To compare the effectiveness of systematic review literature searches that use either generic or specific terms for health outcomes.
Prospective comparative study of two electronic literature search strategies. The ‘generic’ search included general terms for health such as ‘adolescent health’, ‘health status’, ‘morbidity’, etc. The ‘specific’ search focused on terms for a range of specific illnesses, such as ‘headache’, ‘epilepsy’, ‘diabetes mellitus’, etc.
The authors searched Medline, Embase, the Cumulative Index to Nursing and Allied Health Literature, PsycINFO and the Education Resources Information Center for studies published in English between 1992 and April 2010.
Main outcome measures
Number and proportion of studies included in the systematic review that were identified from each search.
The two searches tended to identify different studies. Of 41 studies included in the final review, only three (7%) were identified by both search strategies, 21 (51%) were identified by the generic search only and 17 (41%) were identified by the specific search only. 5 of the 41 studies were also identified through manual searching methods. Studies identified by the two ELS differed in terms of reported health outcomes, while each ELS uniquely identified some of the review's higher quality studies.
Electronic literature searches (ELS) are a vital stage in conducting systematic reviews and therefore have an important role in attempts to inform and improve policy and practice with the best available evidence. While the use of both generic and specific health terms is conventional for many reviewers and information scientists, there are also reviews that rely solely on either generic or specific terms. Based on the findings, reliance on only the generic or specific approach could increase the risk of systematic reviews missing important evidence and, consequently, misinforming decision makers. However, future research should test the generalisability of these findings.
Providing evidence-based guidance to improve electronic literature searches (ELS): an often overlooked but vital stage in our efforts to inform policy and practice with the best available evidence.
During systematic review literature search we conducted two ELS and compared the results: one ELS included search terms for a range of specific health conditions, while the other included only generic terms for health and illness.
Future systematic reviews that involve multiple health outcomes should include both generic and specific health terms in their literature search.
Based on our findings, previous reviews that have only used one of these approaches may have failed to identify relevant evidence and this in turn could have affected the reviewers' conclusions.
Systematic reviews that miss important evidence risk causing harm by misinforming practitioners and other decision makers.
Strengths and limitations of this study
The relatively novel application of a prospective comparative study design to the issue of electronic literature searching is a key strength.
Although the searches identified over 10 000 initial records, they could have been made more sensitive through greater use of techniques such as truncation, synonyms and by searching additional databases.
The study is based on searches conducted for a specific review, so the generalisablity of our findings should be tested in the context of other reviews and different types of literature search, including more sensitive searches.