Chapter 4: Formulating PICO Questions

Summary

Guidelines help answer questions about clinical, communication, organizational or policy interventions, in the hope of improving health care or health policy.1 It is therefore helpful to structure a guideline in terms of answerable questions with relevant outcomes. Research questions that are too broad may necessitate extra resources to conduct the review, leading to heterogenous results that may be difficult to interpret. However, a broad question may produce a holistic summary based on a larger body of evidence and more generalizable findings. In contrast, narrow questions may require less resources but could lead to a smaller body of evidence with less generalizable findings. Depending on the scope of the review, authors should decide if it is more beneficial to lump things together resulting in a broader PICO question or if it is more useful to split comparisons and create narrow PICO questions.2 To define the scope of the review, research priorities should be identified, and stakeholders should be engaged. The scope of the review may focus on a setting in which a vaccine is introduced where there was no vaccine previously or in a setting where a new vaccine is being compared to an existing vaccine. The scope may also be focused on new or updated recommendations for existing vaccines based on a changing epidemiology and/or the populations affected. For more information about developing a PICO question for a systematic review, refer to https://training.cochrane.org/handbook/current/chapter-02.2

The GRADE approach can be used to answer various questions that lead to actionable recommendations.3 Research questions can be categorized as either background or foreground questions.1 Background questions provide context and frame the need for the guideline, while foreground questions directly inform recommendations. Therefore, background questions can provide information on the prevalence or burden of a problem that help formulate foreground questions. Foreground questions provide insight on harms and benefits of the intervention of interest while also considering factors like acceptability and feasibility. Good questions target topics with controversy or doubt surrounding the answer, help pave the way for future research and positively impact patient care, costs and quality of life.

Research questions act as the starting point for formulating recommendations; they help inform inclusion and exclusion criteria for included studies, shape search strategies, inform the type of data to be extracted and guide the wording for recommendations.3 Research questions may also inform the type of data synthesis used in a review. In order to create strong research questions that shape an evidence review, questions should be developed and presented using the PICO (population/intervention/comparator/outcome) framework.1 The population component of the question describes the target population for the intervention. The intervention includes the treatment, test, policy or exposure being evaluated in the review. The comparator specifies the alternatives to the intervention being recommended in the guideline. Typically, a placebo is not used as a comparison in a recommendation (even though it may serve as a comparison in the systematic review of the literature), as "placebo" would not be a sensible option to recommend. Instead, the comparisons could look at existing alternatives, standard practice and no intervention (e.g., no vaccine in the situation when no vaccine has been previously available). Outcomes consider the potential benefits and harms of the intervention and should be patient centered. Table 1 provides two examples of well-formulated PICO questions.

Table 1. Examples of PICO Questions

When developing PICO questions for guidelines, the setting in which the recommendations will be applied is often taken into consideration in addition to elements specified in the PICO approach. Moreover, the identification of subgroups within the population part of the PICO question allows for guideline panels to create recommendations targeting specific subpopulations. In the case of multiple comparators within a PICO question, guideline authors may need to clarify if the intervention is recommended over all the comparators equally or if there is a hierarchy. Additionally, PICO questions for guidelines may have a more comprehensive list of outcomes compared to a systematic review since they need to consider harms and how the implementation of an intervention may impact different populations. When listing outcomes for a PICO question informing a guideline document, the importance of the outcomes should be rated before the evidence review begins.