A well formed clinical question covers the following 4 areas identified by the acronym PICO.
Patient or population or problem
Intervention or exposure or prognostic factor
Comparison (not always included)
Applying PICO to a Sample Question
Will an adult patient with sleep bruxism find that an occlusal splint reduces jaw muscle discomfort?
Patient / population / problem: Adult with sleep bruxism
Intervention: Occlusal Splints
Comparison: No treatment
Outcome: Reduce pain
Clearly articulating all parts of the question will help you conduct a comprehensive search.
Make sure that words for each part of the PICO question are in the search:
Adult AND Sleep Bruxism AND Occlusal Splints AND Pain
Searching is an iterative process. The results from your first set of search terms can help you identify additional related terms:
Adult AND Sleep Bruxism AND (Occlusal Splints OR Mandibular Advancement) AND (Pain OR Headache)
Categories of clinical questions
Etiology / Harm: identifying associations, risk factors and causes of a disease
Diagnosis: selecting tests that accurately detect a disease
Therapy / Prevention: selecting effective interventions to treat or prevent a disease
Prognosis: predicting the probable outcome of a disease or treatment
Sample questions for clinical question categories
Etiology / Harm: Are teenagers who frequently drink soda at risk for developing dental caries?
Diagnosis: What is the best method that dentists can use to identify early carious lesions?
Therapy / Prevention: Should teenagers and young adults with asymptomatic impacted wisdom teeth have them removed?
Prognosis: How long will a dental implant last in an adult patient with no periodontal disease?
Study design methods for clinical question categories
Researchers select the study design to match the kind of clinical question being asked and the level of knowledge about the question that already exists. Identifying the type of question being asked and the type of research that would best answer the question will help you focus the search on the highest level of evidence.
Etiology / Harm: Randomized control trial, cohort, case-control, cross-sectional
Diagnosis: Comparison to a reference standard with report of sensitivity/specificity
Therapy / Prevention: Randomized control trial, cohort, case-control, case series
Prognosis: Cohort, case-control, case series
If you are interested in more detailed explanations about these concepts, the CE tutorial from Proctor & Gamble is a good online source.