Clinical Epidemiology Flashcards
What is a basic science of public health that studies anything affecting population?
Epidemiology
What usually begins with outbreak of specific disease in community and identifies exposures that are associated with disease?
Study of epidemics in specific population groups
What do studies often provide?
The first indication of nature of new disease
Example: AIDS- Early 80s, many unusual cases of infection reported to CDC, epidemiologists examined shared risks and exposure in these patients to identify pathogen
Epidemiology involves the study of pattents of health and illness and associated factors at what level?
Population: Both infectious and non-communicable diseases
What are 3 reasons that epidemiology is one of the most important methods of public health research?
- It can identify risk factors for disease
- It can help determine optimal treatment approaches and prevention techniques
- Involves study design, data collection, statistical analysis, and documentation of results
Who is sometimes referred to as the father of epidemiology and why?
Hippocrates: He was the first person to examine relationships between disease and environmental influences and also coined the terms endemic and epidemic
Who identified the Broad Street pump as the cause of Soho cholera outbreak in 1854 and what was done do end the outbreak?
Dr. John Snow
-Used chlorine to clean water, then removed the pump handle
What was the 19th century cholera epidemic regarded as?
The founding event for epidemiology
What 2 types of disease does epidemiology follow?
Endemic and epidemic
Presence of disease in population at low but constant levels: Examples include common cold and heart disease?
Endemic
Sudden outbreak of disease in population, more cases than predicted within population: Examples include cholera epidemic in Haiti?
Epidemic
What is an epidemic that spreads throughout the world like AIDS or novel H1N1 Influenza?
Pandemic
What is a measure of new cases of disease or injury in population over specified time period?
Incidence
Ex: There were 34 cases of Lyme disease reported to Erie County Department of Health in 2010
-Incidence of LD in Erie County in 2010 = 34 cases
Measure of total number of cases of disease or injury in population over specified time period?
Prevalence
Ex: There are 40 students absent from class today due to influenza -Prevalence of influenza in class = 40 cases
What is prevalence at a specific point in time?
Point prevalence
Why is it important to identify the cause of disease outbreak?
Steps can be taken to treat or prevent disease in future
What can be used to identify probability of association between cause and disease outcome?
Biostatistics
True or False: Statistical association (or correlation) does not always equal causation
TRUE
-Ex: Studies have shown high correlation between number of violent crimes and ice cream consumption in a population
Cause and effect –> More likely explanation is that an area with more people is more likely to have a higher number of violent crimes committed and more ice cream consumption
What are the 9 Bradford-Hill Criteria for assessing evidence of causation?
- Strength
- Consistency
- Specificity
- Temporality
- Biological gradient
- Plausibility
- Coherence
- Experiment
- Analogy
Larger association is more likely causal effect?
Strength
Stronger association when same findings observed by different people and different samples?
Consistency
Causation likely is very specific population with specific disease and no other likely explanation
-More specificity = Bigger probability of causal effect
Specificity
Temporality?
Effect happens after the cause (CA happens after exposure to radiation)
Biological gradient?
Greater exposure causes greater incidence
Plausible mechanism between cause and effect helpful?
Plausibility
Between epidemiological and laboratory findings increases likelihood of effect?
Coherence
“Occasionally it is possible to appeal to experimental evidence?
Experiment
Analogy?
The effect of similar factors may be considered
What is a qualitative study?
Case study (case series studies)
What is a quantitative study?
Case-control studies and cohort studies
What is a qualitative study of one patient or a small group of patients with similar disease?
Case Series Studies
True or False: Case series studies are only descriptive and cannot be extrapolated to a population of patients with disease
TRUE
What compares patient exposure periods to periods when they are unexposed?
Self-controlled case-series studies
What 2 things are done in a self-controlled case-series study?
- Patients are diagnosed with the disease and followed
2. Follow-up time is divided into exposed and unexposed periods and incidence of disease compared
What is a retrospective study that looks in patient’s past for possible exposures that may have been encountered?
Case-control studies
In a case-control study, who are “cases”?
Patients diagnosed with disease
In a case-control study, who care “controls”?
Patients not diagnosed with disease
What other factors should be matched as closely as possible between cases and controls in a case-control study?
Age, sex, ethnicity, etc.
In a case-control study, once the exposure is identified, what 4 categories are cases and controls subdivided into?
- Exposed cases
- Exposed controls
- Unexposed cases
- Unexposed controls
What is the formula fr the odds ratio used in a case control study?
OR = (Exposed cases/Unexposed cases) / (Exposed controls/Unexposed controls)
If the odds ratio is greater than 1, what does this mean?
The exposure is likely associated with disease
If the odds ratio is equal to 1 or is close to 1, what does this mean?
Exposure and disease are not likely associated
What is a prospective study that selects participants based on exposure status?
Cohort study
In a cohort study do participants have the disease at the initiation of the study?
No, participants are at risk of, but don’t have the disease at the initiation of the study
So, what is actually done when in a cohort study?
The cohort is followed prospectively for development of disease
Example: Cohort of smokers and cohort of non-smokers followed over time to estimate incidence of lung cancer
In a cohort study, the cohort if followed prospectively for outcome, what are the 4 categories used?
- Cases in exposed group
- Non-cases in exposed group
- Cases in unexposed group
- Non-cases in unexposed group
What is the formula for relative risk used in a cohort study?
RR = (Cases in exposed group/Cases in exposed group + Non-cases in exposed group) / (Cases in unexposed group/cases in unexposed group + non-cases in unexposed group)
What does it mean if RR is greater than 1?
Exposure is likely associated with development of disease
What does it mean is RR is equal to 1 or close to 1?
Exposure and disease aren’t likely associated