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Searching the Literature for Evidence-Based Answers: Ask


  • Use the details of the situation and the information you discover to provide searchable keywords.
  • Organize these keywords into a logical sequence as a way to clarify what you are trying to discover.
  • Use the keywords to create a clinical question that can be answered using evidence based information


Once you have considered all background information you have discovered for the scenario, it is time to start reviewing the terms you will use to search for information. 

The mnemonic used for organizing these terms is called “PICO.”

“PICO” stands for:

  = Patient, Population or Problem

  = Intervention

  = Comparison

  = Outcome

= Patient, Population, or Problem

Identifying the patient, population, or problem is important because not only does it identify the main subject of the search, but it also can include terms that will help focus your search more effectively. 

Frequently this will include a patient or population as well as the problem. For example, a 45 year old male with a chest cold. In this case the patient is a 45 year old male, and the problem is a chest cold.

When including terms in this section, be sure to include known facts about the main subject, such as the patient being a smoker or having a history of leukemia. 

I = Intervention

The intervention is defined as what action is being considered in the clinical scenario. 

Finding appropriate terms for the intervention may be part of your background research. 

In some cases, medications often have generic names, brand names, or may be in a similar pharmaceutical group as other medications. For example, if you are looking for information about Acetaminophen, you may either look for the brand name Tylenol, or the pharmaceutical group non-steroidal anti-inflammatory agents (“NSAIDs”).

C = Comparison

The comparison is what might be done instead of the chosen intervention. 

Frequently, the comparison listed will be whatever the gold standard or the usual practice is for the situation in question. 

Occasionally the comparison will be to take no action. For example, if a patient has a strained muscle, it will heal on its own. However, if you are using an intervention to speed up the healing process, then the term used for comparison when letting the muscle heal naturally may be "nothing".

You can enter the term “nothing” in the comparative section of the PICO. 

O = Outcome

The outcome listed should be something that can be measured, while describing what you want the results of your search to show.

The outcome should not be written as if it is predetermined. Instead it should be listed as a possibility from what may be presented by the evidence discovered. The outcome should include terms like "most effective", "least side effects", "most accurate", or other terms used to reflect measurements of the evidence.

(T) = Time

This element of the search that asks "how long"? This may include how long it takes for an intervention have an outcome, or how long something has to be observed. 

This is not always a component used to define a clinical or foreground question.

There are also other elements that sometimes may be included in the PICO mnemonic including:

(T) = Type of study

(T) = Type of question (these are discussed further in the next sections)

PICO search tips:

  • Use PICO to organize the terms you can use to search the literature.
  • When using these terms to search the literature, you may have to adjust terms to get more results. For example, instead of saying “10 year old,” try using either the term pediatric, child, or children.
  • If the Comparative is listed as “nothing”, unless you are specifically trying to find information about not doing something, it is usually best to simply not include a comparison search term when actually searching the literature.

Clinical Query

The clinical query is made up of all the elements of “PICO.” 

As an example, you would list the query as "In a middle age man with a history of heart disease who is having chest pains(Patient, Population, or Problem), is using garlic pills (Intervention) more effective at relieving symptoms (this is the Outcome) than nitroglycerin pills (Comparison)?"  

In most research, a clinical query would be the equivalent of a research hypothesis; however, in evidence-based practice, the clinical query is a tool that is used to determine what type of information you need.