The prevailing system of veterinary medical education and the practice of continued learning are not based on rigorous assessment
of evidence for or against particular management options, including many aspects of clinical nutrition. Journals and textbooks,
even those that can be rapidly accessed in the short time required to make clinical decisions, may not be helpful for determining
specific risks and benefits of nutritional management. Veterinarians often rely on clinical experience and judgment, perhaps
supported by the advice of colleagues or consultants who practice in a similar manner. Evidence-based medicine (EBM) represents a major, but still largely untested, intellectual advance when making clinical decisions and determining and patient
care.1-6
Concepts of EBM
EBM is defined as the integration of the best research evidence, clinical expertise, and patient values.2 Best research evidence
means clinically relevant research, especially from patient-centered clinical studies. Clinical expertise refers to the ability
to use clinical skills and past experience to rapidly identify each patient's unique health state, establish a diagnosis,
and determine the risks and benefits of potential interventions for that specific patient. Patient values include unique preferences,
concerns, and expectations each human patient brings to a clinical encounter and that must be integrated into clinical decisions
to best serve the patient. It was further believed that integration of these 3 elements would result in clinicians and patients
forming a diagnostic and therapeutic alliance that optimizes clinical outcomes and quality of life.
The concepts of EBM also apply to dogs, cats, and other nonhuman animals.3-9 The concept of patient values must be extended to include the unique preferences, concerns, and expectations of each owner
as well as those of their animals (ie, the patients). Regardless of the definition used, the intent is that use of current
best evidence does not replace clinical skills, judgment, or experience, but it does provide another dimension to the decision-making
process that also considers the patients and their owners' preferences.
A conceptual model for evidence-based clinical decisions reveals that the best clinical decisions are made when clinical expertise,
research evidence, and owner or patient preferences overlap.1-3 Clinical expertise is obviously needed to obtain a medical history and assess a patient's nutritional and health status.
Clinical expertise allows for the individualized care of a specific animal's needs. Owners have always exercised their preferences
for medical care by seeking second opinions, choosing alternate treatments, exercising economic constraints, and adhering
(or choosing not to adhere) to recommended therapeutic plans. Moreover, owners currently have greater access to clinical and
nutritional information than ever before.
The challenge of integrating clinical expertise with current best evidence from medical and nutritional research is complex.
Veterinarians usually attempt to base their decisions on the best evidence available. This evidence often represents extrapolations
of pathophysiologic principles, studies conducted in other species, and logical conclusions based on data derived from patients
in clinical studies. The advent and proliferation of randomized controlled clinical studies have led to an increase in the
quantity and quality of clinically valid evidence. When possible, veterinarians should use information derived from systematic,
rigorously controlled clinical studies to make diagnostic and treatment decisions. Evidence-based medicine or evidence-based
clinical nutrition does not always lead to a definitive answer, but it does provide a framework for making decisions and understanding
the risk-benefit relationship of various feeding or therapeutic plans. To better understand EBM, an understanding of the rules
of evidence is necessary.
Rules of evidence
Scientific evidence is the product of appropriately designed and carefully controlled research investigations. A single study
does not constitute evidence; rather, it contributes to a body of knowledge that has been derived from multiple studies investigating
the same area. Unfortunately, there is neither a central repository for clinical nutrition information nor only 1 system for
establishing quality evidence. Several classification schemes may be useful for establishing rules of evidence for recommendations
regarding clinical nutrition.
Traditional sources of evidence include materials such as textbooks, personal journal collections, conference proceedings
and clinical guidelines. Much of this evidence is not based on appropriately conducted clinical studies in the target species.
Many clinical and nutritional interventions are used because the basic pathophysiologic rationale made sense, even though
data on the true clinical outcome are lacking to document a positive effect. Sources regarded as strong evidence include randomized
controlled clinical studies or systematic reviews of more than 1 study (ie, meta-analysis). These are followed respectively
by epidemiologic studies (cohort studies or case-control studies), models of disease, and case series. The hierarchy of evidence
is based on the notion of causation and the need to control bias.
