheses
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analytic epidemiology
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examines causal (etiologic) hypotheses regarding the association between exposures and health conditions -key feature is a comparison group --the 5th W - why/how = causes, risk factors, models of transmission
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natural experiments
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-naturally occurring circumstances in which subsets of the population have different levels of exposure to a supposed causal factor in a situation resembling an actual experiment, where human subjects would be randomly allocated to groups -things that happened and can then be used -laws or policy - flouridated water, CA law requiring hands-free driving -other events - bombing, ecoli breakout
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cohort study
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investigator records whether each study participant is exposed or not then tracks the participants to see if they develop the disease of interest
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case-control study
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investigators start by enrolling a group of people with a disease, then enrolls a group of people without the disease and compares previous exposures between the 2 groups
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cross-sectional study
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a sample of persons from a population is enrolled and their exposures and health outcomes are measured simultaneously -tends to assess the presence of the health outcome without regard to duration
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ecological study
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units of analysis are populations or groups rather than individuals
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experimental study
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investigator determines through a controlled process, the exposure for each individual (CLINICAL TRIAL) or community (COMMUNITY TRIAL) then tracks over time to detect the effects of the exposure
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hippocrates
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-a physician who became known as the father of medicine and the first epidemiologist -attempted to describe disease from a rational basis instead of a supernatural explanation -he observed that different diseases occurred in different locations ----he noted that malaria and yellow fever most commonly occurred in swampy areas -he also introduced terms like epidemic and endemic
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black death
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-thought to be an epidemic of bubonic plague, a bacterial disease cause by infection with yersinia pestis, transmitted via flea bites (from rodents to people via flea bites) -claimed up to one-third of population of europe (20 to 30 million out of 100 million) -characterized by: swollen lymph nodes, fever, appearance of black splotches on the skin
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paracelsus
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one of the founders of the field of toxicology -discipline that is used to examine the toxic effects of chemicals found in environmental venues -the dose-response relationship: effects of a poison are related to the strength of its dose ---threshold on curve: concentration at which you see first response -notion of target organ specificity of chemicals
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john graunt
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using the "bills of mortality" in london, he systematically recorded age, sex, who died, of what, where they died, and when -recorded how many persons a year died of what kind of event or disease -developed and calculated life tables and life expectancy -divided deaths into two types of causes 1. acute (struck suddenly - e.g. cholera) 2. chronic (lasted over a long period of time - e.g. emphysema)
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thomas sydenham
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-believed that observation should drive the study of the course of disease -described and distinguished different diseases including some psychological maladies -advanced useful treatments and remedies including exercise, fresh air and a healthy diet, which other physicians rejected at the time
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Bernardino Ramazzini
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-regarded as the founder of occupational medicine (what most people are exposed to at work) -observed that disease among workers arose from two causes: 1. harmful character of the materials that workers handled as the materials often emitted noxious vapors and very fine particles which could be inhaled 2. certain violent and irregular motions and unnatural postures imposed upon the body whole doing work (ergonomics)
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sir percival pott
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-thought to be the first person to describe an environmental cause of cancer -observed that chimney sweeps had high incidence of scrotal cancer in comparison with male workers in other occupations -established an occupational hygiene control measure --recommendations that chimney sweeps bathe once a week -his observation has come to be regarded as the foundation stone on which the knowledge of cancer prevention has been built
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james lind
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-wrote book a treatise on scurvy in which he identified the symptoms of scurvy --became common among sailors after as little as a month at sea -applied experimental methods to identify that eating citrus fruits were effective remedies for scurvy among sailors at sea -also made clinical observations, used experimental design, asked classical epidemiological questions, observed the population changes and its effect on disease, and considered sources of causation, including place, time and season -his work led the british navy to require that limes or lime juice be included in the diet of seamen
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benjamin jesty
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-farmer/dairyman in the mid-1700s, noticed his milkmaids never got smallpox, but did get cowpox -exposed his wife and kids to cowpox -lead to vaccinations
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edward jenner
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-developed a method for smallpox vaccination -created a vaccine by using material from the arm of a dairymaid, sarah nelmes, who had an active case of cowpox --injected into 8 year old arm --vaccinated other children
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lemuel shattuck
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-published the first report on sanitation and public health problems, which set forth the importance of establishing state and local boards of health --having an organized effort to collect and analyze vital statistics -recommended the exchange of health information, sanitary inspections, research on tuberculosis, and the teaching of sanitation and prevention in medical schools -advocate of public hygiene in the US -use data to track/prevent diseases
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john snow
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believed cholera was transmitted by contaminated water and was able to demonstrate this through 2 famous studies
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miasmatic theory of disease
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disease was transmitted by a miasm, or cloud, that clung low on the surface of the earth disease transmitted through bad air
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john snow study #1
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1854 cholera epidemic in the golden square of london -descriptive study -determined where persons with cholera lived and worked -mapped distribution of cases on a spot map -looked for clustering of cases around water pumps -identified water supply (pump) for those with cholera
