Term
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Definition
| Study of distribution and determinants of states or events in specified populations, and the application of this study to the control of health problems |
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Term
| Key Elements: Epidemiology “Triad” |
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Definition
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Term
When we think of studying “disease”,
is “disease” a stable concept? |
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Definition
NO because
1. Cultural values can influence definitions and perceptions of disease (especially psychiatric disorders).
2. Improvements in diagnostic instrumentation can lead to earlier detection of asymptomatic disease.
3. Clinical thresholds for disease classification change over time.
culture values can influence |
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Term
| Why do we study the epidemiology of diseases in large populations, such as the community, rather than focusing on treatment settings? (means why not do study on hospital setting instead of community) |
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Definition
Because:
1. Early development of disease can be assessed more readily in the community.
2. Many individuals with disease do not seek treatment.
3. Many individuals with disease do not have access to or the resources to receive treatment.
4. The co-occurrence of multiple diseases, and ascertainment of familial risks, is better accomplished through an epidemiological framework.
5. Threshold levels between sub-clinical and clinical disease are better determined from individuals not in treatment settings. |
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Term
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Definition
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Term
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Definition
| Endemic: Habitual presence of a disease among the population of a given geographic area. |
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Term
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Definition
| Epidemic: Occurrence of a group of illnesses of similar nature within a given community or region in excess of normal expectancy, and derived from a common source or from a propagated source. |
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Term
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Definition
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Term
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Definition
| Herd immunity: Resistance of a group to an attack by a disease to which a large proportion of members of the group are immune. |
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Term
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Definition
Virulence: Severity of the disease produced by the organism.
Usually expressed as a ratio; number of cases of overt infection/number of total infections |
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Term
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Definition
| Carrier: Individual who harbors the organism but is NOT infected, as measured by serologic studies or evidence of clinical illness. |
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Term
| what is Infectivity? give example |
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Definition
Infectivity: Capacity of agent to enter and multiply in a susceptible host (hence produce infection/disease).
Ratio of number of persons developing clinical illness/number of exposed individuals.
Ex. Polio and measles have high infectivity |
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Term
| What is Pathogenicity? give example |
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Definition
Pathogenicity: Capacity of agent to cause clinical disease in the infected host. some bac might be more in the body but would not produce infection so they have less pathogenicity.
Ex. Measles has high pathogenicity |
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Term
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Definition
| Toxigenicity: Capacity of agent to produce a toxin or poison |
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Term
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Definition
Resistance: Ability of agent to survive adverse environmental conditions (hepatitis agents generally very resistant whereas influenza viruses are typically fragile).
Note: “resistance” is also applied to the host. |
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Term
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Definition
Antigenicity: Ability of agent to induce antibody production in the host (e.g. re-infection with measles virus is very rare).
The related term “immunogenicity” refers to infection’s ability to produce specific immunity. |
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Term
| what are two modes of disease transmission? |
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Definition
Direct: Person-to-person contact (propagated).
Indirect:
a) Common vehicle such as contaminated air or water supply (can occur from single, multiple, or continuous exposure)
b) Vector such as a mosquito (e.g. West Nile virus)
The likelihood of disease transmission depends on several related factors (see upcoming slides) |
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Term
| what is the name of term define as "time during which the host can infect another host? |
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Definition
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Term
| ___________ :: time interval from infection to development of infectiousness |
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Definition
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Term
| ______________ : time from infection to development of symptomatic disease. |
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Definition
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Term
| ____________ : period in which symptoms of the disease are present. |
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Definition
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Term
Why do outbreaks occur?
4 reasons .. |
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Definition
1.Increase in amount or virulence of agent
2.Recent introduction of the agent into a new setting
3.Enhanced mode of transmission, exposing more susceptible individuals
4.Factors that increase host exposure or involve introduction through new portals of entry
Ex. Population growth, tissue and organ transplantation, drug use, food processing and packaging, global warming, etc. |
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Term
| 2 conditions for an out break |
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Definition
1 Agent and susceptible hosts are present in sufficient number
2 The agent can effectively be conveyed from a source to susceptible hosts |
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Term
| what are some utility (benefits) of performing outbreak investigation? |
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Definition
1. Has goal of determining cause of outbreak, eliminating or interrupting transmission, and providing post-exposure prophylaxis.
2. Uncovers new infectious agents and diseases.
3. Identifies spread of a known virus to a new geographic area (e.g. West Nile encephalitis in New York City).
4. Improves epidemiological understanding by uncovering new means of disease transmission.
5. Leads to public health regulations/recommendations to prevent future disease outbreaks. |
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Term
| what are Four Unique Features of Infectious Diseases? |
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Definition
1. A case may also be a source:
2. Some people may be immune:
3. There is sometimes a need for urgency: example, Legionnaires disease
4. Preventive measures (often) have a clear scientific basis. |
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Term
| morbidity and mortality lec begins |
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Definition
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Term
| what are 4 Quantitative Measures of Health Status? |
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Definition
They include:
• Counts
• Proportions
• Ratios
• Rates |
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Term
| there are 4 Quantitative Measures of Health Status. which one is Useful for allocation of health resources? |
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Definition
Count: Refers to the number of cases of a disease or
other health phenomenon being studied |
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Term
occurrence of major depression
2:1 female to male
what kind of Quantitative Measures of Health Status? |
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Definition
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Term
| __________ tells us the fraction of the population that is affected. (Persons included in the numerator are always included in the denominator) |
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Definition
Proportion :
P = A / (A + B) = (1,400 / 11,050) = 0.127 |
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Term
| A ratio in which TIME forms part of the denominator is called ____________ |
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Definition
Rates.
Rates contain defined time interval, # of events occurring in that time interval, estimate of the population at risk in the time interval, |
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Term
1. ______________ tell us how fast the disease is occurring in a population.
2. ________________ tell us what fraction of the population is affected |
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Definition
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Term
| what is the formula for incidence rate? |
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Definition
1000 X Number of new events during a time period= GGGGG
then GGGGG/population at risk. |
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Term
| _________________ is a measure of the risk of developing some new condition within a specified period of time. |
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Definition
| Incidence is a measure of the risk of developing some new condition within a specified period of time. |
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Term
| An ________________ is an incidence rate calculated for a specific disease for a limited period of time during an epidemic (---how fast is it attack?) |
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Definition
| An attack rate is an incidence rate calculated for a specific disease for a limited period of time during an epidemic (---how fast is it attack?) |
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Term
| how do you calculate Attack rate? |
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Definition
| Attack rate is defined as the number of exposed persons infected with the disease divided by the total number of exposed persons |
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Term
| what is period prevalence? |
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Definition
| Period prevalence measures the frequency of all current events (old and new) for a prescribed period of time |
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Term
| point prevalence definition -- under stand on your own... |
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Definition
according to pp: Point prevalence measures the frequency of all current events (old and new) at a given instant in time (a set time that you decided----)
Book: point prevalence is like photo; new cases in that time period divided by people at risk of exposure.
period prevalence is like video; from one point of time to this instance. so old and new cases divided by people at risk.
retarded..i hate this exam.. |
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Term
Proportion of individuals who become diseased during a specified period of time
(e.g. all new cases during 1998) is called __________________ |
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Definition
Cumulative Incidence (CI)
impt : Also referred to as “incidence proportion.” |
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Term
| when somebody observe a group of individuals for a period of time in order to ascertain the development of an event it is called __________ |
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Definition
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Term
In a 2-year study of the development of
disease X, why might the actual
time each individual is observed vary? |
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Definition
Because:
Subjects may be recruited at different times
Subjects may emigrate
Subjects may choose to leave study
Subjects may die
Subjects may get the disease we are studying |
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Term
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Definition
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Term
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Definition
| The application of a disease-detection test to people who are as yet asymptomatic. |
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Term
| Screening for Disease Control purpose ? |
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Definition
| to classify individuals with respect to their likelihood of having a particular disease |
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Term
| what is the objective of screening? |
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Definition
| To lower morbidity and mortality of the disease in a population (control, rather than elimination of disease). |
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Term
| why is screening important? two reasons |
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Definition
1) Diagnostic and therapeutic advances are often slow, but screening may be a “direct solution” to modify history of a disease in a population.
2) It provides a model for studying disease mechanisms and the natural history of a disease. |
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Term
| (4) Primary requirements for screening: |
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Definition
1. disease should be like breast cancer --early detection could give favorable prognosis.
2. Pre-clinical disease left untreated typically progresses to clinically-evident disease (e.g. no spontaneous regression).
3. The disease should be serious (relates to cost effectiveness, ethics, and prognosis).
4) Prevalence of pre-clinical disease should be relatively high among those screened. |
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Term
| what is Total Pre-Clinical Phase (TPCP)? |
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Definition
Begins at the initiation of disease (exposure);
ends when the disease is clinically manifested (25 years in this example) |
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Term
| what is Detectable Pre-Clinical Phase (DPCP)? |
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Definition
| DPCP: Begins when screening test is able to detect disease; ends when disease is clinically evident (10 years) |
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Term
| what are four critical characteristics of screening? |
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Definition
1. Validity
2. Reliability
3. Low cost, minimally invasive, and minimally uncomfortable
4. performance |
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Term
| what are four critical characteristics of screening? |
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Definition
1. Validity
2. Reliability
3. Low cost, minimally invasive, and minimally uncomfortable
4. performance |
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Term
| Validity of screening test should include what two things |
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Definition
1. The test will actually classify a diseased person as likely to have the condition --> (“sensitivity”).
2. The test will actually classify a non-diseased person as unlikely to have the condition -->(“specificity”). |
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Term
| practice calculation of Validity of screening test |
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Definition
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Term
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Definition
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Term
know this statement
If you want to draw a cause-effect conclusion, you must run an experimental design or strategy. |
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Definition
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Term
| for true experimental strategy what are 4 key features? |
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Definition
A. Manipulation of an independent variable
B. Control condition (-----e.g in human, trying to control condition is very difficult)
C. Random assignment of participants to groups ----( |
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Term
The experimental design is the considered the “crown jewel” of designs because, if done properly, it allows:
what kind of conclusion? |
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Definition
Causal Inference = a conclusion where one variable or event causes another.
Also called a cause-effect conclusion |
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Term
| extraneous variables give example |
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Definition
Sometimes extraneous variables that the researcher was unaware of can influence the dependent variable.
drink coffee --> CVD
but Drink coffee and smoke --> CVD
smoking is extraneous variable which could influence the dependent variable (coffee). |
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Term
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Definition
| Refers to a loss of participants during the course of the study. |
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Term
| what are two main sources of bias? |
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Definition
1. Participant Bias or Demand Characteristics
-Cues or feature in an experiment that may lead a participant to respond in a particular fashion.
lowering cholestrol meds study would be compromised if subject changes his diet habits.so dont tell
2. Experimenter Bias (Rosenthal Effect)
The experimenter knows how participants are expected to respond and may unwittingly coach them to respond in a particular way. |
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Term
| what is the best way to conduct an experiment? --like what kind of study |
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Definition
The best way to deal with both of the above biases is to utilize a “Double-Blind” procedure.
Neither the participants nor the experimenter knows who is in each experimental condition |
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Term
| what is primary out come? impt |
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Definition
Primary Outcome: The main efficacy variable being studied
Ex. Lower BP, better-controlled DM, absence of symptoms |
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Term
| what is secondary outcome? |
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Definition
Additional variables thought to be important
Ex. Quality of life, return of normal function, patient satisfaction, (Minoxidil--hair growth secondary effect) |
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Term
| clinical trial phase I -- describe |
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Definition
researchers test an experimental drug or treatment
small group of people (10-80)
first time to be evaluated
determine safety, safe dosage range, and identify side-effects |
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Term
| describe Clinical trial phase II |
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Definition
Phase II - experimental study drug or treatment given to a larger group of people (100-300)
see if it is effective, further evaluate its safety |
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Term
| describe Phase III of clinical trial |
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Definition
Phase III - experimental study drug or treatment given to large groups of people (1,000-3,000)
confirm its effectiveness, monitor side effects, compare it to commonly used treatments, and collect information that will allow the experimental drug or treatment to be used safely |
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Term
| describe Phase IV of clinical trial |
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Definition
| Phase IV - post-marketing studies delineate additional information including the drug's risks, benefits, and optimal use |
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Term
| is Informed consent a contract? |
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Definition
| Informed consent is not a contract, and the participant may withdraw from the trial at any time |
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Term
| what happens in crossover assignment study? |
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Definition
In a double-blind, crossover study, however, participants receive either real treatment or placebo for a time, and then are switched ("crossed over") to the opposite treatment. Thus, researchers can get double mileage out of their participants—each person gets both placebo and treatment.
-- so if botox was given for 4 months, and then change it to placebo. if the wrinkles do not get better with placebo then it positive results for drug.
you are doing two studies on one pt. do not have to get more people for placebo |
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Term
| Observational studies ..damn this is boring |
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Definition
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Term
| what is a difference between observational study and intervention study? |
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Definition
The term “observational study” refers to the fact that the investigator takes advantage of natural events and studies them.
on the other hand, intervention study is like clinical trial. |
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Term
| what are Three types of non-causal associations? |
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Definition
1. Chance association
2. artifiactual association that occur through some error or defect in the design or execution of a study.
3. Indirect associations in which an exposure is associated with an outcome but through a third factor or variable.1 |
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Term
| what are two types of observational studies? |
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Definition
1. Descriptive epidemiolgical studies attempt to describe patterns of disease and antecedent factors as they occur in “free-range” human populations.
2. Analytic studies-- ? |
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Term
| descriptive observational studies fall in what three types? read in detail on slide 7,8 and 9 if you want to |
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Definition
1. Case report: 3 pt psychotic episode after reality show
2. cross-sectional studies: main points Does lack of exercise cause chest pain?
Or does chest pain lead to lack of exercise
3. Ecological studies: These are large-scale studies that provide population-wide estimates of disease rates vs. exposure status.
For example, data are often presented comparing various countries around the world. --fat intake and breast cancer |
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Term
| what are two different studies that fall under analytic studies? |
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Definition
Cohort and Case control studies
read this in detail from power point. |
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Term
| Studies in which the exposure and outcome have already occurred are termed _____________________ |
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Definition
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Term
| Studies in which the outcome has yet to occur are called ______________. |
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Definition
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Term
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Definition
| This ratio is called the relative risk---the risk of people who is healthy at the beginning of getting the disease |
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Term
| give three advantages of retrospective studies. |
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Definition
1. cost- cheaper than prospective
2. time- no need to follow up with subject
3. rare outcomes- Prospective studies are not very efficient when studying diseases or health events that are rare |
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Term
| in retrospective Case control studies, it begin with the ____________ and proceed to look back at the history of exposure. |
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Definition
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Term
| Fu*k everything is red...case control studies from slide 21.. study on your own |
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Definition
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Term
| study last lec on your own i m tired |
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Definition
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Term
| The phenomenon of being removed from a study through death from other causes is referred to as ___________________. |
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Definition
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Term
| Sensitivity should be increased when..3 cases |
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Definition
a. the penalty associated with missing a case is high (e.g. minimize false negatives)
b. when the disease can be spread
c. when subsequent diagnostic evaluations are associated with minimal cost and risk |
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Term
| Specificity should be increased when |
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Definition
| the costs or risks associated with further diagnostic techniques are substantial (minimize false positives – e.g. positive screen requires that a biopsy be performed). |
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Term
Sources of Controls includes 5 things
question could be except which one so know all of them |
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Definition
1. General population
2. Random digit dialing
3. Neighborhood
4. Friends/relatives
5. Hospital or clinic-based |
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