epidemiology key concepts

Question 1

define epidemiology

Answer 1

“Epidemiology is the study of the distribution and determinants of health-related states or events in specified populations and the application of this study to control of health problems”

Question 2

define the numerator and denominator

Answer 2

numerator - number of ppl within the popultion who are affected

denominator = the population, without the denominator and a time frame the statistic is meaningless

Question 3

study designs:
what is a a case series study?

Answer 3

a series often consecutive, of cases with the same disease

Question 4

study designs:
what is an ecological case study?

Answer 4

a population case study when a unit of study is a population and not an individual

• useful to study signs and symptoms, look at characteristics of cases for causal hypotheses (generates a hypothesis)
• descriptive, retrospective and observational

Question 5

study designs:
what is a cross sectional design study?

Answer 5

a sample of he population is taken and the proportion of the population is estimated which has:
- different exposures
- different signs/symptoms
- different outcomes

the data can be used to:
- describe prevalence/burden
- explore associations

Question 6

study design:
what is a case control study design?

Answer 6

• cases with an outcome are selected
• controls without an outcome are selected
• the exposure in cases and controls are explored and compared
• the association is then identified

Question 7

study design:
what is a cohort study design?

Answer 7

• people without an outcome are selected
• they are classified according to an exosure (such as a certain treeatment)
• they are then followed over a period of time and then results over time are compared
  
  • this can be prospective (looking forward) or retrospective (looking at the past)
• the risk of disease in exposed versus unexposed is compared

Question 8

study design:
what is quasi-experimental study design?

Answer 8

• it is a non-random allocation study, and can be an intervention (group which is tested) but the control group is not required though commonly used
• the researcher is not in control of treatments, so it depends on existing groups - not new groups
• this is to establish the cause and effect relationship between dependent and independent variables

Question 9

study design:
what is a randomised control trial?

Answer 9

• random allocation and there is an intervention involved (group which is being tested)
• control/comparators: one group is randomly given the intervention, the other group is then given a placebo or a standard treatment and then a comparison is made
• the risk of outcome in intervention and control groups is compared

Question 10

study design:
what are the objectives of each of the following study designs?

1. RCT
2. cohort
3. quasi-experimental
4. case-control
5. cross-sectional

Answer 10

Question 11

define standardisation

Answer 11

“A set of techniques, based on weighted averaging, used to remove as much as possible the effects of differences in age or other confounding variables in comparing two or more populations.”

Question 12

what is the concept of direct standardisation?

Answer 12

Question 13

what is the concept of indirect standardisation?

Answer 13

Question 14

define ‘confounding’

Answer 14

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.”

Question 15

define ‘bias’

Answer 15

bias - “An error in the conception and design of a study – or in the collection, analysis, interpretation, reporting, publication, or review of data – leading to results or conclusions that are systematically (as opposed to randomly) different from truth”