How to construct a good question

Your question will generally contain a problem that you are faced with, choices that you have to make in order to manage that problem, and an objective measure of outcome.

Formatting your question correctly is important in ensuring that your search for evidence is structured, systematic and complete. For example, if you want to know whether to implement a practice-wide policy to stop giving routine antimicrobial cover for ovariohysterectomy in dogs:

  • your problem would be ovariohysterectomy in dogs;
  • your choices would be routine antimicrobial use versus no routine antimicrobial use;
  • your objective measure (or outcome) could be post-operative infection rates (although other outcomes could be considered).

In order to ensure that the questions you are asking contain all of the right elements to provide you with the evidence, there are several ways you might choose to format your clinical question. Using a specific format for your question should help you to facilitate your search and ensure that your question is answerable.

In practicing EBVM, you may come across many different ways of formatting your question in terms of problem, choices, outcome and other limits on the answers you seek (e.g. you may come across interesting acronyms such as PICO, PICOS, SPICO, and PICOT, or you may be interested in addressing questions pertaining to clinical audits, etc.).

The most common way to format a question is to use the PICO system, focussing on the:

  • P – Patient: population and/or problem
  • I – Intervention: treatment, prognostic factor or exposure
  • C – Comparator: comparison or control
  • O – Outcome

We will focus on the PICO system in this resource, and will now look at each of the elements of PICO in more detail.