GoConqr has a new look! Let us know what you think.

Sign up free

Flashcards

Epidemiology

tasheny wilson English 36 cards

Cards in this deck (36)

  1. 1what are the major categories of analytic designs?1. case control
    2. cohort
    3. ecologic
    4. intervention studies
  2. 2what is the importance of analytic studies and what are the examples?1. lead to the prevention of disease
    ex: Framingham study is a community cohort which contributed to the understanding of risk factors associated with heart disease
    2.assist in creation of quantitative evaluations of intervention programs (quasi experimental designs) ex: those directed at the reduction of the incidence of STDs
    3. aid in determining safety &efficacy of new drugs & other procedures
  3. 3what are the two categories of analytic studies?1. observational design: the investigator does not have control over exposure factor & is usually unable to assign subjects randomly to study conditions
    2.experimental design: investigator controls who is exposed to a factor of interest and assigns subjects randomly to study groups
  4. 4what are the seven factors that characterizes study designs?1. who manipulates the exposure factor?
    -obervational or experimental
    2. how many observations are made?
    -observations made once=cross-sectional,ecologic &case-control
    -more than once =cohort &experimental
    3.what is the directionality of exposure?
    -Retrospective approach =case-control
    -single point in time= cross-sectional
    -prospective approach=experimental &cohort
    4.what are the methods of data collection?
    -either existing data (ecologic) or previously new data
    5. what is the timing of data collection?
    -recall bias
    6. what is the unit of observation?
    -can be individual or group units
    -most epidemiology study designs uses an individual unit but ecologic uses group as the unit
    7. how available are the study subjects?
    -certain classes of subjects may not be available due to ethical issues
  5. 5observational studies include what?1.ecologic studies
    2.case-control studies
    3.cohort studies
  6. 6what are ecologic studies?-" a study in which the units of analysis are populations or groups of people"
    -examples of groups include nations,states, counties etc
    -may be used when individual measurements are not available, but group-level data can be obtained
    -Ecological Comparison Study involves an assessment of the association b/w exposure rates and disease rates during the same time period
    -Ecologic Correlation is an association between two variables (exposure & outcome) measured at the group level
  7. 7what is an ecological fallacy?an erroneous inference that may occur because an association observed between variables on an aggregate (group) level does not necessarily represent or reflect the association that exists at an individual level
    example: worldwide, richer cities have higher rates of coronary heart disease than poorer cities, it would be incorrect to infer that richer individuals have higher rates of CHD than poorer individuals. In fact, in industrialized cities poorer people have higher CHD rates than richer ones
  8. 8what are the advantages of ecologic studies?advantages:
    - May provide information about the context of health
    -can be performed when individuals-level measurements are not available
    -can be conducted rapidly and with minimal resources
  9. 9what are the disadvantages of ecologic studies?-ecologic fallacy
    -imprecise measurement of exposure
  10. 10what is a case-control study?-subjects are defined on the basis of the presence or absence of an outcome of interest
    -cases are those individuals who have the outcome or disease of interest, whereas the controls do not
  11. 11what is a matched-case control study?is one in which the cases and controls have been matched according to one or more criteria such as sex, age, race, or other variable
    -matching aids in controlling confounding
    males-->malaria...... the confounding is that males worked outside more
  12. 12what is Odds Ratiois a measure of the association between frequency of exposure and frequency of outcome used in case-control studies
    formula= AD/BC
    OR>1= positive association between exposure and disease
    OR<1= exposure might be a protective factor (like sunscreen, mosquito nets)
    OR 2.1 (2)= suggests that the odds of disease are about 2 times higher among the exposed than among the non-exposed
    OR=1.0 indicates no association between exposure and outcome (not statistically relevant)
  13. 13what are the advantages of case-control studies?1. can be used to study low prevalence conditions
    -having a disease is a criterion for being selected as a case
    2. relatively quick and easy to complete
    3. usually inexpensive
    4. involves smaller number of subjects
  14. 14what are the disadvantages of case-control studies?1. measurement of exposure may be inaccurate
    2. Representativeness of cases and controls may be unknown (don't know how similar cases & controls are to the general public)
    3. provide indirect estimates of risk
    4. the temporal relationship between exposure factor and outcome cannot always be ascertained
  15. 15what is a cohort study?a cohort is defined as a population group, or subset thereof (distinguished by a common characteristic), that is followed over a period of time
    Examples: birth or age cohort, work cohort, school/educational cohort
  16. 16what are the different types of cohort studies?-retrospective
    -prospective
    -historical prospective
  17. 17what is a prospective cohort study?subjects are classified according to their exposure to a factor of interest, and then are observed over time to document the occurrence of new cases (incidence) of disease or other health event
    -how many new cases of illness occur?
    -framingham study=longest cohort
  18. 18what is a retrospective cohort study?-makes use of historical data to determine exposure level at some baseline in the past
    -follow-up for subsequent occurrences of disease between baseline & present is performed
    -Example: a study of mortality among an occupational cohort of shipyard workers employed at a specific naval yard during a defined time interval in the past
    -past-->past/present
  19. 19what is a historical prospective cohort study?combines retrospective and prospective approaches
  20. 20what is the difference between retrospective cohort and a case-control study?an entire cohort of exposed individuals is examined in a retrospective cohort while a case-control study makes use of a limited number of cases and controls who usually do not represent an entire cohort of exposed individuals
  21. 21what is the measure of association used in cohort studies?Relative Risk: the ratio of the incidence rate of a disease or health outcome in an exposed group to the incidence rate of the disease or condition in a non-exposed group
    RR=incidence rate in the exposed/incidence rate in the non-exposed
    RR= [A/(A+B)]/[C/(C+D)]
    interpretation of RR is same as Odds Ratio
  22. 22what is attributable risk &population attributable risk?-attributable, in a cohort study, refers to the difference between the incidence rate of a disease in the exposed group and the incidence rate in the non-exposed group
    [A/A+B]- [C/C+D]
    -population attributable risk is the incidence in the total population minus incidence in the non-exposed
    -both are synonymous
  23. 23what are the advantages of cohort studies?1. permit direct observation of risk
    2. exposure factor is well defined
    3. can study exposures that are uncommon in the population
    4. the temporal relationship between factor and outcome is known
  24. 24what are the disadvantages of cohort studies?1. expensive and time consuming
    2. complicated and difficult to carry out
    3. subjects may be lost to follow up during the course of the study
    4. exposures can be misclassified
  25. 25what are experimental studies?-in epidemiology, experimental studies are implemented as intervention studies
    -An intervention study is "an investigation involving intentional change in some aspect of the status of the subjects"
    *Randomized control trial (RCT)
    *Quasi-experimental design
  26. 26what is RCT randomized controlled trialsubjects in a population are randomly allocated into groups, usually called study & control groups, to receive or not to receive an experimental preventative or therapeutic procedure, maneuver, or intervention
    -placebos & real treatments
  27. 27what are the four different RCT trials?1. prophylactic trial=is designed to test PREVENTATIVE measures
    2. therapeutic trials= evaluate new TREATMENT methods
    3. Clinical trials= refers to " a research activity that involves the administration of a test regimen to humans to evaluate its efficacy and safety
    4. Crossover design= participants may be SWITCHED between treatment groups
  28. 28what is a community intervention?is an intervention designed for the purpose of educational & behavioral changes at the population level
    - most community interventions are quasi-experimental designs (can't control everything, meaning researchers do not randomly assign themselves)
  29. 29what is a quasi-experimental study?is a type of research in which the investigator manipulates the study factor but DOES NOT assign individual subjects randomly to the exposed & non-exposed groups
    * let people self-assign into their groups (those who do & don't smoke)
  30. 30what are program evaluations?used to determine whether the program meets stated goals and is justified economically
  31. 31what are the challenges to the validity of study designs?-external validity
    -sampling error
    -internal validity
    -bias
  32. 32what is external validity?refers to ones ability to generalize from the results of the study to an external population
    -a convenience sample (grab bag sample) may not demonstrate external validity [because people who are included does not represent population at a whole]
    -random samples are More Likely to demonstrate external validity than convenience samples
  33. 33what is a sampling error?a type of error that arises when values (statistics) obtained for a sample differ from the values (parameters) of the parent population
  34. 34what is internal validity?refers to the degree to which the study has used methodologically sound procedures (using the scale & height measurer in a hospital, or buying a scale & measuring tape)
  35. 35what are bias in epidemiological studies-epidemiological studies may be impacted by bias, which is "systematic deviation of results or inferences from the truth"
    1. hawthorne effect
    2.recall bias
    3. selection bias
    4. healthy worker effect
    5. confounding
  36. 36describe the different types of bias1. hawthorne effect: participants' behavioral changes as a result of their knowledge of being in a study
    -ex: participants try to lose weight when they learn that weight would be taken
    2. Recall bias: cases may remember an exposure more clearly than controls
    3. Selection bias: distortions that result from procedures used to select subjects and from factors that influence participation in the study
    4. Healthy worker effect: the observation that employed populations tend to have a lower mortality experience than the general population
    5. Confounding: the distortion of a measure of the effect of an exposure on an outcome due to the association of the exposure with other factors that influence the occurrence of the outcome
    -example: age

Information

Description
Flashcards on Epidemiology, created by tasheny wilson on 21/10/2016.
Created by
tasheny wilson
Views
2
Rating

Feedback

What is it about?

What do you think of the new look?

How do you like it?