EBD Flashcards
What is the formula for risk?
no. of events of interest/total number of observations
What is the formula for odds?
no. of events of interest/no. without the event
What is the formula for odds?
no. of events of interest/no. without the event
Difference between relative risk vs absolute risk reduction?
relative risk - reduction between 2 events in percentage
absolute risk is the difference in percents by subtraction
How do you figure out the relative/absolute risk?
using a 2x2 contingency table
What is the value of no difference for the absolute risk difference?
0
What is the value of no difference for the absolute risk difference?
0
What is the number needed to treat? How do you work it out?
What is the value of no difference for risk ratio (relative risk)?
1
Why might you have a wide confidence interval?
small population size
Pyramid of evidence
What are cohort studies good for?
Incidences of disease
Measures exposires and follows people over time
Design elements of RCTs?
-inclusion/exclusion criteria
-control/comparison groups
-randomisation
-blinding/masking
Which part of randomised control trial design minimises bias and how?
-randomisation of participants to groups = prevents researchers from influencing which participants go into each group (might put certain people in groups so that the drug/intervention looks better)
-blinding/masking of participant nad researcher (prevents maniupulation of results and assessment of the groups)
Which part of randomised control trial design minimises bias and how?
-randomisation of participants to groups = prevents researchers from influencing which participants go into each group (might put certain people in groups so that the drug/intervention looks better)
-blinding/masking of participant nad researcher (prevents maniupulation of results and assessment of the groups)
How can you check trial quality?
Using the Consolidation of the Standards of Reporting Trials publication (CONSORT)
Can also use CASP tool (critical appraisal skills programme)
How do you assess if a RCT results are valid?
-Did the trial address a clearly focused issue (PICO)
-was assignment randomised?
-were all of the patients who entered the trial accounted for at its conclusion?
-was it blinded/masked
-were the groups similar at the start of the trial
-were the groups treated equally apart from the intervention
Benefits of systematic revies over single studues?
-saves readers time
-provide reliable evidence (unbiased comprehensive picture of body of evidence)
-resolve inconsistencies
-identify gaps (where good studies are not available)
-identify when Q’s have not been fully answered
-explore differencies between studies
What are the key characteristics of a systematic review?
-well formulated Q (PICO)
-comprehensive data search
-unbiased selection and abstraction process
-assessment of papers
-synthesis of data
What are the key characteristics of a systematic review?
-well formulated Q (PICO)
-comprehensive data search
-unbiased selection and abstraction process
-assessment of papers
-synthesis of data
What is reporting bias?
-positive results are more likely to be pubished, published more rapidly, in English and more likely to be cited as this is what sells
When doing systematic reviews need to look at unpublished data too
Why does the risk of bias need to be calculated?
because it determines the extent to which results of a study can be believed
Why does the risk of bias need to be calculated?
because it determines the extent to which results of a study can be believed
bias can overestimate or underestimate the effect
