Methodology for constructing guidance.

Although guidance exists for the use of many laboratory tests in a wide range of clinical situations, this guidance is spread among a range of literature sources, and is often directed at laboratory specialists rather than test users. Individual general practices display large variations in standardised test requesting, yet much of their testing activity involves a relatively small range of tests. This paper describes a methodological approach to review the available evidence and guidance and to extract relevant primary research work to examine a range of testing scenarios in general practice, with the aim of formulating guidance based on the best available evidence or consensus opinions.