The strong focus on positive results in abstracts may cause bias in systematic reviews: a case study on abstract reporting bias

ConclusionsThis case study on abstract reporting bias shows that (a) more than half of all relevant articles were missed by a conventional search query and (b) this led to an overestimation of the pooled effect. Detection of articles will be improved if all studied exposure and outcome variables are reported in the keywords. The restriction on the maximum number of keywords should be lifted.
Source: Systematic Reviews - Category: International Medicine & Public Health Source Type: research