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Acquiring Evidence

Search Filters

Search filters are standardized strategies that help identify higher quality literature within many of the medical databases. They are very useful for narrowing a search to high quality study designs but can also be used for other topics or age groups.

To incorporate a search filter into a search strategy, use AND to combine the final set of subject search with the final set of the filter.

Comprehensive Lists of Search Filters

Randomized Controlled Trial Filters

Medline (OVID Version) 

  • Based on Glanville JM, Lefebvre C, Miles JNV, Camosso-Stefinovic J. How to identify randomized controlled trials in MEDLINE: ten years on. J Med Libr Assoc 2006 Apr;94(2):130–6.
  • Available in Expert Searches under "PHS 692 MEDLINE Cochrane RCT Filter"
1. randomized controlled
2. clinical
3. randomi?ed.ti,ab.
4. placebo.ti,ab.
5. dt.fs.
6. randomly.ti,ab.
7. trial.ti,ab.
8. groups.ti,ab.
9. or/1-8
10. animals/
11. humans/
12. 10 not (10 and 11)
13. 9 not 12


PubMED ♦

  • Based on Glanville JM, Lefebvre C, Miles JNV, Camosso-Stefinovic J. How to identify randomized controlled trials in MEDLINE: ten years on. J Med Libr Assoc 2006 Apr;94(2):130–6.

("Clinical Trial"[Publication Type] OR groups[Title/Abstract] OR placebo*[Title/Abstract] OR trial*[Title/Abstract] OR random*[Title/Abstract] OR "drug therapy"[Subheading]) NOT ((animals[MeSH Terms]) NOT ((animals[MeSH Terms]) AND (humans[MeSH Terms])))



  • Available in Expert Searches under "PHS 692 Embase RCT Filter"
1. exp clinical trial/
2. randomi?ed.ti,ab.
3. placebo.ti,ab.
4. dt.fs.
5. randomly.ti,ab.
6. trial.ti,ab.
7. groups.ti,ab.
8. or/1-7
9. animal/
10. human/
11. 9 not (9 and 10)
12. 8 not 11


CINAHL (EBSCO Version) ♦

  • Derived from The Editorial Team. Specialized Register, CINAHL In Cochrane Stroke GroupAbout The Cochrane Collaboration (Cochrane Review Groups (CRGs)) 2013, Issue 10. Art. No.: STROKE.

( (MH "Random Assignment") or (MH "Random Sample+") or (MH "Crossover Design") or (MH "Clinical Trials+") or (MH "Comparative Studies") or (MH "Control (Research)+") or (MH "Control Group") or (MH "Factorial Design") or (MH "Quasi-Experimental Studies+") or (MH "Placebos") or (MH "Meta Analysis") or (MH "Sample Size") or (MH "Research, Nursing") or (MH "Research Question") or (MH "Research Methodology+") or (MH "Evaluation Research+") or (MH "Concurrent Prospective Studies") or (MH "Prospective Studies") or (MH "Nursing Practice, Research-Based") or (MH "Solomon Four-Group Design") or (MH "One-Shot Case Study") or (MH "Pretest-Posttest Design+") or (MH "Static Group Comparison") or (MH "Study Design") or (MH "Clinical Research+") ) or ( clinical nursing research or random* or cross?over or placebo* or control* or factorial or sham* or meta?analy* or systematic review* or blind* or mask* or trial* ) 


Web of Science ♦ - 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*)


♦ Search filter can be cut and paste directly into the Advanced Search box of the database