How relevant is the evidence?

When you read a study, you must make a judgement about how similar your patient is to the population or sample being examined in that particular study, and whether that study is worth considering for the individual circumstances in front of you.

Since a perfect study examining the whole population of animals you are interested in will rarely exist (especially in veterinary medicine!), it is up to you to decide if the evidence you have found is pertinent to your individual clinical question. Studies are often conducted on a number of subject animals, and may therefore only be truly representative of a particular subset of a particular population of animals.

Some pertinent questions to ask may be:

  • Does the population of animals in the study represent the animals that you see (e.g. animals seen at referral practices versus first opinion practices)?
  • Does the evidence focus on animals with single morbidities (as opposed to animals with comorbidities)?
  • Does the evidence in the study focus on using one therapy versus combinations of therapies?

Thinking about how to apply the evidence from published studies to the individual animal, or group of animals, you are working with raises four different questions, as outlined by Del Mar et al. (2008):

  1. What are the potential effects of treatment, both beneficial and harmful?
  2. Are there differences in the effects of treatments on different sub-groups of animals?
  3. Are there differences in levels of risk between different groups/sub-groups of animals?
  4. How do the benefits and harms relate to the individual animal or group of animals you have in front of you?

CalvesWe will now illustrate these four questions using a clinical scenario about the use of analgesic products for calf dehorning.

1. What are the potential effects of treatment, both beneficial and harmful?

When making clinical decisions, it is important for veterinarians to weigh up the best evidence on both the benefits and harms of any interventions proposed.

Calf-dehorning example

2. Are there differences in the effects of treatments on different sub-groups of animals?

Certain sub-groups of animals (e.g. certain age groups) may be more likely to respond either positively or negatively to specific interventions. When thinking about how you might apply the evidence,  you will need to consider which sub-groups of animals were utilised in the research being considered.

Calf-dehorning example

3. Are there differences in levels of risk between different groups/sub-groups of animals?

By the nature of how and where they are kept, or their innate attributes, different groups or sub-groups of animals may have different levels of immunity and exposure to various pathogens. These differences may lead to different manifestations of disease severity in these different groups.

Calf-dehorning example

4. How do the benefits and harms relate to the individual animal or group of animals you have in front of you?

It is down to you as the veterinarian to make a judgement on the applicability of the research findings to your patients, which could involve a number of considerations. You might choose to reflect on your previous experience with similar cases, or to have a more in-depth discussion with the owner. You might also want to discuss the matter with colleagues, or consult an online forum to gain a broader view of the question at hand.

Calf-dehorning example

Another pertinent question to ask might be whether or not the findings of the studies are clinically relevant to your case, that is, will they really make a difference to the animal(s) in front of you? Once again, it is up to you to make a judgement about whether or not the outcomes measured would be expected to translate into meaningful clinical benefits to the patient and owner in front of you.

Calf-dehorning example

If you do not think the evidence from the papers you are considering is relevant enough to apply to the animal or group of animals you are treating, you can have a discussion with the owner of the animal(s) about the uncertainties around the options available (Legare 2009). Additionally you may choose to:

  1. Rely on the information in other forms of evidence such as textbooks, and online websites
  2. Do what you would normally do in these circumstances before you were aware of the published evidence, or
  3. Rely on your local clinic’s advice or guidelines or advice from colleagues who have handled these types of clinical problems before.
Calf-dehorning example