11-Clinical Epidemiology Flashcards
This si the basic science of public health that studies anything affecting population.
Epidemiology
Since epidemiology studies epidemics in a specific population group, it identifies what 2 properties of the epidemics?
The outbreak of specific disease
Exposures that are associated with disease
What did the epidemiologists examine to identify the AIDS pathogen in the 1980s?
Shared risks and exposures
like all the ppl who got it has unprotected sex and/or used IV drugs and stuff like that
Which level does epidemiology study the patterns of health and illness and associated factors?
Population level
True or False: epidemiology only studies infectious diseases at the population level and doesnt include non-communicable diseases.
False
it studies both
What are the 3 reasons that epidemiology is one of the most importnat mothods of public health research?
- ID risk factors for disease
- Helps determine optimal Tx and prevention
- Involves study design, data collection, statistical analysis, and documentation of results.
Who is the father of epidemiology?
Hippocrates
What did Hippocrates examine the relationships between for the first study of epidemiology?
Between disease and environmental influences
The examination of relationships between disease and environmental influences by Hippocrates causedthe coining of what 2 terms?
Endemic and epidemic
Who was the dude who identified the broad street pump as the cause of Sogo cholera outbreak in 1854?
Dr. John Snow
What did Dr. snow do to end the cholera outbreak?
Cleaned the water with chlorine and then removed the pump handle
Why is it important to ID the cause of disease outbreak?
so steps can be taken to treat or prevent disease in the future
What can be used to identify probability of association between cause and disease outcome?
Biostatistics
Why doesnt this make sense:
Countries with higher cell phone use have a higher incidence of pet dogs. So in order to get a pet dog, you need to have a cell phone.
Correlation doesnt prove causation
Richer countries have higher instances of cell phone use and prevalence of pet dogs, but there is no causation between the 2.
Who was the dude in 1965 who made detailed criteria for assessing evidence of causation?
Austin Bradford-Hill
What are the 9 components of the Bradford-Hill criteria?
Strength, Consistency, Specificity, Temporality, Biological gradient, Plausability, Coherence, Experiment, and Analogy
What increases the strength on the Bradford-hill criteria?
larger association
(more people with C diff are in the hospital than in the general population, so theres some strength in causal effect between C diff and being hospitalized)
What increases the consistency on the Bradford-hill criteria?
Stronger association when same finding observed by different people and different samples
(C diff prevalence is CONSISTENT among hospitals throughout the country)
What increases the specificity on the Bradford-hill criteria?
causation if very specific population with specific disease and no other explanation
What increases the temporality on the Bradford-hill criteria?
Effect happens after the cause
like cancer after exposure to radiation
What increases the biological gradient on the Bradford-hill criteria?
Greater exposure causes greater incidence
more radiation –> more cancer
What increases the plausability on the Bradford-hill criteria?
plausibly mechanism between the cause and effect is helpful
CT’s poop radiation –> pts that get CT’s get cancer –> CT’s cause cancer??
What increases the coherence on the Bradford-hill criteria?
Coherence between epidemiological and lab findings increases likelihood of effect
(finding C diff spores in poop of patients leaving the hospital –> hospitalized pts get C diff)
How often is it possible to appeal to experimental evidence on the Bradford-hill criteria?
Occasionally
What increases the Analogy on the Bradford-hill criteria?
The effect of similar factors
Apple is to fruit as C diff is to \_\_\_\_\_ A. Banana B. Bacteria C. diff D. Poop
Answer: shut up.
What is the one type of qualitative study for epidemiological studies?
Case studies
What are the 2 quantitative studies for epidemiological studies?
Case-control studies
Cohort studies
This is a qualitative study of one pt or small group of pts with similar disease.
Case series studies
True or False: since case series studies provides a study of a group of pts with similar disease, it can be extrapolated to a population of pts with disease.
False.
Case series studies are only descriptive
In a self-controlled case-series study, what periods do you compare for the pt?
Compare pt exposure periods to unexposed periods
This is a study that is retrospective that looks in a pts past for possible exposures that may have been encountered.
Case CONTROL studies
like when Dr. House sends his docs to the pts house to look for etiologic exposures
In case-control studies, what 2 pts must be matches as closely as possibly on other factors such as age, sex, ethnicity, etc.
Cases (pts with disease)
Controls (pts without the disease)
So in a case-control study, how can u divide the exposed pts?
into exposed cases (A) or exposed controls (B)
And in a case-control study, how can u divide the unexposed pts?
into unexposed cases (C) and unexposed controls (D)
If the odds ratio [(A/C)/(B/D)] is > 1, what does that mean?
Exposure is likely associated with disease
Basically, if hospitals are our exposure and C diff is our disease, if there are 10/100 people in the hospital with C diff (A) and there are 1/100 people out of the hospital with C diff (C), our numerator (A/C) = 10/1 = 10.
And if there are 90/100 in the hospital without C diff (B) and 99/100 out of the hospital without C diff (D), our denominator (B/D) = 0.9/0.99 = 0.91
To put it together: 10/0.99 = 11, which is > 1, so we can say that hospitals are likely associated with C diff infections.
This is to help and not confuse so sorry if I confused. Just made it up.
If the odds ratio [(A/C)/(B/D)] is < 1, what does that mean?
Exposure and disease are not likely associated
not writing out another explanation, that took too long lol.
These are studies that are prospective studies that select participants based on exposure status.
Cohort studies
True or False: in cohort studies, participants are at risk of, but do not have, disease at initiation of the study.
True
After selecting participants, what does a cohort study do to the participants?
Follow them prospectively for the development of disease
like a cohort of smokers and cohort of non-smokers followed over time to estimate incidence of lung cancer
What is the relative risk (RR) eqn for cohort studies?
RR = (A/A + B)/(C/C + D)
If the RR > 1, what does the cohort study show?
exposure is likely associated with development of the disease
Example- if lung CA is our disease and smoking is our exposure, if 85/100 of lung cancer pts smoke (A) and 10/100 of smokers DO NOT develop lung CA, then our numerator (A/A+B) = (0.85/0.85 + 0.10) = 0.89
If there are 15/100 of lung CA pts that dont smoke (C) and there 90/100 of the population does not develop lung CA and there is no smoking (D), our denominator (C/C+D) = (0.15/0.15+0.90) = 0.14
All together: RR = 0.89/0.14 = .89/.14 = 6, which is > 1, so there is an associated with smoking and the development of lung CA.
If the RR < 1 or close to 1, what does the cohort study show?
Exposure and disease are not likely associated
Is RR more powerful or weak measure than Odd ratio (OR)?
More powerful
What are the 10 steps of outbreak investigation?
- Prepare for fieldwork
- Establish existence of outbreak
- Verify diagnosis
- Define and identify cases
- Describe data in terms of time, place, person
- Develop hypotheses
- Evaluate hypotheses
- Refine hypotheses, carry out additional studies
- Implement control and prevention measures
- Communicate findings
During the preparation for field work in outbreak investiagation, what must you do?
Research disease, gather supplies/equipment, and consult all partients to determine your role
What constitutes an existence of outbreak?
If observed # of cases > expected #
To verify the Dx in outbreak investigation, in addition to clinical findings and lab results, what must you do with the pt?
Visit them and barrage them with questions
In an outbreak investigation, what is a “case”?
A pt with the disease
What are the 4 usual components of a case in an outbreak investigation?
clinical info
characteristics about pts affected
info about location or place
time during which outbreak ocurred
What’s the difference between passive and active surveillance?
Passive is jsut like a letter describing the situation
Active is telephone or visit to facilities to collect info
For any disease, which 4 data components must u collect to define and identify cases in an outbreak investigation?
ID
Demographics
Clinical info (Sx and date of onset)
Risk factor info
During an outbreak investigation, what is “descriptive epidemiology?”
what information is reliable and informative.
What does the description of data in terms of time, place, and person show in an outbreak investigation?
Trends over time, geographic extent, populations affected
What 3 things does an epi curve show you in an outbreak investigation?
- Where u are in the course of epidemic
- Probable time period of exposure
- Shape determines pattern of epidemic, exposure time, and incubation
What might be the epidemic if there is a steep up slop and gradual down slope?
Single source epidemic
What might be the epidemic if there is a plateau instead of a peak?
Continuous common source epidemic
What might be the epidemic if there is a series of progressively taller peaks 1 incubation apart?
person-person spread epidemic
What map shows where affected people live, work, and may have been exposed in an outbreak investigation?
Spot map
Why might a spot map be misleading?
If size of population varies between areas affected
like if a town of 20,000 has 10,000 affected individuals, that’s huge cuz 50% of the population is affected. but if a large town of 2 million has 30,000 affected, the spot map will show more affected in the large town even though % wise the small town is getting rammed.
During the development of the hypothesis in an outbreak ivestigation, what should are the 3 things u should address?
- source of agent
- mode of transmission
- possible exposures
During the evaluation of hypotheses during an outbreak investigation, what must you comparte hyptheses to?
Established facts
What are the 2 possible studies to use analytic epidemiology during the evaluation of hypotheses during an outbreak investigation?
Cohort study (exposure) Case-control study (disease)
Which study is better for a small, well-defined outbreak: cohort or case-control study?
Cohort
like gastroenteritis in ppl who attended a wedding
In a cohort study, after identifying the item, what should you do?
calculate relative risk for item
Which study is better for large population: cohort or case-control study?
Case-control
like the smoking/lung CA we said before or getting HepA from a restaurant in a small town.
When do you refine hypotheses and carry out out additional studies in an outbreak investigation?
when analytic epidemiological studies do not confirm hypotheses
During an outbreak investigation, when should the implementation of control and prevention measures be done?
ASAP
What are the 2 forms of commincating your findings during an outbreak investigation?
Oral briefing for local health authoritis
Written report
