What type of clinical question are you interested in?

• Therapy/Intervention: For a disease or condition, will this treatment do more good than harm? How does it compare to other treatments?
• Etiology/Harm: What disease or condition could result from exposure to this potentially harmful thing?
• Prognosis: What is the patient’s likely clinical course over time and what are likely complications of a particular disease or condition?
• Prevention: Will this treatment or intervention modify the risk for developing a particular disease or condition?
• Diagnosis: How good is this diagnostic test at confirming or excluding a particular diagnosis?
• Quality of Life: What are the human elements in responding to or dealing with a disease, condition, or healthcare process?

The following tab will provide templates for developing your clinical question, depending on one of the above types.

In addition to the hierarchy of evidence, some clinical research study designs are more appropriate than others depending on the type of question being asked.

What type of clinical question are you asking? This will determine the most appropriate study design to look for in your database search results:

• All clinical questions: systematic review or meta-analysis (if available)
• Therapy/Intervention: randomized controlled trial
• Etiology/Harm: randomized controlled trial, cohort study, case-control study, case series
• Prognosis: cohort study, case-control study, case series
• Prevention: randomized controlled trial, cohort study, case series
• Diagnosis: independent, blind comparison to a gold standard
• Quality of Life: meta-synthesis, qualitative study (study designs such as grounded theory, ethnography, or phenomenology)

There is a hierarchy of clinical research evidence, depending on study design. The higher up the pyramid, quality of evidence is higher with more rigorous methodology and less risk of bias. Keep in mind that the hierarchy is not absolute. If you find a rigorously-conducted cohort study and a poorly-conducted randomized controlled trial on a similar topic, the cohort study would be higher quality. It is still up to you to critically appraise the evidence that you find.

The pyramid shows the following study designs in descending order, indicating quality of evidence, level of methodology rigor, and risk of bias:

• Systematic review or meta-analysis (evidence synthesis)
• Randomized controlled trial (experimental studies)
• Cohort study (observational studies)
• Case-control study (observational studies)
• Cross-sectional study (observational studies)
• Case report or study, case series, other descriptive or qualitative studies (observational studies)

PICO is a format that can be used to develop clinical questions.

• P = Patient/Problem/Population
  • Describe the patient, population, or problem of interest. This could include factors such as age group, ethnicity, diagnosis, co-morbidities, or setting (inpatient, outpatient, home care).
• I = Intervention/Exposure
  • List the main intervention that is being considered. This could include treatments such as drugs, surgery, or lifestyle modifications, or diagnostic tests.
  • For certain questions, there is not an intervention but rather an exposure being considered. This could include exposure to a harmful substance, risk factors, or protective factors.
• C = Comparison
  • List the main alternative to compare to the intervention or exposure (if applicable). This could include current standard of care or placebo.
• O = Outcome
  • List the main outcome(s) of interest. This could include resolution of symptoms, improvement in lab values, cost effectiveness, or quality of life.

The following are templates that can be used to develop your PICO question, depending on the type of clinical question you're asking:

Here are examples of PICO questions:

• Therapy/Intervention

  • In healthcare workers (Population), what is the effect of hand hygiene (Intervention) on the prevention of hospital-acquired infections (Outcome)? (In this example there is not a comparison concept.)

• Etiology
  • Are adults (Population) who have a history of smoking (Exposure) compared with those without a history of smoking (Comparison) at increased risk for lung cancer (Outcome)?
• Prognosis/Prediction
  • ​In patients who have experienced an acute myocardial infarction (Population), how does being a smoker (Exposure) compared to a non‐smoker (Comparison) influence mortality rates (Outcome)?
• Diagnosis or Diagnostic Test
  • In adults admitted to an intensive care unit for shock, (Population), is point of care ultrasound performed by a critical care fellow (Intervention) compared with echocardiogram by a cardiologist (Comparison) as accurate in evaluating left and right ventricular function (Outcome)?
• Meaning/Quality of Life
  • How do first-time mothers (Population) with premature infants admitted to a neonatal intensive care unit (Intervention) experience bonding with their infant (Outcome)?