Unpublished data, data not recorded on or difficult to identify from electronic databases, and data of significant age are good examples. The Cochrane Library, which includes a database of controlled trials, may contain useful evidence but a preliminary search reveals no previously identified trials on aspects of nursing management of patients with chest drains. Evidence for practice which is descriptive or, if experimental, methodologically weak is a particular problem. The point of a systematic review is the application of objective criteria. Much of the data so far uncovered may not meet basic criteria as useful guidance for practice.
Careful consideration is needed.
Life as a systematic reviewer becomes much harder when evaluating evidence other than that found in controlled trials. Box 1 shows recommendations for further work in this area. YOU CAN HELP Many nurses feel that research is an exclusive activity, but this article shows how nurses can supply anecdotal evidence to develop protocols and guidelines. Of the evidence identified so far, much is contradictory or prescriptive rather than justified. There is great scope for RCTs to answer the nursing questions we have identified.