Abstract
Many Guidelines and Consensus Statements were published in 1993 and 1994. The pressure to produce these guidelines comes from clinicians faced with rapid change, from a wish to provide an independent authoritative view rather than rely on commercial promotion of particular treatments, and from governments seeking assistance with the allocation of scarce resources. Evaluation of the impact that guidelines exert on clinical practice is notoriously difficult, but has been attempted using the self-report questionnaire, or the more reliable but expensive analysis of actual practice data, before and after publication of the guidelines. Rigorous evaluation has been attempted and reported in North America and in Europe, in relation to surgical and obstetrical procedures and psychiatric disorders as well as medical treatments. Specific evaluation of the impact of recommendations from the Joint National Committee in the USA, for the treatment of hypertension, has also been attempted, as well as surveys of doctors' perceptions of Consensus Statements. The evidence available suggests that the main value obtained from Guidelines and Consensus Statements lies in their capacity to codify good or "best practice", at times of rapid change in a particular field. They also serve as a source of support for local opinion leaders, and as they are usually produced by respected authors they have substantial influence with Government. Guidelines are not effective in producing rapid change in clinical practice. If a change in practice is sought a more comprehensive program of action is necessary, with guidelines as one useful element.