Search Filters and Blocks

What is a search filter?

Search filters, search blocks or hedges are 'ready-made' combinations of terms in free-text or subject headings that are regularly used in expert searching. They are generally validated lists of terms which have been tested to check that they retrieve the expected research on that topic.

The ones listed below have been tested and information is provided the databases the filter work in (and perhaps what amendments are needed to make them work in other databases).

Where to find search filters

General Collections

EAHIL Search Blocks collection – An aggregated list of sites containing search blocks or filters (collected as a result of EAHIL workshops.)

BMI Online - Searchable collection which includes diseases and treatment, geographic locations, guidelines, professional and population groups, methodologies and study types.

CADTH Search Filters Database – Collection of filters developed and maintained by CADTH’s Research Information Services Filters Working Group

PubMed general search filters – Provides filters on topics including Covid-19,

PubMed Subject Filters – Provides information on topic specific filters available through PubMed, eg cancer, health literacy

PubMed Search Strategies - A blog recording search filters on a huge variety of topics.

Ovid Expert Searches is a collection of expert searches on a variety of health topics, diseases and treatment, and search filters.

Adverse events – see Golder, S. and Loke, Y. Search strategies to identify information on adverse effects: a systematic review. Journal of the Medical Library Association : JMLA, Vol. 97, No. 2. (April 2009), pp. 84-92, doi: 10.3163/1536-5050.97.2.004 

searchRxiv - A database of search strategies.

Methodological Search Filters

The filters available through these resources focus on a particular type of clinical question,

InterTASC Search Filter Resource - Collection of filters to retrieve research by study design or focus.

PubMed Clinical Queries Filters

McMasters University HIRU Hedges project - These search filters were developed and validated by researchers in HiRU are available for use on PubMed’s Clinical Queries page (see previous).