Finding the evidence - Using PICO searching to support evidence-based nursing practice

12 January 2018

Searching for high quality clinical research evidence can be a daunting task to many in the healthcare arena, yet it is an integral part of the evidence-based practice process. Depending on your role in the clinical environment you may possess some of the skills needed, but not all. Nurses generally understand the key concepts of evidence based practice but might lack basic literature searching skills. Student nurses learn about the importance of evidence-based practice while studying; however, until they become practicing nurses, they might not fully understand the correlation between evidence-based interventions and improved patient outcomes. 

What is evidence-based nursing practice and why is it important?

Evidence-based nursing is a process founded on the collection, interpretation, appraisal, and integration of valid, clinically significant, and applicable research. It is not about developing new knowledge or validating existing knowledge, but rather translating existing evidence so that it can be applied to clinical decision making. The expected standard in modern healthcare systems, evidence-based nursing practice links research and theory to practice, providing clinicians with current, reliable research driven data to guide patient care decisions.

Research has shown that patient outcomes are substantially improved when health care is based on evidence from well-designed studies versus tradition or clinical expertise alone. Better patient outcomes lead to more efficient performance, which is crucial for hospitals with staffing challenges.

What is the PICO process? 

PICO is a format for developing a good clinical research question prior to starting one’s research. It is a mnemonic used to describe the four elements of a sound clinical foreground question. The question needs to identify the patient or population we intend to study, the intervention or treatment we plan to use, the comparison of one intervention to another (if applicable) and the outcome we anticipate. These make up the four elements of the PICO model: Patient / Problem, Intervention, Comparison and Outcome. 

The PICO process starts with a case scenario from which a question is constructed that is relevant to the case and is phrased in such a way as to facilitate finding an answer. Once a well-structured question is formulated, researchers will be in a better position to search the literature for evidence that will support their original PICO question.

STEP 1: Formulate the PICO question

Case Scenario:

You are a Registered Nurse working on a Urology unit. One of your patients is a 55-year-old man who is recovering from abdominal surgery – specifically a laparoscopic prostatectomy. The patient complains of abdominal pain and nausea. His abdomen is distended, and he has no bowel sounds. The registrar suspects a paralytic ileus and confirms the diagnosis based on the combination of clinical features and imaging.

At the next Evidence-Based Nursing Practice Committee meeting, you discuss this case. The committee decides to do a case study to determine if there is evidence to suggest that a simple intervention such as chewing gum post-operatively can prevent a post-operative ileus following abdominal surgery.

Based on this scenario, our research question is: “In patients undergoing abdominal surgery, is there evidence to suggest that chewing gum post-operatively compared with not chewing gum post-operatively affects post-operative ileus?”

STEP 2: Identify keywords for each PICO element

Population (P) – What individual or group are we interested in studying?

Intervention (I) – What is the action (intervention, treatment) we are considering taking?

Comparison (C) – To what other action (intervention, treatment) are we comparing the considered action?

Outcome (O) – What do we anticipate as an outcome?

“In patients undergoing abdominal surgery, is there evidence to suggest that chewing gum post-operatively compared with not chewing gum post-operatively affects post-operative ileus?”

STEP 3: Plan your search strategy

Plan a search strategy by: 

  • Determining which database(s) to search 
  • Identifying the major elements of your question 
  • Translating natural language terms to subject descriptors, MeSH (medical subject headings), or synonyms

Synonyms, words or phrases that mean exactly or nearly the same as another word or phrase, can help expand your search appropriately. For example: when searching the keyword ‘surgery’, you might miss articles that instead describe a patient as ‘postoperative’ or in ‘recovery’. Adding synonyms will help to expand your results to those articles that are still relevant but might not include the words ‘abdominal surgery’. These are shown as ‘Search Strategies’ in the table below.

STEP 4: Execute the search

Before you begin your search, you will want to ensure the Search Mode is set to Boolean/Phrase. The reason this is important is because this option allows for “exact phrase” searching. For example, if you searched for the phrase, Heart Disease, the system will search for records where the two words "heart" and "disease" appear together, as a phrase, and not simply records where the two words appear separately.

To begin your search, first refer to Fig. 2 above. Each PICO Element (P, I, C, O) will be searched individually using the correlating Search Strategy. After each search, you will clear the screen and start a new search before beginning your next search.

  • P (Patient or Population): Begin your search with the Patient or Population, which are those patients undergoing abdominal surgery. As mentioned above, to increase your search results, try adding less descriptive terms that have the same meaning, such as Surgery, Postoperative or Recovery. *Note: Be sure to use the Boolean operator, “Or”, so that each result contains at least one of these search terms. Fig. 3 is an example of this search strategy shown on the EBSCOhost platform used in CKN's discovery search and CKN databases such as CINAHL Complete, MEDLINE Complete and PsycINFO.

  • I (Intervention): Start a new search for the Intervention, which is Chewing Gum or Gum. Be sure to use the Boolean operator, “Or”. Note the number of results.
  • O (Outcome): You can now conduct a search for the Outcome, which is post-operative ileus. Add the synonyms paralytic ileus or ileus. Your goal is to determine whether chewing gum postoperatively affects postoperative ileus, positively or negatively. Click search and note the number of results.
  • Combine searches: To complete your search, you will combine the Population (those patients undergoing abdominal surgery); the Intervention (Chewing gum) and the Outcome (Post-operative ileus/paralytic ileus). By using your database’s Search History, you should be able to combine these searches into one search showing results from all three of your previous searches. 

STEP 5: Refine your results 

You can now refine you results by adding limiters. Applying limiters to your search will allow you to focus your results to the most pertinent and relevant content ensuring that you aren’t wasting time wading through content that may not be useful.

For example, you may wish to limit your results by Date and Type: 

Published Date – Use this option to search for articles within a specified date range.

Evidence-Based Practice – You may wish to limit your articles to only those which are evidence-based. When searching an EBSCOhost database for example, the Evidence-Based Practice limiter searches the Special Interest field for the value “Evidence-Based Practice.” Applying this limiter allows you to limit results to: 

  • Articles from evidence-based practice journals 
  • Articles about evidence-based practice 
  • Research articles (including systematic reviews, clinical trials, meta analyses, etc.) 
  • Commentaries on research studies (applying practice to research) 

Should you find that you are left with too few articles by limiting your results to Evidence-Based Practice, you can instead choose any or all of the following publication types: 

Meta-Analysis: A systematic review that uses quantitative methods to synthesise and summarise results.

Systematic Review: A summary of the medical literature that uses explicit methods to perform a comprehensive literature search & critical appraisal of individual studies.

Randomised Controlled Trial: Participants are randomly allocated into experimental or control groups & are followed over time for the variables/outcomes of interest.

Cohort Study: Identifies participants who currently have a certain condition or receive a treatment and are followed over time & compared with another group of people who are not affected by the condition.

Case Control Study: Identifies participants who have a certain outcome (cases) & participants without that outcome (controls).

Case Report/Case Series: A report on one or more participants with a particular outcome.

(Adapted from CEBM - Centre for Evidence-Based Medicine)

STEP 6: Review the literature 

Once you have added limiters to your combined search and run the results again, choose and review articles that are most relevant to your PICO question. Should you find an article that is particularly relevant to your search but is not available to you in full text, check with your hospital library to see if they can locate the full text of the article for you.

STEP 7: Determine the level of evidence

The final step to the perfect PICO search is to determine the level of evidence within each relevant article. In searching for the best available evidence, a hierarchy exists regarding the level and strength of evidence (see Fig. 4). As you review the journal articles, select those that are based on highest level of evidence, such as a Meta-Analyses or a Systematic Review.


Fostering a culture of evidence-based nursing practice within a hospital in no easy task. It involves the integration of clinical expertise, patient values, and the best research evidence (Sackett D, 2002). The actual search for high quality clinical research evidence can be overwhelming to many. By using the PICO format, the search process will be streamlined and will yield the best available evidence to support clinical decisions and explore alternative treatments and procedures.


1. Conner, Brian T. (June 2014). Differentiating research, evidence-based practice, and quality improvement. American Nurse Today, Vol. 9 No. 6. 

2. Houser, J. (2018). Nursing Research: Reading, Using And Creating Evidence. Burlington, Massachusetts: Jones & Bartlett Learning. 

3. Melnyk, B.M. (2011). Evidence-based practice in nursing & healthcare: A guide to best practice. Philadelphia, PA: Lippincott Williams & Wilkins. pp. 3–7. 

4. Schub, E. B., & Walsh, K. C. (2017). Evidence-Based Nursing Practice: Implementing. CINAHL Nursing Guide. 

5. Yensen, J. (2013). PICO Search Strategies. Online Journal of Nursing Informatics (OJNI), 17 (3).


Adapted from the EBSCO CINAHL Complete white paper, “7 STEPS TO THE PERFECT PICO SEARCH: Evidence-Based Nursing Practice” by Kathy A. Jensen, MHA, RN. Kathy serves as the Medical Client Services Manager for EBSCO Health and is responsible for medical/nursing point-of-care database education and training of customers throughout the US and Canada. She has more than 25 years of experience in healthcare management/operations and medical information technology (sales, product management and training) and her clinical background includes CSICU, CV Surgery and ED. She is a Registered Nurse, Health Care Risk Manager and holds a Master of Science Degree in Healthcare Administration.