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Editorial

EQUINE VETERINARY EDUCATIONEquine vet. Educ. (2001) 13 0) 2-3

Evidence-based medicine: can it be applied to equineclinical practice?

Why the clinician should publish

As we continue in this issue of Equine VeterinaryEducation the series on "Why the clinician shouldpublish", it is pertinent to consider the relativeimportance of published articles to the veterinarianin decision-making in everyday clinical practice.Effective veterinary clinical practice hasalways drawn upon both science and art. Manyof the decisions that a clinician makes about thediagnosis or treatment of an individual animal (orgroup of animals) will be based on a combination ofthe information gained from clinical experience,undergraduate training, postgraduatetraining, reading of textbooks andprofessional journals, etc.

In this way, the clinician aims to base his or herdecisions and actions on the best evidence availableat the time. Why, then, js there a need to coin thephrase 'evidence-based medicine', and how doesthis differ from what has been practised anyway formany decades by clinicians?

Evidence-based medicine

Evidence-based medicine is the conscientious,explicit and judicious use of current best evidence inmaking decisions about the care of patients (Sackettet al. 1996). The practice of evidence-based medicinemeans integrating individual clinical expertise withbest available external clinical evidence fromsystematic research (Sackett et al. 1997). Individualclinical expertise comprises the proficiency andjudgement that individual clinicians acquirethrough clinical experience and clinical practice.Best available external clinical evidenceconsists of clinically relevant research, which mayarise from the basic sciences, but especially frompatient-centred clinical research.

There are 5 major reasons why the conceptof evidence-based medicine was developed inhuman medicine (Sackett et at. 1997). These samereasons could probably be applied equally toveterinary medicine; and specifically to equineveterinary medicine.

Firstly, new types of evidence (in particularrandomised trials and other rigorous clinicalinvestigations) are being created which can lead tomajor changes in the way that we care for our patients.

Secondly, it is clear that, although we need thisnew evidence daily, we usually fail to get it. This canbe caused by a lack of time necessary for keeping upto date, use of textbooks that are frequently out ofdate by the time they are published, and thedisorganised structure of journals.

Thirdly, and as a result of the foregoing, bothour up-to-date knowledge and our clinicalperformance tend to deteriorate with time.

Fourthly, traditional continuing educationprogrammes seem to be ineffective at improving ourclinical performance. Studies that have assessed theefficacy of traditional, instructional continuingmedical education have shown that it fails to modifythe clinical performance of participants and isineffective in improving the health outcomes ofpatients (Davis et al. 1995).

Fifthly, a different approach to clinical learning('evidence-based medicine') has been shown tokeep practitioners up to date.

Research

Any serious movement towards evidence­based veterinary medicine requires that a largebody of high quality patient-centred research bemade available to veterinarians willing and able toaccess and critically appraise the quality andapplicability of clinical trials (Keene 2000). Inequine medicine, such studies are unusual. Onemajor reason for this is the high cost of performingthese studies. The veterinary pharmaceuticalmarket represents only a tiny fraction of the entirepharmaceutical industry; and the industry is,therefore, unlikely to conduct studies whose costscould exceed potential returns. Despite thisproblem, useful and relevant studies in equinemedicine can be achieved on relatively smallbudgets. However, it is of vital importance that theclinician reading the published study is able torecognise and appreciate both the advantages and

T. S. Mair

limitations inherent in the evidence generated by avariety of clinical trial designs. The criticalappraisal of external evidence has 2 steps: decidingwhether it is valid (close to the truth) anddeciding whether it is important (and thereforepotentially important to you as the clinician).

A classification system for research studiesthat reflects the probability that theconclusions and recommendations of thestudy will be reliable has been proposed(Yusef et al. 1998).

• Class A: The most reliable evidence (Class A) isobtained from the results of systematic reviews(e.g. meta-analyses) of multiple, randomised,blinded, placebo-controlled trials designed toaddress the clinical questions of interest. Thisevidence is currently unavailable in veterinarymedicine because too few trials of this naturehave been performed. Individual blinded,placebo-controlled, randomised clinicaltrials also provide Class A evidence, but suchevidence is obviously not as strong as thatobtained from systematic reviews. Unfortunately,published individual blinded, placebo-controlled,randomised trials are also few and far between inequine medicine.

• Class B: Nonrandomised clinical trials usinghistorical controls provide significantly lessreliable evidence (Class B evidence) thanrandomised trials. However, these trials are morelikely to be performed in veterinary practice, andthe results should be examined critically. Ingeneral, positive results from a therapeutic trialutilising historical controls should be interpretedto mean that the therapy evaluated might holdpromise, and a randomised controlled trial isneeded (Keene 2000). Negative results from suchtrials are more likely to be true.

• Class C: Class C evidence is obtained fromuncontrolled case series. Evidence obtained fromsuch studies can be difficult to assess, and thereare many examples of therapies that wereadopted following positive reports from large caseseries that were later shown to have no benefit oreven to cause harm (Spilker 1996).

• Class D: The final category of evidence (Class D)is obtained from expert opinion, and/orextrapolated from basic research. This evidenceis considered to be the least reliable.

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Unfortunately, such evidence is the most widelyavailable source in veterinary medicine atpresent. This evidence is important and mayoften be correct, but it should if possible be testedby controlled clinical trials.

Conclusion

Continuing education journals, such as EquineVeterinary Education, rely heavily on expert opinion.Such opinion, and its assessment by the peer reviewsystem, is valuable and provides meaningfulguidance in the absence of more reliable scientificevidence. However, readers need to be aware of thepotential limitations of such information. Hopefully,as we progress into the new century, more reliableevidence will become increasingly available, and it isthe intention of the editors of Equine VeterinaryEducation and Equine Veterinary Journal thatsuch evidence will be made available throughthese pages.

T. S. MAIREditor, Equine Veterinary EducationBell Equine Veterinary Clinic,Mereworth, Maidstone,Kent ME18 5GS, UK

References

Davis, D.A, Thompson, M.A., Oxman, AD. and Haynes,RB. (1995) Changing physician performance. Asystematic review of the effect of continuing medicaleducation strategies. J. Am. med. Ass. 274, 700-705.

Keene, B.W. (2000) Towards evidence-based veterinarymedicine. J. vet. intern. Med. 14, 118-119.

Sackett, D.L., Rosenberg, W.M.C., Gray, J.A.M. andHaynes, RB. (1996) Evidence-based medicine: what itis and what it isn't. Br. med. J. 312, 71-72.

Sackett, D.L., Richardson, W.S., Rosenberg, W. andHaynes, RB. (1997) On the need for evidence-basedmedicine. In: Evidence-based Medicine. How to Practiceand Teach EBM, Churchill Livingstone, New York.pp 1-20.

Spilker, B. (1996) Guide to Clinical Trials, Lippincott­Raven Publishers, Philadelphia.

Yusef, S., Cairns, J.A, Camm, AJ., Fallen, E.L. andGersh, B.J. (1998) Evidence-Based Cardiology, BMJPublishing Group, London.