Systematic reviews and their application to research in speech and language therapy: a response to T. R. Pring's 'Ask a silly question: two decades of troublesome trials' (2004).

BACKGROUND

The advent of evidence-based healthcare has seen a rise in the use of systematic reviews to bring together the findings from research studies. The use of systematic reviews in speech and language therapy (SLT) was criticized in this journal in 2004 by T. R. Pring. It was claimed that their findings are misleading due to the potential inclusion of biased data, and uninformative due to a lack of detail in the reporting of interventions. It is argued that outcome research should be carried out in a series of phases in which small-scale research precedes large-scale research. This, it is argued, is most likely to demonstrate statistically significant effects and also help to ensure that therapies become sufficiently defined so that clinicians can apply them in practice.

AIMS

This paper argues that the above criticism of systematic reviews is based on a narrow conception of their capabilities: on the popular misapprehension that all systematic reviews answer effectiveness questions using only experimental studies and contain meta-analyses. Different methods for systematic reviews are described and their application within clinical outcome research is discussed with reference to a phased structure for empirical enquiry.

MAIN CONTRIBUTION

Systematic reviews seek to identify and synthesize information within a given topic area. They are used to answer a wide range of research questions and the studies they include are not limited exclusively to experimental designs. Methods of synthesis can include both statistical approaches, such as meta-analysis, and 'qualitative' approaches, such as meta-ethnography and thematic analysis. Knowledge of the current state of research is essential for a sequentially phased approach within outcome research to operate. Since systematic reviews are summaries of research activity, they can provide this knowledge and should therefore be considered a valuable tool within outcome research.

CONCLUSIONS

A systematic review using 'qualitative' and/or statistical methods for combining studies can be carried out within or across any of the phases within outcome research. Far from being uninformative, this can help bring together what is, and what is not, known and indicate the kinds of therapies that may be beneficial in the clinical setting and therapies which would benefit from further research and development.