October 9 Flashcards
There is evidence of confounding if the M-H is ____ less than the crude OR
10%
When making clinical decisions, what resources should be used?
-best available summaries of evidence -systematic review in which reviewers have gathered studies and possibly combined results in a meta analysis
What is the definition of a systematic review according to the Cochrane handbook?
A systematic review attempts to collate all empirical evidence that fits pre-specified eligibility criteria in order to answer a specific research question. It uses explicit, systematic methods that are selected with a view to minimizing bias, thus providing more reliable findings from which conclusions can be drawn and decisions made.
When are systematic reviews used?
-clinical decision making: inform decision making/advise patients -practice guidelines: medical societies/ministry of health putting out recommendations for clinicians to follow -cost-effectiveness analyses
What is a narrative review?
-abstract contains: clear condition they are looking into, outline the assessments for the condition, talk about the most used/standard treatment, other treatment options -gives an overview of everything related to the condition -informative but is broad -doesn’t have a system to follow -helpful to understanding information about the condition
What is a systematic review?
-abstract contains: specific objective, design, outcome measures, methods (specific, systematic, and reported in standardized way), results (presented as effect estimates) -focused question (for example, which treatment is better)
What are differences between a narrative and systematic review?
- narrative review can choose to leave things out or keep things in
- uncommon to see in a narrative review the appraisal of methods
- systematic reviews are reproducable but narrative reviews can’t be reproduced
What questions can systematic reviews address?
- interventions (eg. What are the effects of hip protectors in older adults living in institutions?)
- diagnosis (eg. What is the accuracy of the pap smear to diagnose CIN-2+?)
- prognosis (eg. What is the association between age and mortality in patients with acute myeloid leukemia?)
- incidence/prevalence (eg. What is the risk of complications after influenza vaccination?)
What steps are taken during literature search?
- decide on information sources
- identify titles and abstracts from literature
- aims: to find all of the studies, minimize chance of missing anything to make sure all relevant evidence is included and not a select group of studies
What types of sources can be searched during a literature search?
- large databases: Medline, CENTRAL, Embase, etc. to find all of the studies
- special databases: LILACs, PSYCHinfo, etc.
- trial registries: when researchers are conducting RCT they have to register it; see if someone is running a relevant trial that should have been published but it’s not (could say something about the trial itself), see if there are ongoing trials to acknowledge it in the review
- references in other articles
- contact experts in the field
How are studies selected?
- Examine titles and abstracts to remove obviously irrelevant reports
- Retrieve full texts of the potentially relevant results
- Examine full-text reports for compliance with eligibility criteria
- done by 2 independent reviewers to minimize errors
What happens during data abstraction?
- take each study and pick all of the things we are going to use from that study
- main characteristics about P, I, C, O, T
- abstract the outcome data
- risk of bias assessment (try to examine the extent to which the results of each of the studies are trustworthy)
What happens during conduction of analysis?
-synthesize the effects of the intervention based on the outcome level (job of systematic reviewer is to say what is the effect on the outcome of pain or the outcome of swelling, etc.)
What is the difference between a meta-analysis and a systematic review?
- aim of systematic review: aims to summarize all available evidence; synoptic and unbiased view of the available evidence
- meta analysis: statistical technique which allows for calculation of a single summary estimate synthesizing all available evidence for particular clinical question
- dots represent point estimates then lines are confidence intervals
- diamond on the bottom represents point estimate and confidence interval of all of them
- not all data can be included in a meta analysis
Assessing quality of evidence
