Literature reviews: evolution of a research methodology.

Literature reviews summarise all past research efforts, and because of this, are increasingly being used as a way of addressing the rapid accumulation of health care information. Because reviews, rather than primary research, are now being used as the basis for many health care decisions, it is important that they are conducted with the same rigour of the primary research. To ensure this rigour, the past two decades have seen a progressive evolution in review methodology, to the point where reviews are now considered research in their own right. Despite this development, the standard of many published reviews remains poor. This paper summarises the development of the literature review methodology and discusses some of the implications for nursing.