A comparison of two search methods for determining the scope of systematic reviews

Article type
Forsetlund L1, Kirkehei I1, Harboe I1, Odgaard-Jensen J1
1Norwegian Knowledge Centre for the Health Services, Norway
Background: One of the core activities of the Norwegian Knowledge Centre for the Health Services is the summary of research literature into systematic reviews on request. A pilot search to assess the scope of a new review is conducted before starting the reviewing process. These searches are conducted in pre-specified databases. However, new search facilities are sometimes launched, which challenge previous search methods.

Objectives: To develop a pragmatic approach for systematically comparing two search methods for determining the scope of a systematic review. The first method (Direct Search Method) included performing direct searches in the Cochrane Database of Systematic Reviews (CDSR), Database of Abstracts of Reviews of Effects (DARE) and the Health Technology Assessments (HTA). Using the comparison method (NHS Search Engine) we performed searches via the search engine of the British National Health System, NHS Evidence.

Methods: We used an adapted cross-over design with a random allocation of the 55 requests for systematic reviews. The main analyses were based on repeated measurements adjusted for the order in which the searches were conducted.

Results: The Direct Search Method generated on average fewer hits, 48% (95% CI 6% to 72%), had a higher precision, 0.22 (95% CI 0.13 to 0.30), and more unique hits than when searching by means of the NHS Search Engine, 50% (95% CI 7% to 110%). On the other hand, the Direct Search Method took longer, 14.58 minutes (95% CI 7.20 to 21.97), and was perceived as somewhat less user-friendly than the NHS Search Engine, 0.60 (95% CI 1.11 to 0.09).

Conclusions: Although the Direct Search Method had some drawbacks such as being more time-consuming and less user-friendly, it generated more unique hits than the NHS Search Engine, retrieved on average fewer references and fewer irrelevant results.