Diet And Cancer Flashcards
Which risk factors are linked to bowel cancer?
Obesity
Processed meats such as sausages and salami
High red meat consumption
Tobacco
Inactivity
High salt and alcohol consumption
What is the Bradford Hill criteria?
Used to establish the relationship between cause and effect for a hypothesis based on:
Strength of association
Temporality
Dose response
Modifiable
Plausible
Specificity
Coherence
What is the strength and association factor?
A greater odds ratio/relative risk indicates a greater causality.
What is the temporality factor?
The cause/risk should come before the effect/outcome.
What is the dose-response factor?
Outcome should be dependent on the level of the exposure.
What is the specificity factor?
A cause will have only one effect.
What is a confounding variable?
A cause and an effect are linked by a third factor.
What is reverse causality?
When the expected result is reversed and the effect leads to the cause, therefore it is important to establish temporality in a study.
What is a case control study?
Retrospective study based on outcome like disease where a group with the disease and a group without are compared for exposure to risk factor. It is measured using odds ratio.
How is a case control managed to increase validity?
Patients are matched for age and sex to prevent confounding.
Case control is good because it is fast and cheap and good for rare diseases. However, it is subject to recall bias, and difficult to measure the risk and the impact of risk.
What is cohort study?
Groups are selected based on their exposure to risk factors and they are observed to see if they develop the outcome, which can be retrospective or prospective and measured using relative risk. Patients are excluded if they have the outcome. It is useful for assessing a range of risks, however it is expensive and difficult to measure risk.
What is meta-analysis?
The statistical combination of the results from similar studies addressing a specific question into one pooled result in the form of a forest plot. It is the gold standard bias for the evidence hierarchy.
The studies should not have too much heterogenity, such as many differences like intervention or population which limits the comparison that can be made. However, it is subject to publication bias and needs periodical revision.
What is a systematic review?
Synthesis of the findings from multiple sources into one research paper.
What are the considerations for RCT trials?
Identify causal relationships and reduce confounding bias by controlling participant factors to measure effect of intervention. However, it is expensive and prone to generalisable.
What is the evidence hierarchy?
Meta-analyses is the gold standard, followed by systematic review.
RCTs are the best trial > Cohort > Case control > Case-series
