Lecture 13: Nutrition Epidemiology & Research Flashcards
What are observational studies important for? 3 things
- Monitoring health and disease in pops
- Finding associations that should then be tested in controlled trials
- Assessing risks of therapies
Can observational studies prove the efficacy of a therapy?
NOPE
What are the 3 limitations of observational studies?
- Selection bias
- Adherence bias
- Healthy user bias
What is a clinical impression?
Non-comparable data based on observation of a patient’s presentation and the practitioner’s judgment of the issue = LEAST RELIABLE
What is a cross-sectional survey?
Observational study that involves the analysis of data collected from a pop that assesses exposure and outcomes at the SAME time
What are 2 other names for cross-sectional surveys?
- Prevalence studies
2. Frequency studies
What are the 2 strengths of a cross-sectional survey?
- Large pop size shows a stable average diet
2. Reveals contrasts in dietary intake in large pops
What are the 4 limitations of cross-sectional surveys?
- Correlation is NOT causation
- Potential determinants of a disease can vary
- Food disappearance: data uses food produced and sold, NOT food consumed
- Data cannot be independently reproduced
Do cross-sectional studies assess prevalence or incidence? What is the difference?
They assess prevalence = how many patients have a certain outcome, not incidence = the rate over time of the outcome occuring
What is a case-control study?
Observational study that has controlled/comparative data on patients who have a disease and patients who don’t and looks back retrospectively
What are 2 strengths of case-control studies?
- Best for testing rare and new diseases and adverse drug reactions when variable is clear cut
- Obtaining data is easy and targeted
What are 4 limitations of case-control studies?
- Small pop size (hard to have statistical significance)
- Hard to select an appropriate control group
- Easy for methodologic bias to skew data
- Easy for confounding to happen
What is a cohort study?
Observational study that has controlled/comparative data: longitudinal studies in which an exposure is assessed and participants are followed prospectively to observe the outcome
Which type of study is the most popular for nutrition knowledge?
Cohort studies
Why can cohort studies be considered ambidirectional?
Because they can retrospectively assess participants and then prospectively throughout the study