A group of collaborating authors who review the literature of the effects of health care, using explicitly defined procedures in order to reduce the effects of bias in the reviews. The groups are expected to develop the reviews and to maintain them, i.e., to keep abreast of the literature and to modify the reviews as new information warrants. Input from the users of the reviews is sought, and the authoring review group is expected to respond to such input, including publishing the inputs and the responses to them. The reviews are published in the Cochrane Database of Systematic Reviews, issued several times each year.