Week 12 - Content Flashcards
(23 cards)
When can an epidemiological study be used too establish causality?
If effect is very strong and no other explanation sufficiently accounts for the data.
What is a classic example of confusing correlation with causation?
Vaccines and autism
How are thalidomide and birth defects linked?
1950-60s thalidomide was used to treat morning sickness but then lots of babies were born with birth defects. Affect was so pronounced and no other variable could be found to account for impact thus causality was established.
What is Mea-analyses?
Put together many studies looking at similar thing to draw more robust conclusion.
What studies does correlation occur in?
Cohort, case-controlled, cross sectional.
What is a cohort study?
Type of longitudinal study, an approach is to follow participants over a period of time (many years).
-allows examination of many variables in people over time to observe relationships
-expensive and time-consuming to conduct, need to have large sample group
What is a case control study?
The of observational study, that analyses data from a population, or a representative subset a specific point in time.
- patients who have developed a disease are identified and their past exposure to suspected aetiological risk factors is compared to that of the controls who do not have disease. Permits estimation of risk factors.
What is a cross sectional study?
Measures prevalence of disease or determinants of health in a population.
What is a strength of clinical trials and biomedical studies?
Use controllable (or independant) variables in a well defined environment with defined measurements, to determine whether a variable is altering another variable.
What is the gold standard for clinical trials?
Randomised Double Blind Placebo Controlled Clinical Trial.
What occurs in the first phase of a clinical trial?
First in human, test safety, small numbers (10-50), often healthy subjects not disease (depending on factors)
What occurs in phase 2 of a clinical trial?
Further evaluated safety, determine efficacy (does it work), people with disease, several hundred patients.
What occurs in phase 3 of a clinical trial?
Does intervention work in larger group, plus more safety, people with disease, several hundred to several thousand patients
What is phase 4 of a clinical trials?
Happen after therapy is approved and sold on market, does not always happen, monitor effectiveness of it in general populations and any adverse affects associated with widespread use over longer periods of time, investigate use in different condition or in combination with other therapies.
Why are rarer side effects not always picked up in clinical trials?
Side effects can occur in long term, may only appear in phase 3 when sample group is large enough, drugs may not be used as prescribed, drug-to-drug interaction, occur in populations which may not have been included in trial.
What are Biomedical/Experimental studies?
Directly test for how something works or its ‘mechanism of action’
Determines whether causation is feasible and how it would occur.
What is an In Vitro study?
Cells in the lab relevant to the disease in question
What is an In Vivo study?
Usually with rodents using preclinical models of disease.
What is a strength of biomedical study vs clinical trials?
Much faster way to determine effect than clinical trials but it is only predictive, human clinical trials required to know
What is the importance of controls in Biomedical studies?
Specific to experimental question and design, must account for impact of variable itself
Designed for unbiased observation/measurement
What is a placebo?
Sham substance or treatment which is designed to have no known therapeutic value eg/sugar pills, saline injections and sham devices
What is the placebo effect?
Brain convinces your body that sham treatment is real thing, in some clinical trials >50% improvement have been observed.
How does the placebo effect work?
- Neurotransmitters, like endorphins and dopamine increased, make you feel better
2.greater activity in certain brain regions linked to emotional reactions leads to a therapeutic benefit
- may make you feel better, but won’t cure disease
