3. Types of clinical questions

3. Types of clinical questions

To benefit both patients and clinicians, questions need to be focused and directly relevant to the patient or scenario at hand.

Ferret held in a handCategorising the type of your clinical question can help you to decide which study design would best answer your question and its level of evidence, which becomes important when you begin to appraise the evidence.

In the Appraise section, we will explore the different study types and the levels of evidence in more detail.

Clinical questions can be divided into five main topic areas, relating to:

  1. treatment
  2. prognosis and incidence
  3. aetiology or risk
  4. diagnosis
  5. prevalence.


These types of questions refer to treatment choices made about patients in practice. These choices can include drugs or medicines to be used, surgical methods, changes in diet or management, and many more. These types of questions are best answered by randomised controlled trials when they are available.

Example: Which diet is best to feed cats with chronic renal disease?

Prognosis and incidence

These types of questions relate to the likelihood of disease or the progression of disease over time. These questions are best answered by cohort studies.

Example: Does sex affect survival in flat-coat retrievers with cancer?

Aetiology and risk

These types of questions investigate the origin of disease or the factors influencing development of a certain condition or disease. These questions are best answered by cohort studies, case-control studies or cross-sectional studies.

Example: What are the risks of adverse events in general anaesthesia in ferrets under different protocols?


These types of questions involve identification of a disorder based on the animal’s presenting signs. These questions are best answered by diagnostic test validation studies (also known as diagnostic evaluation studies).

Example: Which diagnostic test is most reliable for diagnosing fascioliasis in dairy cattle?


These questions consider the frequency of disease at a certain point in time and are best answered by cross-sectional studies.

Example: What is the prevalence of cardiac disorders in Welsh Section A mountain ponies?

Stakeholder experiences, preferences and values

We can also ask questions about the experiences, values and preferences of the stakeholders concerned, which, while not necessarily clinical questions, are relevant to the more holistic practice of EBVM.

Stakeholder experiences, preferences and values questions consider a wide range of issues, and no one specific type of study is sufficient to address this general category. Both qualitative, quantitative and mixed method approaches drawn from both social and biological science modalities may be appropriate, and a full guide to this is currently beyond the remit of this course.