LECTURE 6 (Problems with studying humans) Flashcards
What is the ultimate goal of epidemiological studies?
To determine the causes of disease
How do you determine the causes of disease?
1) Observing a possible association between an exposure and an illness
2) Developing a hypothesis about a cause-and-effect relationship
3) Testing the hypothesis through a formal epidemiological study
Studies of which diseases are especially prone to error?
Chronic diseases
What is the most rigorous form of intervention study?
The randomised controlled trial
How do you conduct a randomised controlled trial?
1) Researchers choose a normal group of people and divide them randomly into an experimental group and will instruct them to do certain things (e.g eat a strict low-fat diet) for the next 5 years
2) A control group will be told to do the same things
3) Researchers will monitor both groups, watching for signs (e.g of heart disease) and will justify their hypothesis
What are the limitations in the randomised controlled trial?
- It is impossible to control the behaviour of human beings under such circumstances
- People will lose motivation (unless it’s the only chance to live)
- People may not do it for the necessary length of time
- People might become concerned with their health and stop
How do you conduct a Cohort study?
1) Choose a large group of people who are free of heart disease and ask them detailed questions about their diets etc
2) Over the next five years, compare the health of those who already eat a low-fat diet and those who eat an average diet
What are the advantages and disadvantages of a Cohort study?
ADVANTAGES
- does not require people to change their behaviour
DISADVANTAGES
- correlation doesn’t 100% mean cause because other aspects could be the reason (e.g those with low-fat diet could also exercise more, not smoke)
How do you conduct a Case-control study?
1) Researchers choose a group of people who already have the disease
2) A comparable group of people who do not have the disease would serve as the control group
3) Researchers would question both groups on the past 5 years and decide whether the correlation supports the hypothesis
What are the problems of Case-control study?
- Research information may not be reliable
- People may not remember what they did in the past 5 years
- People might be embarrassed to admit things
- Controls may be different in ways researchers may not have anticipated or be hard to account for in comparison
What do conflicting published reports result in?
Making people distrustful of the news and uncertain about how to protect their health
What are the main sources of error?
- There is a random variation and the association is merely due to chance
[can be counteracted by using large numbers to draw valid conclusions] - Long periods may pass between exposure and development of illness -> difficult to draw conclusions
- Cause-and-effect relationship is not obvious
The ________ the relationship between exposure and disease, the larger the group that must be studied to clarify the relationship
Weaker
What are Confounding variables?
Factors associated with the exposure that may independently affect the risk of developing the disease
(e.g smoking)
How can you avoid possible sources of error?
- Well-designed studies
- Large number of participants
What is Bias?
The influence of irrelevant or even spurious factors or associations
How can selection bias arise?
When the control group is insufficiently similar to the treatment group
What is Syphilis?
A sexual transmitted disease that had an unpredictable course. It was sometimes treated with an arsenic-containing drug called Salvarsan.
SYMPTOMS:
- blindness
- heart disease
- dementia
- paralysis
HISTORY:
some scientists suspected that the treatment was worse than the disease. This conclusion was supported by a Norwegian study of untreated syphilis in the early 20th century -> 75% of patients were symptom-free 20 years after the disease
Describe the Tuskegee syphilis study
In 1932, US Public Health Service and scientist from Tuskegee Institute took 400 black men and told them they had “bad blood” and were enticed to participate with “free treatments” and physical examinations, free hot lunches and free burials but were given syphilis. They were not given penicillin until 1972, when the story broke out.
Where did the Tuskegee Syphilis study take place?
Macon county, Alabama
What year did the Tuskegee syphilis study take place?
1932
What were the ethical issues of the syphilis study?
- The men were deceived
[not told about syphilis or the study an lead to believe they were receiving treatment] - One test was a SPINAL TAP (a painful procedure to withdraw spinal fluid) -> can cause paralysis
What was the purpose of the Tuskegee Syphilis Study?
To observe the course of the disease in the men, who were not to receive treatment
Which study lead to the establishment of rules for the conduct of human experimentation?
Tuskegee study
Which rules must institutions follow to receive federal funds?
- Every research subject must be informed of the purpose of a study and its risks and benefits
- Subject must freely consent to participate
- Study must be approved in advance by INSTITUTIONAL REVIEW BOARD (IRB)
- Clinical trials halted if treatment group is clearly showing better or worse results than control group
What is the Institutional Review Board (IRB)?
A committee that includes representatives of the community as well as other scientists who agree and control the study protocol
What do the Institutional Review Board (IRB) regulate?
- If the study is well designed
- If its benefits outweigh the risks
- If the subjects are truly given the opportunity for informed consent
What are the ethical principles that apply to epidemiological research?
- Respect for the person = treating people with dignity and respecting their autonomy, privacy and confidentiality
- Beneficence = maximise benefits and minimise potential harms
- Non-maleficence = do no harm
- Justice = benefits and burdens of research distributed fairly and equitably across populations
