Clinical trials and research Flashcards
What is at the bottom of study designs?
editorials and expert opinions
What are case reports?
individual reports usually published by doctors or 1 or more patients w a condition who are found to respond to a particular treatment
Why are case reports not regarded as strong scientific evidence?
anecdotal nature
lack of control groups
what are case controlled studies?
cases of people with a condition are compared with similar cases who don’t
What are cohort studies?
comparing large groups or its w or w/o a condition over time
Why don’t case-controlled and cohort studies have strong evidence/
show correlation or association but not causation
What are RCTs?
similar patients are randomly assigned to an intervention or control group to study the effect of the intervention
What are benefits of RCT
low risk of bias and confounding
can infer causality
What are disadvantages of RCTs?
time consuming
expensive
unrepresentative study population
what are benefits of case-controlled studies?
quick - as outcome has already happened
Good for rare outcomes
What are disadvantages of case-controlled studies?
difficult finding appropriately matched controls
prone to selection and information bias
What are cross-sectional studies?
Observational study collecting data from a population and a specific point in time
snapshot of a group e.g. census or patient survery
What are benefits of cross sectional studies?
😍 Large sample size
😍 Provides data on prevalence
What is a disadvantage of cross sectional studies?
Risk of reverse causality- which came first?
What are cohort studies?
Longitudinal study in similar groups but with different risk factors/treatments. Follows them up over time
What are benefits of cohorts?
😍 Can follow up rare exposure e.g. natural disaster
😍 Allow identification of risk factors (exposure causing outcome)
What is a disadvantage of cohorts?
Takes a long time, people drop out
What are critical appraisals?
looking at the validity, the reliability and the applicability of someone’s research.
What are systematic reviews?
clearly formulated question, comprehensive search strategies, explicit inclusion/exclusion criteria.
What is the p value?
the probability of obtaining the test statistic from the data, assuming that the null hypothesis is true.
What does it mean if the P value is <0.05
statistically significant, reject H0.
What does it mean if the P value is >0.05
not statistically significant, insufficient evidence to reject H0.
What type of error are false positives?
1
What type of error are false negatives?
2
