Evidence-based medicine and other Flashcards
What are the types of observational studies?
- case-control study
- cohort study
- cross-sectional study
What is the positive of observational studies?
they don’t involve interventions so are safer than RCTs
What are the features of case-control studies?
- backwards direction of research enquiry so look at past risk factor and calculate odds of getting disease
- people selected first then their risk factor is measured
What is the bias in case-control studies?
- selection
- observer (knowledge of whether they are case or control)
- recall (cases will be better)
- survivor (high fatality diseases = big bias)
What is confounding?
when another variable is driving the outcome more than the one being studied
What are the positives and negatives of case-control studies?
+rapid and cheap
+good for rare diseases
-bias
-incidence rates can’t be done as you are choosing patients with the disease
What are the features of cohort studies?
- good for infrequent exposure
- disease incidence can be measures as people don’t start with disease
- risk can be monitored over time
What can be calculated from cohort studies?
the relative risk ratio can be used to work out hot many times higher the risk of developing the disease is when a patient has a risk factor
What are the two types of cohort study?
- prospective: follow-up into future but is time-consuming and expensive
- retrospective: looks back to a point, cohort is established because they have a disease which is cheaper and faster
What are cohort studies not good for?
rare diseases
What are the biases present in cohort studies?
- selection
- information
- confounding
What are the features of a cross-sectional study?
- specific point in time
- survey
- quick and cheap
What P value causes the null hypothesis to be rejected?
P<0.05 means there is less than a 5% chance that the result is due to change so the null hypothesis is rejected
What do adipocytes secrete?
cytokines which then attract macrophages which infiltrate adipose tissue
What does obesity predispose to?
inflammation at the ER can’t cope with the metabolic demands
What does Orlistat do?
inhibits the action of lipase so fat is not absorbed in the gut
What are the types of bariatric surgery?
- gastric band= restrictive, simplest surgically, not the best outcomes
- Roux-en-Y gastric bypass= both restrictive and malabsorptive, bypasses stomach and a lot of the duodenum
- vertical sleeve gastrectomy= restrictive, stomach is smaller
What is the RMR?
the resting metabolic rate is the baseline calories burnt by being alive (contributed to by fat mass and fat-free mass)
What changes the RMR?
it will lower more in response to weight loss which is also known as adaptive thermogenesis
When can a patient not consent for themselves?
- lost capacity
- severe mental health issues
- limited capacity due to age
What can the thyroid be imaged with?
CT and US or nuclear medicine
What can the pituitary gland by imaged with?
MRI
What are the features of a thyroid US?
- safe
- no radiation
- well tolerated
When is a thyroid US used?
euthyroid with palpable nodules and hyperthyroid with focal masses
