LITMIR.BIZ

Figure 2.1.1 An evidence pyramid illustrating the variable reliability and risk of bias of different types of scientific evidence.

      Clinicians must always use their individual judgment in drawing conclusions from scientific evidence and applying these to specific patients. However, the hierarchy of evidence makes it easier for veterinarians to identify the reliability of specific types of evidence and of conclusions based on this evidence and to then communicate the degree of uncertainty to pet owners.

EXAMPLES

      Charlie is a 4‐year‐old neutered male Cavalier King Charles spaniel. His owner is seeking your opinion because another veterinarian recently told her Charlie has a heart murmur. The owner was told that because Charlie is young and has no clinical issues, there is no need to do any tests or start any treatment. However, her breeder has told her that Charlie should be on a medication called “enalapril.”

      You are aware of the breed predisposition for mitral valve disease (MVD) in Cavaliers, and you tell the owner that this is the most likely diagnosis based on Charlie's signalment and physical exam findings. You have also recently reviewed the American College of Veterinary Internal Medicine guidelines for diagnosis of MVD [1], and you explain that Charlie has stage B MVD, meaning he has a murmur but no clinical signs.

You explain that while enalapril was once commonly recommended for dogs with preclinical MVD based on low‐level evidence (pathophysiological reasoning and clinical experience), higher quality evidence (clinical trials) [2, 3] has since shown that it does not delay the onset of congestive heart failure (CHF), so you recommend against this medication.

      In association with another case, you recently investigated whether there are any useful treatments for dogs with stage B MVD. You discovered the EPIC study, a high‐quality clinical trial investigating the use of pimobendan in dogs with MVD [4]. This trial included a lot of Cavaliers, so you believe the results are applicable to Charlie. You tell the owner that this study found a dramatic delay in the onset of CHF in dogs using pimobendan if they were in stage B2 MVD, meaning they had enlarged hearts. You explain that you could stage Charlie using radiographs, but the EPIC study suggested measurements from an echocardiogram are more reliable, so you recommend this test.

      The owner is impressed with your detailed scientific knowledge and happy to have something she can do to keep Charlie healthy. You arrange an echocardiogram and agree to manage Charlie's MVD based on the results.

TAKE‐AWAYS

References

Recommended Reading