Analytical epidemiology – Flashcards
Unlock all answers in this set
Unlock answersquestion
What is analytic epidemiology?
answer
- Testing the hypothesis - Addressing the question of "why" - Seeks to explain already observed patterns - Usually more rigorous study design, so more expensive "Why are certain groups at higher or lower risk of disease than others"
question
What are some key concepts in analytic epidemiology?
answer
- Exposure and outcome - Exposure (E) independent variable (Risk factor, determinant, treatment, intervention) - Outcome (D) dependent variable (Health state, disease, death, survival, cure)
question
Exposure leads to what?
answer
Outcome
question
If exposure occurs & then we look for outcome it is a what?
answer
Prospective study
question
What are some key features of study designs?
answer
- Artificial manipulation of exposure (E) (experimental/observational)? - Information on exposure (E) and outcome (D) collected concurrently or in separate time period? - Direction of study from E>>D (forward) or D>>E (backward)? - Timing between study and occurrence of E and D (retrospective/prospective)?
question
What are different types of analytical studies?
answer
Experimental: Randomized control trials (RCT) Observational: Cross-sectional, longitudinal (case control, cohort)
question
What are randomized control trials (AKA cohort) ?
answer
- Most rigorous of the studies - Random allocation of population into 2 groups (experimental or control) - Blinding (double blinded? Placebo?) - Results observed at some future time (ALWAYS prospective) - Ethical/logistical problems - Direction always E>D
question
Describe cohort (prospective) studies
answer
- Tracks groups of individuals over time - Selection based on exposure (E) - Forward directionality E>D (PROSPECTIVE) - Study one exposure, many outcomes - Not suitable for studying rare disease - Prospective VS. retrospective - Measure: RELATIVE RISK(RR)
question
Describe control studies
answer
- Selection based on outcome/disease - Backward directionality E<D (RETROSPECTIVE) - Study one disease many exposures - Persons with rare disease of interest (cases) are compared to another group without the disease (controls) - Purpose: Do 2 groups differ in proportion of exposure to specific risk factors? - Measure: ODDS RATIO (OR)
question
What are advantages to case control studies?
answer
- Inexpensive - First step in hypothesis testing - Good for rare conditions/chronic diseases - Can look for multiple risk factors/exposures
question
What are some disadvantages to case control studies?
answer
- Past information may not be available or recall bias - Selection of control subjects may be difficult - Temporal relationship may be unclear
question
What is measures of association?
answer
- Relative risk (RR) or odds ratio (OR) - Depends on type of study - RR for cohort studies - OR for case-control studies - Either can be used for cross-sectional studies
question
What does relative risk (cohort studies) look at?
answer
The ratio of the incidence of a health outcome (disease) among the exposed to that among the unexposed
question
If result of Relative risk (RR) is 1 it means what?
answer
Risk is equal
question
If result of Relative risk (RR) is > 1 it means what?
answer
Risk is greater in exposed group
question
If result of Relative risk (RR) is < 1 it means what?
answer
Risk is less in exposed group
question
What does odds ratio (case control studies, retrospective) look at?
answer
The ratio of the odds in favor of having a specific health condition when the suspected factor is present, (exposure among diseased) to the odd in favor of having the condition when the factor is absent (exposure among non-diseased)
question
If the result of Odds ratio (OR) is 1 it means what?
answer
The odds are equal
question
If the results of Odds ratio (OR) is > 1 it means what?
answer
The odds are greater in the exposed group
question
If the results of Odds ratio (OR) is < 1 it means what?
answer
The odds are less in the exposed group
