Manual search approaches used by systematic reviewers in dermatology.
OBJECTIVE
Manual searches are supplemental approaches to database searches to identify additional primary studies for systematic reviews. The authors argue that these manual approaches, in particular hand-searching and perusing reference lists, are often considered the same yet lead to different outcomes.


METHODS
We conducted a PubMed search for systematic reviews in the top 10 dermatology journals (January 2006-January 2016). After screening, the final sample comprised 292 reviews. Statements related to manual searches were extracted from each review and categorized by the primary and secondary authors. Each statement was categorized as either "Search of Reference List," "Hand Search," "Both," or "Unclear."


RESULTS
Of the 292 systematic reviews included in our sample, 143 reviews (48.97%) did not report a hand-search or scan of reference lists. One-hundred thirty-six reviews (46.58%) reported searches of reference lists, while 4 reviews (1.37%) reported systematic hand-searches. Three reviews (1.03%) reported use of both hand-searches and scanning reference lists. Six reviews (2.05%) were classified as unclear due to vague wording.


CONCLUSIONS
Authors of systematic reviews published in dermatology journals in our study sample scanned reference lists more frequently than they conducted hand-searches, possibly contributing to biased search outcomes. We encourage systematic reviewers to routinely practice hand-searching in order to minimize bias.
Matt
M
Vassar
Paul
P
Atakpo
Melissa J
MJ
Kash
D016206:Databases, Bibliographic; D003880:Dermatology / Q000379:methods / Q000592:standards; D019317:Evidence-Based Medicine / Q000379:methods / Q000592:standards; D006801:Humans; D016247:Information Storage and Retrieval / Q000379:methods* / Q000706:statistics & numerical data; D010506:Periodicals as Topic; D012196:Review Literature as Topic
Bias (Epidemiology); Bibliographic; Bibliometrics; Clinical Studies as Topic; Data Collection; Databases; Information Storage and Retrieval; Periodicals as Topic; Publishing; Review Literature as Topic