The focus of the Hedges Project is to investigate ways to develop and harness (“hedges”) to improve retrieval of scientifically sound and clinically relevant study reports from large, general purpose, biomedical research bibliographic databases including MEDLINE, EMBASE, and PsycINFO. The purposes of the search filters are:
- To enable health care providers to do their own clinical searches effectively and efficiently
- To help reviewers of published evidence on health care problems retrieve all relevant citations
- To provide resources for librarians to help clinicians to construct their own searches
- To provide input to database producers about their indexing processes and organization of their databases
Improved search filters are important given problems with the timeliness of indexing and the widespread direct use of these databases by clinicians, researchers, and other users, whose interests are primarily directed towards a very small subset of the literature. Our objective is to harness the highest quality, clinically relevant contents of these electronic databases so that their effects on health care and policy can be enhanced. The Hedges Project was funded by the US National Library of Medicine and Canadian Institutes of Health Research.
Click on the following links to view the search filters for MEDLINE, EMBASE, and PsycINFO.
Our Clinical Hedges database contains data for the year 2000 for each article in each of the issues of 170 clinical journals. 161 of these journals were indexed in MEDLINE and 135 were indexed in EMBASE. Expert and highly calibrated research staff identified and tagged the records for articles that reported original and review studies (definitions shown in Table 1) about the cause (causation [etiology]), course (prognosis), diagnosis, prevention or therapy or rehabilitation, clinical prediction, or economics of human health disorders, as well as studies of quality improvement of health services, the continuing education of health professionals, and studies of a qualitative nature (definitions shown in Table 2). Studies in these “purpose categories”, except for qualitative and cost studies, were further tagged for whether they “pass” or “fail” pre-specified methodologic criteria for applied clinical research (criteria shown in Table 3).
MEDLINE
To develop search filters in MEDLINE we assembled a list of search terms and phrases in a subset of MEDLINE records matched with a hand search of the contents of 161 journal titles for the year 2000. The search filters were treated as “diagnostic tests” for sound studies and the manual review of the literature was treated as the “gold standard”. The sensitivity for a given filter is defined as the proportion of high-quality articles that are retrieved; specificity is the proportion of low quality or off topic articles not retrieved; precision is the proportion of retrieved articles that are of high quality; and accuracy is the proportion of all articles that are correctly categorized by the search filter. 49,028 articles were included in the analysis and 4,862 unique single-terms were tested.
EMBASE
To develop search filters in EMBASE, we assembled a list of search terms and phrases in a subset of EMBASE records matched with a hand search of the contents of 55 of the 135 journals titles indexed in the year 2000. Search strategies were developed using a 55-journal subset chosen based on those journals that had the highest number of methodologically sound studies, that is, studies that clinicians should be using when making patient care decisions. This selection enriches the sample of target articles, improving the precision of estimates of search term performance and simplifying data processing, but is unlikely to bias the estimates of the sensitivity and specificity of search terms. As with MEDLINE, search strategies were treated as “diagnostic tests” for sound studies and the manual review of the literature was treated as the “gold standard”. 27,769 articles were included in the analysis and 4,843 unique single-terms were tested.
Click the following links to view Search Strategies for CINAHL, KT CINAHL Filter Tables and Nephrology Filter Tables
If you have any questions regarding clinical queries, contact Tamara Navarro. For any questions regarding HKR, contact Dr. Lori Linkins.