Step 2: Acquire (Search)
Once you have converted your clinical problem into an answerable question, you can start acquiring information to answer your question.
First you need to consider which types of resources best meet your needs. This will help you decide where you are going to search for information. Once you know what to search for and where to search, you can use your PICO elements to plan your search and locate high quality resources.
Levels of evidence
When searching for information, you need to select the highest level of evidence possible. However, some resources are considered to have a higher level of evidence than others.
The 6s Hierarchy of Evidence-Based Resources represents the different levels of evidence and how they build on each other. Levels of evidence are assigned to studies based on the methodological quality of their design, validity, and applicability to patient care. As you move up the pyramid, the quality of information increases but the amount of available information decreases.
The top 5 levels of the pyramid are considered secondary resources because they critically appraise and synthesise the best evidence from lower levels of the hierarchy to determine best practice approaches.
Select the plus symbols below to learn more about the levels of evidence.
The above figure (DiCenso, Bayley & Haynes 2009, p. 100) has been adapted with permission from British Medical Journal, 2022
It’s best to start your search for information in resources found at the top of the pyramid, where the research evidence has been pre-appraised by health care experts. However, because there is less information available, you will need to search broadly, using one keyword at a time and gradually adding more.
If you are unable to find relevant information, move down to the next highest level in the pyramid. As you work your way down the pyramid, more research will be available so you can be more specific with your search.
Study designs
Primary research studies are conducted using a variety of study designs, which are not considered to have the same level of evidence. Again, you should start searching for resources that have the highest evidence level, and work your way down if studies are unavailable. If you are unable to find resources from the top sections of the pyramid, you will need to search for research articles.
Different study designs are also best suited to support different types of clinical questions, and it's important to know which study designs you should be searching for.
Use the arrows to move through the slides below to learn more. Select the blue link button to view an example of each study design type.
Please expand the window for the best viewing experience.
The first slide in the deck above provides a breakdown of primary and secondary research output. More information about primary and secondary databases is available on the Systematic Review guide.
Watch the video below to learn more about clinical question types and the relevant study designs.
Duke University Medical Centre Library & Archives 2010, EBM and study design,
Running time: 12:18 minutes
In the video below, Dr. Saravana Kumar, Professor in Allied Health and Health Services Research, UniSA, explains the different question types, and the body of evidence required for each.
Test your knowledge
How to plan your search
A search strategy is the combination of keywords that you will type into the search box of your selected database. There are four key steps involved in creating a search strategy.
Select the headings below to learn more about each step.
It's okay to have more than one keyword or phrase for each PICO element.
You may not need to search for your outcome. It may be difficult to define in your search, so you may accidentally exclude useful papers, or you may introduce a publication selection bias by excluding papers where your proposed outcome did not result.
Think about including:
- synonyms
e.g. back pain + back ache - medical terminology and common words
e.g. back pain + lumbago - British and American spelling
e.g. aetiology + etiology - plurals
e.g. man + men - different word endings
e.g. treat + treats + treated + treatment - hyphenated and non-hyphenated words
e.g. low-back pain + low back pain - acronyms
e.g. low back pain + LBP
Tip #1: Use double quotes to search for phrases
e.g. "low back pain" finds these words in this exact order
Tip #2: Use an asterisk * to find different word endings
e.g. treat* finds treat, treats, treated, treatment
Tip #3: Use a question mark ? to find different spelling
e.g. m?n finds man and men
The How to save time searching databases information sheet has more information.
Combine similar keywords
For each key element, you need to link your list of keywords together using OR. This tells the database to search for resources that contain any of these words. The more words you add using OR, the more results you will get.
For example:
PICO element 1 OR alternative term OR alternative term
Combine different keywords
Each set of keywords then need to combined using AND. This tells the database to search for at least one word from each of your keyword sets.
For example:
PICO element 1 OR alternative term OR alternative term
AND
PICO element 2 OR alternative term OR alternative term
AND
PICO element 3 OR alternative term OR alternative term
Where to search
- The Cochrane Library The Cochrane Library is a collection of databases that contain different types of high-quality, independent evidence to inform healthcare decision-making.
- Library Collection Include the word 'textbook' in your search, and then apply the Books filter.
Search tip: find summaries by applying filters for guidelines, protocols, textbooks, or patient information.
**Note: The names of relevant filters may be different in different databases.
Search tip: find synopses of syntheses by applying filters for clinical answers.
**Note: The names of relevant filters may be different in different databases.
Search tip: find syntheses by applying filters for systematic reviews or meta-anlyses.
**Note: The names of relevant filters may be different in different databases.
- Health Collection (via Informit)Covers health-related material from and about Australia, New Zealand, the Pacific and South East Asia. Focuses on nursing and allied health, with key subjects including public health, patient care, aged care, Aboriginal Australians, child welfare and family violence.
- ScienceDirectFor peer reviewed articles on a large range of subjects including health
Search tip: find studies by applying filters for the relevant study design.
**Note: The names of relevant filters may be different in different databases.
- Library Collection Include the word 'textbook' in your search, and then apply the Books filter.
The table below shows which databases are relevant for each type of evidence. The colour coding relates to the levels of evidence pyramid.
How to search in databases
The Library Collection is a great place to search for summary level resources including textbooks, handbooks, and introductory texts. These should be the first resources you look for.
Search tip: Remember to use broad keywords and apply the Books filter.
Medline is a great place to search for syntheses (systematic reviews and meta-analyses), synopses of studies, and primary studies.
Search tip: Filter your results by relevant study design (based on the question type) once you have searched.
Emcare is a great place to search for syntheses (systematic reviews and meta-analyses), synopses of studies, and primary studies.
Search tip: Filter your results by relevant study design (based on the question type) once you have searched.
The Cochrane Library is a great place to search for summaries (guidelines and protocols), synopses of syntheses (clinical answers), and syntheses (systematic reviews and meta-analyses).
Search tip: Use the filters to refine your search to different publication types.
Scopus is a great place to search for primary studies.
Search tip: find studies by applying filters for the relevant study design.
Google Scholar is a great place to search for syntheses (systematic reviews and meta-analyses) and primary studies.
Google is good for finding summaries (guidelines, protocols and patient information) from authoritative organisations.
