Systematic reviews, meta-analysis and meta-synthesis

Meta-synthesis

- "bringing together" of qualitative data - the evidence for an interpretation is strengthened by discovering common themes and differences and building new interpretations of the topic of interest. - a way of developing new theory

Systematic reviews

- a comprehensive, reproducible search for primary studies on a focused clinical question. - selection of studies using clear and transparent eligibility criteria - critical appraisal of studies for quality

Integrated reviews

- can include RCT, case study, qualitative study, mixed method study. - these studies are compared, themes are identified , analysed and gaps noted.

Why perform a meta-analysis?

- detecting a real effect as statistically significant if it exists. many individual studies are too small to detect small effects, but when several are combined there is a higher chance of detecting an effect. - the estimation of an intervention effect can be improved when it is based on more information. - consistency of effect and allow reasons for differences between studies. - opportunity to settle controversies arising from conflicting studies or to generate new hypotheses.

What do systematic reviews achieve?

- refinement and reduction - efficiency: quicker and cheaper to perform than a new study - results can often be generalised to a wider population in a broader setting - individual articles may offer little insight into the problem, but articles 'pooled' together may result in clearer and more consistent picture - any inconsistencies can be determined - aims to reduce errors: improve reliability and accuracy of recommendation

Meta-analyses

- statistical pooling of results from several studies to generate a summary estimate of effects. - produce a graph depicting the estimated effect in each trial and their average.

Difference between a systematic review and a meta-analysis

- systematic review: answers defined research question by collecting and summarising all empirical evidence that fits pre-specified eligibility criteria. - meta-analysis: the use of statistical methods to summarise the results of these studies.

Three types of meta-synthesis

Theory building - brings together findings on a theoretical level to build a tentative theory. Theory explication - a way of conceptualising the original phenomenon. Descriptive - provides a broad description of the research phenomenon.