NURS 7220-OL: Evidence-Based Practice/Informatics

A Meta-Anayslsis 

A meta-analysis goes beyond critique and integration and conducts secondary statistical analyses on the outcomes of similar studies.  It is a systematic review that uses quantitative methods to synthesize and summarize the results.

An advantage of a meta-analysis is the ability to be completely objective in evaluating research findings.  Not all topics, however, have sufficient research evidence to allow a meta-analysis to be conducted.  In that case, an integrative review is an appropriate strategy.  

A meta-analysis may be part of a systematic review.

Meta-synthesis 

What is a meta-synthesis?

First of all, what is a meta-synthesis? According to Screiber et al. (1997, p.314), a meta-synthesis “is bringing together and breaking down of findings, examining them, discovering essential features and, in some way , combining phenomena into a transformed whole” In basic terms, a meta-synthesis is the ‘bringing together’ of Qualitative data to form a new interpretation of the research field.

Meta-synthesis Vs. Meta-analysis: Whats the difference?

Unlike a meta-analysis which is used to aggregate findings to establish ‘truths’, for example, if an intervention has a true effect on a variable, a meta-synthesis can lead to new interpretations of research. This can result in new theories being developed.

In summary, a meta-analysis is a way of testing a hypothesis whereas a meta-synthesis is a way of developing a new theory.

Three main types of Meta-synthesis

1) Theory Building – This form of meta-synthesis brings together findings on a theoretical level to build a tentative theory.

2) Theory Explication – This form of meta-synthesis is a way of reconceptualising the original phenomenon.

3) Descriptive – This form of meta-synthesis provides a broad description of the research phenomenon.

These forms of meta-synthesis are not discrete, they are complimentary. The aim of Meta-synthesis usually overlap as you will see in the example later on.

Why use a meta-synthesis?

Qualitative data is useful for providing a snapshot at one person’s interpretation of an event or phenomenon. By bringing together many different interpretations you are strengthening the evidence for an interpretation by discovering common themes and differences & building new interpretations of the topic of interest.

Downe, S., Simpson, L., & Trafford, K. (2007). Expert intrapartum maternity care: a meta-synthesis. Journal of Advanced Nursing, 57(2): 127-40.

Literature Reviews

• summaries of relevant literature
• generally descriptive
• not necessarily any analysis of the literature
• methodology of the literature search is not always given
• good for gaining background knowledge of a subject without having to do all the searches and reading yourself.
• good source for starting reading lists and literature searches.
• not generally considered a good source for clinical decision making
• Note: In the past, reviews were not differentiated by type, so older reviews may use systematic or integrative methodology but not be specified as such.
• Reading: Ten simple rules for writing a literature review (Pautasso, M. (2013). PLoS Comput Biol, 9(7), e1003149.)

Integrative Reviews 

• commonly include non-experimental research, such as case studies, observational studies, and meta-analyses, but may also include practice applications, theory, and guidelines (Systematic reviews include only quantitative, experimental studies, and many times only randomized controlled trials.)
• should have clear and precise search and selection criteria
• search and selection methodology should be described well enough for another researcher to duplicate the process
• selected literature should be analyzed, not just summarized--articles and groups of articles compared, themes identified, gaps noted, etc.
• Reading: The integrative review: updated methodology (Whittemore & Knaf, 2005, Journal of Advanced Nursing, 52(5), 546–553) provides an overview of the purpose and practice of integrative reviews.

Systematic Reviews

• specifically include experimental research studies
• search and selection methodology is very precise and should be explicitly described well enough for another researcher to duplicate the searches and the study selection. See Table 1 of this article (Hoojimans et al, 2012. PLoS One, 7(11): e48811) for a good example of describing the search methods.
• the purpose of a systematic review is to reach some conclusion regarding the topic: for example, the selection of high quality studies to be used in a meta-analysis*, the gaps in current research, or the best clinical evidence for determining evidence based practice.
• the first stage of meta-analysis studies--all meta-analyses should include a systematic review, but all systematic reviews do not lead to a meta-analysis
• Reading: A practical guide to conducting a systematic review (Forward & Hobby, 2002, Nursing Times, 98(2), 36) provides some basic advice for conducting a systematic review.