Conducting a high quality systematic review can be time consuming and costly, with conservative estimates of more than 1000 person-hours for an average review. One important, but time consuming, step is the selection of studies for inclusion in the review. This is done by firstly applying the study eligibility criteria to citations retrieved from the searches. However, there is little evidence to guide review teams in choosing the most effective method for screening citations.
To evaluate the effects of two different methods of screening citations for inclusion of papers in a systematic review.
A two-group randomized trial. A database of 1072 citations was divided randomly into two groups i.e. (1) a single or a (2) two-stage method of citation screening. In the single-stage method, the title and the abstract were made available simultaneously, while in the two-stage approach the citation was screened by title only (stage 1) and then by screening the records judged to be potentially eligible using the title and abstract (stage 2). Two authors screened each citation independently.
The average time taken, across both reviewers to screen 100 citations was 120 minutes using the one-stage process compared with 170 minutes using the two-stage process. There was a significantly higher rate of rejection associated with the one-stage process (76.9%) compared with the two-stage process (66.2%) (RR 1.16, 95% CI 1.08 to 1.25). Inter-observer levels of agreement between both reviewers were moderate across all stages (kappa 0.41 to 0.57).
Screening using a method in which titles and abstracts are presented simultaneously is less time consuming than a two-stage process of presenting the title followed by the abstract.