Inclusion | Exclusion | |
---|---|---|
KQ 1: Methods to recover falsely excluded studies | • Reference list checking of included studies • Similarity searches (i.e., related articles) • Forward citation tracking of included studies using citation indexes • Google Scholar search • Contacting experts/researchers/companies/other stakeholders | Other methods |
KQ 2: Potential predictors of false exclusion | • Study design • Main objective • Sample size • Country of conduct • Year of publication • Structure and content of abstract (e.g., only title available, no abstract, uninformative abstract) • Language of publication • Risk of bias • Database indexing of studies (e.g., PubMed listing) • Publication type • Journal in which the study is published • Impact factor of journal in which the study is published • Others | |
Outcomes | • Proportion of falsely excluded studies that could be recovered (KQ 1) • Recall, precision, numbers needed to read (NNR) of supplementary searches (KQ 1) • Impact of recovered studies on meta-analysis results and conclusions (KQ 1) • Falsely excluded studies by characteristics (KQ 2) • Falsely excluded studies by predictors (KQ 2) | Other outcomes |
Study design | • Systematic reviews (KQ 1, 2) • Randomized/nonrandomized trials (KQ 1, 2) • Prospective and retrospective, controlled and uncontrolled observational studies (KQ 1, 2) | Nonempirical publications (e.g., editorials, letters) |
Date of search | Published 1999 or later | 1998 and earlier |
Publication language | No restrictions | No restrictions |