Step 2: Gather Evidence

Now that you’ve formulated your PICO question, the next step is to gather evidence that addresses your question. There are two types of evidence to consider: internal evidence and external evidence.

Internal evidence refers to the data that you systematically collect directly from your clients to ensure that they’re making progress. This data may include subjective observations of your client as well as objective performance data compiled across time. Use your clinical expertise to determine what information is most important to track for your client’s specific situation and needs. Armed with internal evidence unique to your client, you are better prepared to find targeted external evidence that will help you make a clinical decision.

External evidence refers to evidence from scientific literature—particularly the results, data, statistical analysis, and conclusions of a study. This evidence helps you determine whether an approach or a service delivery model might be effective at implementing change in individuals like your client.

Below are some things to consider when organizing and completing your search for external evidence:

• How should you plan your search for external evidence?
• What type of external evidence is needed to answer your question?
• Where should you search for external evidence?
• What should you do if you are unable to find external evidence?

How should you plan your search for external evidence?

A well-planned search increases the likelihood that you will find relevant external evidence that answers your PICO question. Below are some tips to help you get started with your search:

Develop a list of search terms.

Create a list of search terms using elements from your PICO question. It may not be necessary to include all PICO elements in your search, but these key concepts are a good place to start.          
Example: What is the population, patient, or problem of interest? What is the main intervention or issue being considered? What outcome do you want to accomplish?

Consider synonyms, related terms, and acronyms for each key term. Using synonyms or related words can help you expand your search.
Example: If searching for traumatic brain injury, include "traumatic brain injury", "TBI", and "acquired brain injury".

Set parameters for your search.

Combine keywords and phrases using terms such as "OR" and "AND" (known as Boolean operators) to broaden or narrow your search results.

• Use "OR" to increase your search results and find evidence that contains either term (e.g., "dysphagia OR swallowing"; "teenagers OR adolescents").
• Use "AND" to limit your search and find evidence that must contain both words (e.g., "stroke AND aphasia"; "children AND hearing loss").

Apply limits and filters to narrow your search (e.g., date range, language). A date limit may be helpful, particularly when a search retrieves too many results. Date limits may also be helpful if your question involves more recent technology or practice (e.g., ""digital hearing aids", "telepractice"). 

Stay organized.

Write down the key terms searched, the databases used, and the search parameters applied.

Keep track of your search results. This will help you identify the most effective search terms, eliminate duplicate citations, and ultimately save you time.  

Translating a PICO Question Into Search Terms

Example Clinical Question—Does cognitive rehabilitation improve cognitive skills in adults with traumatic brain injury?

Learn how to turn these keywords into a search strategy for your PICO question.

What type of external evidence is needed to answer your question?

Different questions (e.g., therapy/treatment, diagnostic, prevention) may be better addressed by different study designs. For example, determining the effect of a treatment on a specific patient population compared with an alternative or no treatment may be best addressed by a randomized controlled trial. Knowing the type of clinical question that you are asking can help you limit your search and narrow your results to the most applicable research design for your question. 

Synthesized evidence can save time.

In addition to searching for individual study designs, clinicians can save time by looking for synthesized evidence. With synthesized evidence, researchers take a clinical question, gather available evidence, and make conclusions or recommendations about the body of research.

There are various types of synthesized evidence.

A systematic review is a formal assessment of the body of scientific evidence related to a clinical question and describes the extent to which various diagnostic or treatment approaches are supported by the evidence. Systematic reviews that use statistical techniques to pool data and draw conclusions across studies are known as meta-analyses. These documents provide comprehensive summaries of the evidence but stop short of recommending clinical practices.

Alternatively, clinical practice guidelines, developed by a group of topic experts, provide recommendations for managing a specific condition or population to optimize care. Guidelines may also discuss possible benefits and harms of a clinical action and recommend alternative approaches. Guidelines can be evidence based or consensus based.

• Evidence-based guidelines provide recommendations based on an evidence-based systematic review. These recommendations are often rated according to the quality and strength of the evidence.
• Consensus-based guidelines provide recommendations formed by consensus or agreement among topic experts without an evidence-based systematic review.

Where should you search for external evidence?

Searching for evidence can be a daunting task. Knowing where to search can save you valuable time in the EBP process.

Begin where you are most likely to find evidence related to your clinical question, such as databases specific to CSD research or related disciplines (e.g., education, rehabilitation). 

• ASHAWire
• speechBITE™
• ERIC (Education Resources Information Center)

Look for evidence that has already been appraised or synthesized. Guidelines, systematic reviews, and meta-analyses, if done well, can be a trustworthy sources of information. Some databases and resources focus on synthesized and appraised research that covers a variety of clinical topics.

• ASHA's Evidence Maps
• The Cochrane Library
• Campbell Collaboration 
• What Works Clearinghouse (U.S. Department of Education)

Look for individual studies when evidence from guidelines, systematic reviews, or meta-analyses is unavailable, out of date, unreliable, or irrelevant. Many databases (such as those listed below) allow you to search for individual studies and to limit your search by research design. 

• PubMed (MEDLINE)
• PsycNet
• JSTOR

Although these databases are free to search, some may not provide the full text of all articles. A number of resources are available to access full-text articles—these resources include academic networking sites, a university or local library system, or the publisher.

What should you do if you are unable to find external evidence?

Sometimes, despite your best efforts, you find few or no articles related to your clinical question. If this happens, here are some strategies:

• Reconsider your PICO question and/or search terms. Try broadening your search. Add more synonyms or common acronyms to your search terms.
• Consider research from similar or related populations, interventions, or outcomes. Use your clinical judgment to decide whether such information could be helpful for your client.
• Find an alternative assessment, treatment, or service delivery option that is evidence-based.
• Review and analyze your internal evidence, or client data, to find any changes or patterns that may guide your clinical decision.