Academic Flashcards
What study reporting guidelines exist (6)?
CONSORT - RCT
IDEAL - Surgical Innovation
MOOSE - Meta-analysis of observational studies
PRISMA - systematic Reviews
STROBE - Observational studies
TRIPOD - Predictive models
What is a null hypothesis?
The initial hypothesis stating there are no differences between the items studied
What is the sensitivity?
Proportion of true positives correctly identified
Proportion of patients with a disease that test positive
What is Specificity?
Proportion of true negatives correctly identified
Proportion of patients without a disease that test negative
What is the absolute risk reduction?
The difference in event rates between two groups
The NNT is the inverse of this
What is a regression analysis?
A statistical means of establishing the dependence of a variable on one or more different variables.
Practically, regression analyses are often used to either generate predictive models or to establish the indepent effect of different variables
What is the variance and SD?
- Summary of variability of a dataset. SD is the square root of the variance.
- In normally distributed data, 68% of the data lies within 1 SD and 95% in 2 SD
- measure of the central tendancy of the sample
What is a confidence interval?
A measure of the precision of study estimates compared to population values
How can the quality of RCTs be assessed?
JADAD score
1) Was the study randomised
2) Was the study double blind
3) Was there a description of dropouts and withdrawals
4) Was the randomisation appropriate?
5) Was the blinding complete?
CONSORT guidelines
How is an impact factor defined?
IF 2021 = (total citations in 2021 for articles published in 2019+2020)/number of articles published in 2019+2020
What is a power calculation?
- Usually conducted a priori
- Calculation of sample size required to reach a specified power level (usually 80% chance of avoiding a type. 2 error)
- requires an expected effect size from previous work
What are the levels of evidence?
1a - SR/MA RCTs/ Consensus Guidelines
1b RCT
1c All or nothing trial
2a SR/MA Cohort studies
2b Individual Cohort studies
2c Outcome studies
3a SR/MA Case-control
3b Case-control
4 Case series
5 Expert opinions
What is the GRADE recommendations?
A - Level 1 studies, or consistent 2a/2b/3 studies
B - generally consistent findings from Level 2/3 studies
C - inconsistent findings from Level2/3 studies
D - no systematic evidence
GP - good practice guidelines
What is a RCT?
Level 1b evidence where patients are randomised to different treatments and outcomes compared
Pros
- Provide strong evidence of cause and effect
- randomisation minimises most types of bias that affect other studies
- blinding reduces observer bias
Cons
- Time consuming and expensive
- can lack equipoise
- analysis of subgroups difficult
- require long follow up period
What is a cohort study?
Group of patients identified for study without reference to an outcome. Can be prospective or retrospective
Pros
- Can study multiple outcomes
- Good for rare exposures
- Can measure incidence
- May infer causality
Cons
- Bias increased (particularly for retrospective)
- Confounding variables inevitable
- Loss to follow up
- Not useful for rare outcomes