[Guidelines and scientific research: the basis should be both evidence and a variety of considerations]

In evidence-based medicine, decisions about patient care are based on the results of sound clinical research. Yet, even in evidence-based medicine, science does not directly dictate practice. Making decisions requires setting priorities and making trade-offs. The results of scientific research limit rather than prescribe the available options. When a treatment is known to be ineffective, it cannot be selected for its efficacy. When a treatment has been shown to produce a particular effect, opting for that particular treatment should be based on the desirability of the demonstrated effect and trade-offs between that effect and other effects. Guidelines for clinical practice should reflect the results of clinical research, as well as the priorities that have been set and the trade-offs that have been made.