Chapter 4 Flashcards
(21 cards)
What are observational studies?
Researches observes & meausre but does not intervene. Results from these studies adress health-related conditions cause and can describe them.
Whatr are intervention studies?
Researchers activityly intervenes to change something in particepanst, to see what effect this has on one or more health-related conditions. These determine effective interventions for preventing and treating dieseaee
4 Key purposes of epidemiology are
Describe health-related outcome, determine the cuase of the health-related conditions, determine effective interventions for preventing and treating disease, use these results to impact public health
Randomised controlled trials for preventions
Randomise healthy people to differnet prevention arms to see if one reduces the risk of developing diesease more than another
RTC for treatment
Identify a group of patients with the same conditotn and then randomize them to either receive the treatment or to a control group that does not recive the treatment
Cross-over trials
In Cross-over trials particpants serve as their own control. I.E same poeople are observed twice under conditions that are identical expect to respect to the intervetion arms being compared
Community trails
They are cluster trials (i.e groups of people are randomized togetehr) in which the intervention is implemented at a community level. They are used when the intervention is better dilvered to large groups.
Cohort Studies (prospective/ longitudinal study)
researchers follow participants forward over time to see what happens to them. Living ht e lives they have chosen, and researchers measure exposures they have chosne for themselves
Case control studies
Draw back of cohort is can only be used to meausre diesase relatively common. For case contorl researchers start by requireting participants from study pops who develop disease of interest. They work backyards, have patients with exposure and measure how it gets better or worse
Cross sectional studies
Data from surveys that countries or ppl collect ca be used to look at the relastionship between behaviour & other exposure and health related outcomes.
Ecological studies
They compare the prevelance of exposure and occurance of the diease in populaitons or groups of people, not individuals
What is a challenge with cohort studies & other observational studies?
To disentangle the effects of the exposure we are interested in the other characteristics that are correlated with that exposure. They are also very time-consuming, expensive
What are 2 primary drawbacks from using case-control studies?
1) the issue of confounding variables
2) Selection bias, Participation rates are considerably lower in controls than cases. Refusal to take part in a lower is often related to health and lifestyle factors so controls who take part may not represent the wider population.
What are some problems with ecological studies?
They can be difficult to interpret.
- Temporal sequence is not clear
- Confounding
What is a draw back of cross-sectional studies?
You can not identify which came first - the exposure or the outcome (disease). The problem of reverse causality is a major issue in cross-sectional studies (does A really cause B or does B cause A?) also confounding factors
Example: Randomize a group of people at risk of developing T2D into usual care or intensive lifestyle (diet + exercise) groups. Determine if the intensive lifestyle interventions reduces the risk of developing T2D
Randomize control trial
Example: Study want to compare the effects of two protein supplements on muscle strength. 50% of the participants take Sup A an d 50% take Sup B for 4 weeks. Researchers measure the change in muscle strength over these 4 weeks. All participants switch and take the opposite protein supplement for 4 weeks.
Cross-over trail
Example: Studeis of water fluriodation and dental health. When investigators wanted to study the effects of adding fluoride to some peoples water and not to others within a given city. therefore, whole cities were allocated to receive fluoride in their water or not
Community trials
Measure the PA levels in a group of 10,000 participants who do not have heart disease. Follow-up the group over 10 years to determine which participants develop the disease.
Cohort studies (follow-ups over time)
Example: If we wanted to know whether smoking was associated with lung cancer, we could recruit cases and controls. We could ask the cases and controls questions to determine their lifetime history of smoking. We could then determine if smoking habits differed in the cases and controls
Case-control studies
