Type of question and the type of study are the two elements of a well-built clinical question. This can be helpful in focusing the question and determining the most appropriate type of evidence or study.
| Most common type of questions: | Type of study: |
| Diagnosis how to select and interpret diagnostic tests |
prospective, blind comparison to a gold standard or cross-sectional |
| Therapy how to select treatments that do more good than harm and that are worth the efforts and costs of using them |
randomized controlled trial > cohort study |
| Prognosis how to estimate the patient’s likely clinical course over time (based on factors other than the intervention) and anticipate likely complications of disease |
cohort study > case control > case series |
| Etiology how to identify causes for disease (including iatrogenic forms) |
cohort > case control > case series |