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Systematic Reviews: Search Filters / Hedges

A guide for those who want to do a Systematic Review search strategy mainly in the health sciences field

Hedges or Filters by Study Design

After running a search strategy on resources such as Medline/Pubmed, use any of below validated filters/hedges (developed to balance precision and recall) to limit search to RCT, Systematic Reviews, etc...

Advice: Don't limit by study methodology unless you have to!

This is because in most cases, such limits result in missing relevant studies due to 1) large variety of terms used to describe study types 2) many authors never mention methodologies in title/abstract 3) inconsistent indexing in particularly for non-randomized designs.

But if You Have to Limit ...

If retrieved results are unmanageable and you need a methodology filter, use validated filters that have been tested against gold-standard sets.

 

Additional Libguides about search hedges:

Harvard search filters for systematic reviews

RCT Filters

Medline OVID filter from Cochrane - Max Sensitivity:
((randomized controlled trial.pt. or controlled clinical trial.pt. or randomized.ab. or placebo.ab. or drug therapy.fs. or randomly.ab. or trial.ab. or groups.ab.) not (exp animals/ not humans.sh.))

Medline OVID filter from Cochrane - Max specificity:
((randomized controlled trial.pt. or controlled clinical trial.pt. or randomized.ab. or placebo.ab. or clinical trials as topic.sh. or randomly.ab. or trial.ti.) not (exp animals/ not humans.sh.))

 

PubMed filter from Cochrane- Max Sensitivity:
(randomized controlled trial [pt] OR controlled clinical trial [pt] OR randomized [tiab] OR  placebo [tiab] OR drug therapy [sh] OR randomly [tiab] OR trial [tiab] OR groups [tiab]) NOT (animals [mh] NOT humans [mh])

PubMed filter from Cochrane - Max Specificity:
(randomized controlled trial[pt] OR controlled clinical trial[pt] OR randomized[tiab] OR placebo[tiab] OR clinical trials as topic[mesh:noexp] OR randomly[tiab] OR trial[ti]) NOT (animals [mh] NOT (humans [mh] AND animals[mh]))

 

EMBASE.com filter from Cochrane:
'crossover procedure':de OR 'double-blind procedure':de OR 'randomized controlled trial':de OR  'single-blind procedure':de OR (random* OR  factorial* OR crossover* OR cross NEXT/1 over* OR placebo* OR doubl* NEAR/1 blind* OR singl* NEAR/1 blind* OR assign* OR allocat* OR volunteer*):de,ab,ti

EMBASE.com filter from SIGN:
'clinical trial'/de OR 'randomized controlled trial'/de OR 'randomization'/de OR 'single blind procedure'/de OR 'double blind procedure'/de OR 'crossover procedure'/de OR 'placebo'/de OR 'prospective study'/de OR 'randomi?ed controlled' NEXT/1 trial* OR rct OR 'randomly allocated' OR 'allocated randomly' OR 'random allocation' OR allocated NEAR/2 random OR single NEXT/1 blind* OR double NEXT/1 blind* OR (treble OR triple) NEAR/1 blind* OR placebo*

 

CINAHL filter from SIGN:
TX allocat* random* OR (MH "Quantitative Studies") OR (MH "Placebos") OR TX placebo* OR TX random* allocat* OR (MH "Random Assignment") OR TX randomi* control* trial* OR TX ( (singl* n1 blind*) OR (singl* n1 mask*) ) OR TX ( (doubl* n1 blind*) OR (doubl* n1 mask*) ) OR TX ( (tripl* n1 blind*) OR (tripl* n1 mask*) ) OR TX ( (trebl* n1 blind*) OR (trebl* n1 mask*) ) OR TX clinic* n1 trial* OR PT Clinical trial OR (MH "Clinical Trials+")

 

PsycINFO filter from ProQuest:
SU.EXACT("Treatment Effectiveness Evaluation") OR SU.EXACT.EXPLODE("Treatment Outcomes") OR SU.EXACT("Placebo") OR SU.EXACT("Followup Studies") OR placebo* OR random* OR "comparative stud*" OR  clinical NEAR/3 trial* OR research NEAR/3 design OR evaluat* NEAR/3 stud* OR prospectiv* NEAR/3 stud* OR (singl* OR doubl* OR trebl* OR tripl*) NEAR/3 (blind* OR mask*)

 

Web Of Science (WoS) filter from University of Alberta - Not Validated

TS= clinical trial* OR TS=research design OR TS=comparative stud* OR TS=evaluation stud* OR TS=controlled trial* OR TS=follow-up stud* OR TS=prospective stud* OR TS=random* OR TS=placebo* OR TS=(single blind*) OR TS=(double blind*)

Miscellaneous Other Filters

University of Alberta has created a number of subject filters such as pediatrics, geriatrics, cancer, religion, end-of-life, social media, telehealth etc... all are available from the below link:

                          University of Alberta Subject Filters

Low and Middle Income Countries (LMIC) filter from Cochrane

Limit to Humans

To exclude animal studies while doing a systematic review, different databases require different search strategies. The below show these strategies according to the database used:

Medline - OVID: the below two lines work well to exclude animal studies in Medline, use either one:

FinalResult NOT (Animals/ NOT (Animals/ AND Humans/))

FinalResult NOT (exp animals/ not humans.sh.)

PubMed: below search strategy in PubMed will exclude animal studies from the final result:

FinalResult NOT ("Animals"[Mesh] NOT ("Animals"[Mesh] AND "Humans"[Mesh]))

OVID Embase:   

FinalResult NOT ((exp animal/ or nonhuman/) NOT exp human/)

Embase.com:     

FinalResult NOT ([animals]/lim NOT [humans]/lim)

Systematic Review Filter

Medline OVID filter from SIGN:
((Meta-Analysis as Topic/ or meta analy$.tw. or metaanaly$.tw. or Meta-Analysis/ or (systematic adj (review$1 or overview$1)).tw. or exp Review Literature as Topic/ or cochrane.ab. or embase.ab. or (psychlit or psyclit).ab. or (psychinfo or psycinfo).ab. or (cinahl or cinhal).ab. or science citation index.ab. or bids.ab. or cancerlit.ab. or reference list$.ab. or bibliograph$.ab. or hand-search$.ab. or relevant journals.ab. or manual search$.ab.) or ((selection criteria.ab. or data extraction.ab.) and review/)) not (comment/ or letter/ or editorial/)

 

CINAHL filter from SIGN:

(MH "Meta Analysis") OR TI meta analys* OR AB meta analys* OR TI Metaanaly* OR AB metaanalys* OR (MH "Literature Review+") OR TI systematic review* OR AB systematic review* OR TI systematic overview* OR AB systematic overview* NOT (PT commentary OR PT letter OR PT editorial OR MH animals+) 

 

ProQuest PsycINFO filter from Leicester University Hospitals

TI,AB,IF((comprehensive* OR integrative OR systematic*) NEAR/3 (bibliographic* OR review* OR literature)) OR TI,AB,IF((meta-analy* or metaanaly* or "research synthesis" or ((information or data) NEAR/3 synthesis) or (data NEAR/2 extract*))) OR TI,AB,IF(review NEAR/5 (rationale or evidence)) and ME("Literature Review") OR AB(cinahl or cinhal or (cochrane NEAR/3 trial*) or embase or medline or psyclit or psychlit or pubmed or scopus or "sociological abstracts" or "web of science") OR ME("systematic review" or "meta analysis")

 

Exclude Medline Results from PubMed

To get PubMed records not in Medline:
                  FinalResult NOT medline [sb]


Note: since there can be a slight time lag in getting from PubMed to Medline, it may also be worth searching PubMed for anything added in the past two or three days.

 

Qualitative Filters

CINAHL filter from University of Alberta

TS= clinical trial* OR TS=research design OR TS=comparative stud* OR TS=evaluation stud* OR TS=controlled trial* OR TS=follow-up stud* OR TS=prospective stud* OR TS=random* OR TS=placebo* OR TS=(single blind*) OR TS=(double blind*)

 

Scopus filter from University of Alberta

TS= clinical trial* OR TS=research design OR TS=comparative stud* OR TS=evaluation stud* OR TS=controlled trial* OR TS=follow-up stud* OR TS=prospective stud* OR TS=random* OR TS=placebo* OR TS=(single blind*) OR TS=(double blind*)