Informed consent in biomedical studies on aging: survey of four journals: Table 1

ration.This exercise will help identify randomised controlled trials for health care decision making, and in particular will help the Cochrane Collaboration to pre- pare, maintain, and disseminate systematic reviews.We thank the staff of the Baltimore Cochrane Center, librar- ies in the Oxford region, Iain Chalmers for his comments on the manuscript, and all the handsearchers.