Ask

5. Challenges to building a PICO

Scope versus volume of evidence

The Acquire section, coming next, explains more fully how you can use your PICO question to find the evidence.

Sometimes the question you ask may yield too much or too little relevant evidence. For example, you may find that your PICO has only yielded two papers, neither of which entirely answers your question. Assuming your search was conducted thoroughly, this may mean there is not enough evidence available to answer your question.

On the other hand, you may find that your search yields dozens and dozens of results, not all of which specifically relate to the problem or question you have in mind. In this case, it might be necessary to adjust your PICO to be narrower and more focussed in order to find only the most relevant evidence to answer your question. How you implement the evidence into practice will be further covered in Apply and Assess.

Choice of interventions and comparators

To cover all interventions, interests and comparators, multiple PICO questions need to be formed (often easier!) or you can choose a more general question. If you choose the latter, then you may end up with more evidence to sift through and the search outputs may become less relevant.

Multiple outcomes

Sometimes, a clear choice for your patient will only have a single objective desirable outcome, and it is certainly nice when this is the case in your clinical question. In reality, however, veterinary professionals often want to investigate a number of different outcomes for ourselves, our clients and our patients. For example, we may wish for a treatment that is effective, safe, easy to use and economic.

Many studies in the literature may address multiple outcomes, looking at both efficacy (e.g. survival times) and negative outcomes (e.g. adverse events) as well as costs, all in the same study. Sometimes you may need to look across multiple studies to gather these data; to do this, you will effectively be asking a series of PICO questions, all with different outcomes. One strategy is to refine your outcome to be a composite statement that reflects your overall aims for a case (e.g. ‘long-term survival whilst pain free’).