Background: The importance of systematic reviews in identifying gaps in the evidence base and providing a quantitative basis for informing new research initiatives is widely acknowledged, but little is known about what actually happens in practice.

Objective: To assess the use made of results of reviews in the designing of new studies

Methods: Of all Cochrane reviews published in 1996, those updated in 2002 or 2003 were identified. Authors of trials added in the updates were contacted and asked if use had been made of the 1996 Cochrane or other reviews in designing their study.
Results: Of 32 authors of studies newly included in 33 Cochrane reviews which met our inclusion criteria, 24 (75%) responded. 11 (46%) respondents were aware of the relevant Cochrane review at the time they designed their study. In 8 (33%) cases the design of the new study had been influenced by a review; in 2 (8%) this was the relevant Cochrane review (see figure).

Conclusions: Cautious interpretation of these results is necessary, but it is apparent that the proportion of study investigators using Cochrane or other systematic reviews in designing their new studies was very limited. Inclusion of encouragement in publication or application guidelines to consider and cite review results is desirable.