Table 2Recommended sources of grey literature for conventional drugs and devices

Type of InformationRecommended Sources or StrategiesWhen To SearchReporting Bias TypeProvisosRecommendation(s) Empiric Evidence (E) or Consensus (C)
Study protocol elements (Methods), outcomes data (Results), or completely missing studiesClinicalTrials.gov
ICTRP
RoutinelySOR/SAR/Publication biasStudies conducted in 2005 and onwardsE
Study protocol elements (Methods), outcomes data (Results), or completely missing studiesFDA
EMA
RoutinelySOR/SAR/Publication biasIndication approved drugs, and class III devicesE
Missing studiesConference abstracts and proceedingsRoutinely, on advice of KI or TEPPublication biasE
Missing studiesGrant databases (e.g. Research Portfolio Online Reporting Tools)On KI or TEP recommendationPublication biasC
Study protocol elements (Methods) or outcomes data (Results)Study AuthorsFor data clarifications (regarding study eligibility, study design, or other aspects of study conducts)SOR/SARNo more than three attemptsC
Study protocol elements (Methods), outcomes data (Results), or completely missing studiesIndustry SIPs, Industry maintained trial registries, and DIDARoutinely for SIPs and DIDA
At reviewers discretion for Industry maintained trial registries
SOR/SAR/publication biasEPCs should not contact the Industry directly, SIPs through SRCC
Study protocols, companion papers, or completely missing studiesHand searchingRoutinely search the Cochrane Central Register of Controlled Trials
Hand searching of selected journals at reviewers discretion
SOR/SAR/Location biasC
Study protocols, companion papers, or completely missing studiesNon-English language literatureSearch routinelyaLanguage biasC
Study protocols, companion papers, or completely missing studiesCitation searching using the World Wide WebNot recommendedSOR/SAR/Publication biasC

Note: DIDA = Drug Industry Document Archive, EMA = European Medical Agency, EPC = Evidence-based Practice Center, FDA = U.S. Food and Drug Administration, ICTRP = International Clinical Trials Registry Platform, KI = Key Informant, SAR = selective analysis reporting, SIP = scientific information packet, SOR = selective outcome reporting, SRC=Scientific Resource Center, TEP = Technical Expert Panel.

a

Search criteria only, not eligibility criteria. If non-English language literature is excluded, a list of potentially relevant but excluded literate can help inform the potential risk of language bias.

From: Finding Grey Literature Evidence and Assessing for Outcome and Analysis Reporting Biases When Comparing Medical Interventions: AHRQ and the Effective Health Care Program

Cover of Methods Guide for Effectiveness and Comparative Effectiveness Reviews
Methods Guide for Effectiveness and Comparative Effectiveness Reviews [Internet].

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