leren Flashcards
Name four types of reviews
Narrative/traditional reviews, critical reviews, scoping reviews, systematic reviews
What are narrative reviews?
These provide a general overview of the literature. Usually there is no specific research questions and it often had diverse/multiple aims and purposes. Different types of studies/literature are taken into account, but often there is no aim to be comprehensive in selection of included studies. Weighting of the studies is not transparent, and the selection of studies is potentially biased.
What are critical reviews?
They aim to demonstrate that the writer has extensively researched literature and critically evaluated its quality. It goes beyond a mere description and includes some degree of analysis and conceptual innovation. It typically results in a hypothesis or a model. It seeks to identify the most significant items in the field and the conceptual contribution to embody existing or derive a new theory. Analyses are typically narrative.
What are scoping reviews?
They are a preliminary assessment of the potential size and scope of available research literature. They aim to identify the nature and the extent of research evidence. The completeness of searching is determined by the time/scope constraints. They may include research in progress. There is no formal quality assessment of the included studies and the analyses are typically tabular with some narrative commentary. It characterises quantity and quality of literature.
What are systematic reviews?
They depart from a specific research question and are a systematic search for research evidence, often adhering to guidelines on the conduct of a review. An effort is made to include all the literature on a topic. There is a quality assessment that might determine inclusion/exclusion of studies. Analyses are typically tabular and if possible, a meta-analysis is included. They give recommendations for clinical practice and future research. Systematic overviews that are periodically updated seems like a good idea.
What are the four goals of Cochrane?
- Producing evidence;
- Making the evidence accessible;
- Advocating for evidence;
- Building an effective and sustainable organisation.
What are the six steps in performing systematic reviews?
- make up a research questions;
- search and select literature;
- asses the risk of bias of the studies included;
- extract data;
- analyse data;
- conclude
What steps does searching and selecting literature in systematic reviewing include? name 6.
a. Scoping you search topic;
b. Choosing the resources to search;
c. Choosing the search terms;
d. Compiling your search strategy and running the search;
e. Finding the full text;
f. Managing the information found.
What things should be thought about when making up a research question in a systematic review?
A systematic review should always depart from a clinically relevant and well-defined research question. As a guideline, PICO can be applied. However, there are other important things to think about, such as the timing of the outcome measures, design of studies, the time from when you include the studies and the language.
While analysing data in systematic reviews, comparisons must be defined based on…?
clinical homogeneity
What is clinical homogeneity?
the subgroups in each study should be the same, just as the interventions/controls and the outcome measures
What are sensitivity analyses for?
Sensitivity analyses are used to look at the differences of studies with a high risk of bias and low RoB.
How is the Cochrane method for quality assessment called? And what steps (4) does is include?
The Cochrane uses the GRADE method for quality assessment, which takes into account:
- Risk of Bias (risk of bias of the included studies/RCTs);
- Inconsistency (are the results of the included in the ‘same’ direction (so no inconsistent pattern));
- Indirectness (did the studies really include the target population and were the ‘real’ outcomes measured (not proxy measures));
- Precision (were enough people included in the analyses).
What is duplicate publication bias?
Duplicate (multiple) publication bias occurs when a study is counted more than once, as it is published in multiple papers. It also occurs when the first paper includes 50 patients and the second one 100. Then, only the second one needs to be included, as the result of the first paper will be exaggerated.
What is the salami tactic?
In here, different parts of a report are published in different papers. For example, in one paper the physical outcomes are published, in the other only the psychosocial. Or, in the first paper only the 1-year results and in a second paper the 3-year results.
What is the advanced salami tactic?
The advanced Salami tactic is when other authors (or in a different order) are in different papers on the same study.
What is location bias?
Trials published in low- or non-impact factor journals were more likely to report significant results than those published in high-impact, mainstream medical journals and the quality of the trials was also associated with the journal of publication. This refers to location bias: should you include all journals?
What is location bias?
Trials published in low- or non-impact factor journals were more likely to report significant results than those published in high-impact, mainstream medical journals and the quality of the trials was also associated with the journal of publication. This refers to location bias: should you include all journals?
What is language bias?
Language bias refers to bias that could be introduced in reviews exclusively based in English-language reports. However, the research examining this issue is conflicting.
Name four reasons meta analyses are performed
MA are performed, to:
- Increase the power/improve precision. Many individual studies are too small, thus combining yields a higher chance of detecting an effect;
- Answer questions not posed by individual studies. This increases generalisability/robustness;
- Settle controversies in apparently conflicting studies;
- Generate new hypotheses.
In the case of dichotomous outcome, in what two ways can the pooled average be measured?
- Absolute measures. This includes the risk difference (RD) and number needed to treat (NNT = 1/RD);
- Relative measures. This includes the risk ratio (RR) or the odds ratio (OR).
In what two ways can continuous outcomes be pooled?
Continuous outcomes can be measured in a numerical scale in two ways:
- Identical outcome measure with an identical scale.
- The same construct on a different scale (standardised mean difference). This is a correction for differences in direction of scale, as they must go in the same direction. The standard deviation does not have to be modified.
In what two ways can ordinal outcomes be pooled?
For ordinal outcomes, there are two solutions:
- Dichotomise;
- Continuous, when there are too many categories (>7?).
What three forms of heterogeneity exist?
clinical heterogeneity, methodological heterogeneity and statistical heterogeneity (heterogeneity)