Epi Flashcards
(38 cards)
List the two ways to limit control confounding
1) Study design stage 2) Analysis of data stage
Describe randomization in terms of controlling for confounding variables. State weakness and strengths
Randomization technique hopefully distributes an equal # of subjects with the known and unknown confounders into each intervention group.
Strength:
-WIth sufficient sample size (N), randomization will likely be successful in serving its purpose (making groups “equal”)
Weakness:
- Sampel size may not be large enough to control for all known and unknown confounders
- process doesn’t guarantee successful equal distribution between all intervention groups for all known and unknown confounders
- Practical only for interventional studies
What is the definition of Epidemiology?
A public health-discipline basic science which studies the distribution and determinants of disease in populations to control disease and illness and promote health
What are some epidemiological assumptions?
- Disease occurrence is not random
- Systematic investigation of different populations can identify ASSOCIATIONS and casual/preventive factors and impact of changes can impart on health of populations
- Making comparisons is the cornerstone of systematic disease assessments/investigations
What are the 6 core functions of epidemiology?
1) Public health surveillance
2) Field investigation
3) Analytic analysis
4) Evaluations
5) Linkages
6) Policy development
What are two components of Distribution?
1) Frequencies
2) pattern (W/W/W)
What are the components of determinants?
1) Factors of exposure
2) Etiology of disease
3) Mode of transmission
4) Social/environmental/biologic elements that determine the occurrence /presence of disease
This is analytic epidemiology
What is passive surveillance?
Relies on healthcare system to follow regulations on required reportable diseases/conditions
What is active surveillance system?
Public health officials go into communities to search for new disease/condition cases
What is syndromic surveillance?
A system that looks for the pre-defined signs/symptoms of patients related to trackable-but-rare diseases/conditions
- tracks the occurrence of disease via looking for certain syndrome, symptoms, or signs. Physician and ER see symptoms of the flu: rhinorrhea, body aches, fever etc. Sadly, those are similar to other condition. however there are disease states where they have specific presentation. There’s a collection of system or signs to indicate that specific type of disease and speculate if that is it.
- It’s asking for symptoms connected to the condition that can possibly be diagnosed to the condition.
- -syndormic surivllance is like an active surveilance to look for PRE-DEFINED signs of patients related to trackable disease/conditions
What is biosurveillance?
where they take bio samples from animals, plants, and environment to assess the status of the disease.
What is Induction period?
Time between exposure and onset of disease
What is latency period?
Time between onset of disease and development of symptoms (disease detection)
What is case definition?
- It is a set of uniform criteria used to define a disease/condition for public health surveillance
- Enable public health to classify and count cases consistently across reporting jurisdictions
- A case might be classified as suspected or probable while waiting for the laboratory results to become available once the lab provides the report, the case can be reclassified as either confirmed or “not a case’ depending on the results.
- A case definition may have several sets of criteria, depending on how certain the diagnosis is. For example, during an investigation of a possible case or outbreak of measles, a person with a fever and rash might be classified as having a suspected, probable, or confirmed case of measles, depending on what evidence of measles is present
Define Epidemic
Occurrence of disease clearly in excess of normal expectancy
- community/period is clearly defined
- goal is to capture disease as early as possible
• For example, epidemic can be across the zip code, entire city. Next year, we could be talking about an explosion of flu cases much higher than year to ear bases. So next year, we talk about epidemic of flu of KC. It can be time , period or space wide in community
o Book: An outbreak or epidemic is the occurrence of more cases of disease more than expected in a given area or among a specific group of people over a particular time. Epidemology defines outbreak as an epidemic limited to localized increase in the incidence of disease such as village, town, or closed instution.
Define Outbreak
o An epidemic limited to a localized increase in the occurrence of disease
• Sometimes interchanged with the word “cluster”
• Book: Cluster is an aggregation of cases in a given area over a particular period without regard to whether the number of cases is more expected This aggregation of cases seems to be unusual . for example, the diagnosis in one neighborhood of four adults with cancer may be disturbing to residents but may well be within the expected level of cancer occurrence
Define endemic
o Constant presence of a disease within a given area or population in excess of normal elvels in other areas
o Alaways elevated compared to other parts of the global but that’s consistent for them
o (of a disease or condition) regularly found among particular people or in a certain area.
Define emergency of international concern
o An epidemic that alerts the world to the need for high vigilance (pre-pandemic labeling)
Define pandemic
o An epidemic spread world-wide (global health)
• Muti-national/muti continent affected
• For example: Ebola: defining the epidemic a public heath emergency of international concern. H1N1 flu was an pandemic in 2009.
• This alerts the world to the need for high alert
• The Answer: An epidemic occurs when a disease affects a greater number people than is usual for the locality or one that spreads to areas not usually associated with the disease. A pandemic is an epidemic of world-wide proportions.
What is an epidemic curve?
o Visual time-based depiction created during an outbreak/epidemic of the # of cases; by date of reporting
o Book: a simple visual display of the outbreak’s magnitude and time trend.
o It visually depicts:
1) The pattern (shape) of disease spread/occurrence (pattern of spread in population)
• Common/source (continuous & Intermittent)
o NOT person to person spread; derived from a common, single point source for the outbreak
o Book: Persons are exposed to the same source over a relative brief period . in fact any sudden rise in the # of cases suggests sudden exposure to a common source one incubation period earlier
2) Propagated source:
o Person-to-person spread
o I have notes on the slides itself and the textbook about the propagated and common source
• Magnitude and timing of disease occurrence
• Sentinel or index case/peak/outliers
• Start/stop/duration (time)
What are 3 elements of bias impact?
1) Source/type
2) Magnitude /strength
3) Direction
What are the two main catergoies of bias?
1) Measurement related
2) selection related
What is healthy-worker bias. Is it selection or measurement bias?
The healthy user bias is a bias that can damage the validity of epidemiologic studies testing the efficacy of particular therapies or interventions. Specifically, it is a sampling bias: the kind of subjects that voluntarily enroll in a clinical trial and actually follow the experimental regimen are not representative of the general population. They can be expected, on average, to be healthier as they are concerned for their health and are predisposed to follow medical advice, both factors that would aid one’s health. In a sense, being healthy or active about one’s health is a precondition for becoming a subject of the study, an effect that can appear under other conditions such as studying particular groups of workers
What is Self selection/participant bias. Is it selection or measurement bias?
Those that wish to participate (volunteer) may be different in some way to those that don’t volunteer or self select (refusal/non-response) to participate .
its selection bias
