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EPIDEMIOLOGY. Catherine T. Horat RN MSN CS C-FNP NUR 410 Community Focused Nursing. Epidemiology . Definition “The study of the distribution and determinants of health-related states or events in specific populations, and the application of this study to control of health problems”
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EPIDEMIOLOGY Catherine T. Horat RN MSN CS C-FNP NUR 410 Community Focused Nursing
Epidemiology • Definition • “The study of the distribution and determinants of health-related states or events in specific populations, and the application of this study to control of health problems” Last, 2001, p. 62
Epidemiology • Studies
Epidemiology • Epidemiologic Methods used in • Health services research • Investigate associations between • To what extent Healthy People 2000 goals accomplished • Monitor progress of Healthy People 2010
Study of Distribution • Distribution • Patterns of events • Influences on • Characterized as
Descriptive Epidemiology • Based on distribution or patterns of health events in populations • Attempts to describe a disease entry according to • Person • Place • Time
Study of Determinants • Determinants of health – events or factors that determine or influence the patterns of • Questions asked
Study of Determinants • Include
Analytic Epidemiology • Investigation of causes and association • Directed toward understanding the etiology or origins and causal factors of a disease • Useful for • Guiding or evaluating policies and programs that improve the health of a community
Comparison of Analytic/Descriptive Epidemiology • Analytic studies rely on descriptive comparisons • Descriptive comparisons shed light on determinants
Epidemiology • Study of populations in order to
Key Terms • Surveillance • Endemic • Epidemic • Pandemic
Epidemiological Investigational Models • Epidemiological Triangle • Web of Causation • Person-Place-Time
Epidemiological Triangle Agent Host Environment
Epidemiological Triangle AGENT • Causative factor contributing to health problems that must be present or lacking
Epidemiological Triangle HOST • A susceptible human or animal who harbors and supports a disease causing agent • Intrinsic
Epidemiological Triangle ENVIRONMENT • All factors internal or external to a client that constitute the context in which the client lives and that influences and are influenced by the host and agent-host interactions
Web of Causation • Web of Causation • Complex interrelationships of numerous factors interacting to increase or decrease risk of disease • The determination based on EVIDENCE or REASONING process that an event or state ResultedFROM or was CAUSED BY some other events, exposure, characteristics, or a combination of them (Causality)
Causality • Criteria
Person-Place-Time • Examines the characteristics of • People affected • The place or location • Time period involved • Considered as variables • Person who is affected • Place where affected • Time when affected
Health Promotion and Disease Prevention • Natural History of Disease the course of progression of a disease from onset to resolution • Prepathogenesis period (Environment) • Disease has not developed but interactions are occurring between host, agent and environment that produce disease stimulus and increase the host’s potential for disease • Pathogenesis period (Human) • Begins when disease-producing stimuli start to produce changes in the tissues of humans
Natural History and Levels of Prevention • Primary Prevention • Prepathogenesis • Adaptation • Adaptive processes are initiated
Natural History and Levels of Prevention • Secondary Prevention • Pathogenesis • Discernable early lesions • Clinical recognition • Early DX and prompt treatment
Natural History and Levels of Prevention • Tertiary Prevention treatment to arrest disease or rehabilitation • Clinical Disease
Mortality Rates • Relative death rate • Sum of deaths in a given population at a given time • Crude mortality rate • Cause-specific mortality rate • Case fatality rate • Age-specific death rate • Proportional Mortality Ratio
Mortality Rates • Crude mortality rate includes • based per on 100,000 population • #deaths in a year______ Average midyear population • Ex • # 10,000deaths in St. Petersburg, Fl in 2002 X 100,000 # 350,000of persons in St. Petersburg Fl in July 1, 2002
Mortality Rates • Cause-specific actual cause of deaths desired to be measured • per 100,000 • EX #75 of men who died from pneumonia in St. Petersburg Fl in 2003 X100,000 # 60,000 of men in total population of St. Petersburg, FL, 2003
Mortality Rates • Case-fatality • #deaths due to a specific disease X100 cases # cases of specific disease • EX 25 deaths from E-coli X 100 cases 300 cases of E-coli
Mortality Rates • Age-specific • Enables comparing populations in different locations • EX # 120 deaths among 45 year olds in Denver CO in 2005 X 100000 # 10,000 of 45 year old people in Denver CO July 1
Mortality Rates • Proportional • Compares number of deaths from a particular cause with deaths from all other causes # deaths from specific cause in a specified time period X 100 Total # deaths in same time period # 200 of Cancer deaths in 2001 X 100 # 5000 of total deaths from all causes in 2001
Morbidity Rates • Relative incidence of disease • Incidence • Prevalence
Morbidity Rates • Incidence • Rates that measure ALL NEW CASES arising in a population during a defined period of time, usually 1 year # of new cases in place during time of observation X K Population in place at midpoint of time 60 new mump cases from 1/07 to 1/08 X 100,000 50,000 population • K = unit of population
Morbidity Rates • Prevalence measures total number of persons with a characteristic with the total number in the population • 50 people with chicken pox X K 1000 people in population