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- 20 April 2016
See also Evidence-based health care | Grey literature | Scoping reviews | Search filters & hedges | Snowballing | Systematic review searching
"...Handsearching refers to the planned searching of a journal page by page (i.e. by hand), including editorials, letters, etc., to identify all reports of randomised controlled trials and controlled clinical trials. All identified trials, regardless of topic, are sent to the United States Cochrane Center, for inclusion in CENTRAL, and forwarding to the US National Library of Medicine (NLM) for re-tagging in MEDLINE. Trials that are within the scope of a Collaborative Review Group or Field go into their specialised register of trials. A handsearching manual is available through the US Cochrane Center. A journal handsearch registration form must be completed for each journal title and sent to the US Cochrane Center to avoid duplication of effort..."
Hand-searching (aka., handsearching, hand searching) is a manual method of searching through select journals from cover to cover, page-for-page, for articles and citations relevant to the systematic review. Hand-searching is an extended search technique (beyond Medline) used to find studies that may have been missed during searching or indexing. According to the Cochrane Handbook, "...handsearching involves a manual page-by-page examination of the entire contents of a journal issue or conference proceedings to identify all eligible reports of trials." Handsearching may include checking the reference lists of journal articles, a technique called snowballing. In 2013, Craane et al found that "...hand search[ing] plays a valuable role in identifying randomised controlled trials" beyond Medline and Embase (and sometimes within those databases if missed by the search).
Hand-searching may be thought of as some (or most) of the following:
- A widely-used expert search method (or extended search technique) first introduced in the 1990s by the Cochrane Collaboration.
- A type of extended search technique (along with key informant interviews) and discussed in detail by the Cochrane Handbook.
- A form of manual searching; hand-searching can be thought of as a kind of digital browsing in online contexts.
- Authors are not routinely expected to undertake handsearching but may be required to do so by the information retrievalist on a research team.
- While databases aim to index all articles within a journal, it may be important to scan for items that have been missed somehow in the abstracting and indexing process via a thorough review of each journal issue.
- This can be done online or from the print journal when available. With the availability of so many online alternatives to hand-searching, combined hand- and electronic-search strategies may be necessary to adequately locate all relevant research for narrative and scoping reviews. (See Davis 2003).
- Hand-searching is typically carried out by hand-searchers (often health librarians) and must be documented along other search strategies.
- Recent research by health librarians suggests that hand-searching is still a requirement for the systematic review.
- Although keyword searching and reference harvesting reduce the need to do hand-searches, it is thought that hand-searching (due to non-existent, incomplete and / or inaccurate indexing) supplements searches that are well-structured and documented in the biomedical databases.
- The law of diminishing returns in searching may mean that hand-searching will be more effective than more searching online.
Use of hand-searching for systematic reviews
"Handsearching" requires a trained person to check a journal from cover to cover, reading each article until they are satisfied whether or not it is definitely or possibly a report of a randomized controlled trial or a quasi-randomized controlled trial." ~ Egger, 2001
As outlined, hand-searching is a manual process of screening pre-defined and pre-selected peer-reviewed biomedical journals, conference proceedings and other publications for relevant materials that have been missed during the indexing process. Hand-searching is widely considered necessary in the systematic review because it:
- locates relevant articles poorly or inaccurately indexed or unindexed;
- allows researchers to scan content quickly for relevant studies from the high-impact journals, and
- ensures that relevant studies are not overlooked
The digital equivalent to hand-searching might best be described as digital-browsing or power-browsing.
Why search by hand?
...hand searching journals has been identified as vitally important to conducting a high quality systematic review
as not all journals are indexed in electronic databases or may be missed by the search strategy used..." ~ Armstrong et al, 2005
Hand-searching increases the likelihood that no major relevant studies will be missed. Due to selective indexing in some databases and search tools and a tendency not to index supplements or special issues such as conference abstracts, handsearching is important for many if not most major research projects where comprehensive retrieval is required. If major journals in a specific field are not obvious to those handsearching, Journal Citation Reports is used to provide a list of the most influential journals with the highest impact factors.
Documentation of handsearching & powerbrowsing
Specific titles and date ranges searched for a systematic review should be included in the search strategies section. It should include journal titles, listed in alphabetical order, and the months and years that have been searched. In addition, any websites that have been consulted, whether it be for the purposes of browsing for information, searching for grey literature or locating experts in the field, should also be documented.
- synonyms for hand-searching & powerbrowsing: backward chaining, footnote chasing, pearl growing, reference harvesting, reference searching, and so on.
Note: One of the legitimate questions for health librarians in an era where many biomedical journals are born-digital is how hand-searching has changed without the physical objects to hold in hand. Browsing a print journal physically is a tactile experience and differs from browsing the same journal online. Systematic review searchers will need to be cognizant of the differences in handsearching in the digital era and take steps not to miss important studies.
Websites & courses
- Aoki NJ, Enticott JC, Phillips LE. Searching the literature: four simple steps. Transfusion. 2013 Jan;53(1):14-7.
- Armstrong R, Jackson N, Doyle J. It's in your hands: the value of handsearching in conducting systematic reviews of public health interventions. J Public Health. 2005;27(4):388-91.
- Booth A. Unpacking your literature search toolbox: on search styles and tactics. Health Info Libr J. 2008;25:313-317.
- Blümle A, Antes G, Diener MK. Hand searching for controlled clinical trials in German surgical journals: a contribution to evidence-based surgery. Chirurg. 2007;78(11):1052-7.
- Centre for Reviews and Dissemination. Systematic Reviews: CRD’s guidance for undertaking reviews in health care. UK Centre for Reviews and Dissemination
- Chapman AL, Morgan LC, Gartlehner G. Semi‐automating the manual literature search for systematic reviews increases efficiency. Health Info Libr J. 2010;27(1):22-27.
- Damarell RA, Tieman J, Sladek RM, Davidson PM. Development of a heart failure filter for Medline: an objective approach using evidence-based clinical practice guidelines as an alternative to hand searching. BMC Med Res Methodol. 2011;28;11:12.
- Delamere FM, Williams HC. How can hand searching the dermatological literature benefit people with skin problems? Arch Dermatol. 2001;137(3):332-5.
- Gasparyan AY, Ayvazyan L, Kitas GD. Multidisciplinary bibliographic databases. J Korean Med Sci. 2013 Sep;28(9):1270-1275.
- Giustini D, Boulos MNK. Google scholar is not enough to be used alone for systematic reviews. OJPHI. 2013 July;5(2).
- Glanville J, Cikalo M, Crawford F, Dozier M, McIntosh H. Handsearching did not yield additional unique FDG-PET diagnostic test accuracy studies compared with electronic searches: a preliminary investigation. Res Synth Methods. 2012Sep;3(3):202-13.
- Higgins JPT, Green S. Cochrane handbook for systematic reviews of interventions. Cochrane Library. Chichester, UK: John Wiley; 2006.
- Hopewell S, Clarke M, Lefebvre C, Scherer R. Handsearching versus electronic searching to identify reports of randomized trials. Cochrane Database Syst Rev. 2007;(2).
- Holst R, Funk CJ. State of the art of expert searching: results of a Medical Library Association survey. J Med Libr Assoc. 2005 Jan;93(1):45-52.
- Hunt DL, McKibbon KA. Locating and appraising systematic reviews. Ann Int Med. 1997;126:532-8.
- Langham J, Thompson E, Rowan K. Identification of randomized controlled trials from the emergency medicine literature: comparison of hand searching versus MEDLINE searching. Ann Emerg Med. 1999;34(1):25–34.
- Librarians Named in New IOM Standards for Systematic Reviews. Finding What Works in Health Care: Standards for Systematic Reviews, one of two new reports just issued by the Institute of Medicine (IOM), recommends twenty-one standards for performing high-quality reviews. Librarians and other information specialists are mentioned under the “Standards for Finding and Assessing Individual Studies” in how to conduct comprehensive systematic searches for evidence.
- Mattioli S, Farioli A, Cooke RM. Hidden effectiveness? Results of hand-searching Italian language journals for occupational health interventions. Occup Environ Med. 2012 Mar 23.
- Ramer SL. Site-ation pearl growing: methods and librarianship history and theory. J Med Libr Assoc. 2005;93(3):397-400.
- Richards D. Handsearching still a valuable element of the systematic review. Evid Based Dent. 2008;9(3):85.
- Search Strategies to Identify Reviews and Meta-analyses in MEDLINE and CINAHL
- Sampson M, Zhang L, Morrison A, Barrowman NJ, Clifford TJ. An alternative to the hand searching gold standard: validating methodological search filters using relative recall. BMC Med Res Methodol. 2006;6:33.
- Shojania KG, Sampson M, Ansari MT, Ji J, Doucette S, Moher D. How quickly do systematic reviews go out of date? A survival analysis. Ann Intern Med. 2007;147(4):224–33.
- Shaw B, Worthington H. Hand-searching for systematic reviews. Br Dent J. 2001;190(12):632.