2: Practical Applications of Epidemiology Flashcards
Seven Uses of Epidemiology
- to study the HISTORY of the health of populations
- to DIAGNOSE the health of the community
- to study the working of health services-OPERATIONS RESEARCH
- to estimate the INDIVIDUAL RISKS of disease and other conditions, and the chances of avoiding them
- to IDENTIFY SYNDROMES
- to complete the CLINICAL PICTURE of chronic diseases
- to SEARCH FOR CAUSES of health and disease
Historical Use of Epidemiology
refers to the study of past and future trends in health and illness. EX. secular trends
Secular Trends
changes in disease frequency over time
factors affecting reliability of observed changes over time
- lack of comparability over time due to altered diagnostic criteria
- aging of the general population
- changes in the fatal course of the condition
trends that reduce reliability of morbidity and mortality
- New Epidemic Disorders
- Persisting Disorders
- Residual Disorders
- Disappearing Disorders
- New Epidemic Disorders
Disease that are increasing in frequency.
-HIV, Type 2 Diabetes, Asthma, Obesity
- Persisting Disorders
Diseases for which there is no effective method of prevention or no known cure.
-cancer, mental disorders
- Residual Disorders
Conditions for which the key contributing factors are largely known. Methods of control not implemented effectively.
-STDs, alcohol abuse, tobacco use
- Disappearing Disorders
Conditions that were one common but are no longer present in epidemic form. Immunizations, sanitary conditions, antibiotics, etc. led to eradication of these diseases.
-smallpox, polio, measles
Syphilis
- Bacterial STD, only human->human
- treated with antibiotics
- 80% asymptomatic
Tuberculosis
-Bacterial, airborne and respiratory transmission
Polio
- Virus
- food, water, fecal & oral transmission
three factors that affect size of populations
- births
- deaths
- migration
population equilibrium
when births, deaths, or migration don’t contribute to net increases or decreases
Fixed Population
adds no new members and, as a result, decreases in size due to deaths only
Dynamic Population
adds new members through migration and births or loses members through emigration and deaths
Demographic Transition
shift from high birth and death rates found in agrarian societies to lower birth and death rates found in developed countries
Epidemiologic Transition
shift in the pattern of morbidity and mortality from infectious and communicable diseases to chronic, degenerative diseases.
Steady Population
close to equilibrium
Variables Related to Community Infrastructure
- availability of social and health services
- quality of housing stock (apartments vs. homes)
- social stability (residential mobility, employment opportunities)
Health-Related Outcome Variables
- Homicide and Suicide rates
- Infant Mortality rate
- Selected Mortality rates
- Drug and Alcohol Abuse rates
- Teen Pregnancy rates
- Birth rate
Health People 2020
- Achieve health equity, eliminate disparities, and improve health of all groups
- Attain high-quality, longer lives free of preventable disease, disability, injury, and premature death
- Create social and physical environments that promote good health for all
- Promote quality of life, health development, and healthy behaviors across all stages of life
Gini Index
income inequality. Ranges from 0 (equal) - 1 (high inequality)
Disparities
differences
Operations Research
the study of the placement and optimum utilization of health services in a community
Program Evaluation
uses epidemiologic tools to determine how well a health program meets certain stated goals
Causality in epidemiologic research
- research is subject of criticism
- many conflicting studies
- Henle-Koch postulates not relevant to many contemporary diseases
- multivariate causality
How are Henle-Koch postulates not relevant to many contemporary diseases?
- “Agent present in every disease” vs. chronic diseases
- “One agent-one disease” vs. CVD
- “Exposure of healthy subjects to suspected agents” vs. smoker never gets lung cancer
Rick Factors definition
exposure that is associated with a disease
Three Criteria for Risk Factors
- Frequency of disease varies by category or value of factor
- Risk factor precedes onset of disease
- Observation must not be due to error
Modern concepts of causality
- Strength of association
- Consistency upon repetition
- Specificity (miners vs. black lung)
- Time sequence
- Biologic gradient (dose-response relationship)
- Plausibility
- Coherence of explanation
- Experiment (natural experiments)
- Analogy (similar associations)
Case-Control Study design
- compares persons with disease (cases) with those who are free of the disease (controls)
- explores whether differences between groups result from exposures to risk factors
Case-Control Study examples
- cell phone use and brain cancer
- high HPV load and potential for cervical cancer
Cohort Study design
group (cohort) of people free from a disease is assembled according to a variety of exposures and is followed over a period of time for development of disease, health risks, or behaviors.
considerations that determine a study’s influence
- criteria of causality
- relevance to each patient (size of risk)
- public health implications (individual vs. population)
Prevention of Disease
epidemiological research is applied to identify where ina disease’s natural history effective intervention might be implemented
Natural History of Disease
refers to the course of disease from its beginning to its final clinical end points
Prepathogenesis
before agent reacts with host
Pathogenesis
after agent reacts with host
Clinical End Points
recovery, disability, or death
Primary Prevention
- occurs during prepathogenesis
- includes health promotion, education and specific protection against diseases
- active vs. passive
Active Primary Prevention
necessitates behavior change on the part of the subject. EX. vaccinations and wearing protective devices
Passive Primary Prevention
does not require any behavior change. EX. fluoridation of public water and vitamin fortifications of milk and bread products
Secondary Preventioin
-occurs during pathogenesis
-designed to reduce the progress of disease
EX. cancer and diabetes screening programs, Plan B for pregnant teens
Tertiary Prevention
- designed to limit disability from disease
- also directed at rehabilitation
