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
What are the 4 strengths of cohort studies?
- Large sample size
- Can be used to calculate incidence
- Can be used to examine multiple outcomes (rare and common, but better for common ones)
- Can be used to examine exposures (rare and common, but great for rare ones)
What are the 5 limitations of cohort studies?
- Expensive and time-consuming
- Loss of follow-up over time
- Inadvertent crossover with status changing over time (eg: smoker becoming a non-smoker)
- Self-selected populations that do not represent the pop as a whole
- Self-reporting on dietary questionnaires can be inaccurate
What does prophylactic mean?
Intended to prevent disease
What is a community trial? Are these still done?
Experimental study where a prophylactic or treatment intervention is given to an entire community and compared to a control community.
Not done anymore because of ethical issues
What is a metabolic study?
Participants are given the intervention in the lab and real time data is retrieved
Which type of study is the most data driven?
Metabolic studies
What is an intention-to-treat analysis?
Including “mistakes” in final analysis, but the inclusion of “anomalies/mistakes” is considered to be a more “real-life” approach to analyzing effects.
What are the 6 steps of the scientific method?
- Theory
- Hypothesis
- Experimentation
- Results
- Interpretation
- Conclusion
List the 6 study types used in nutrition in order of worst to best.
- Cross-sectional
- Case-control
- Cohort
- CTs
- Community
- Metabolic
