Applying evidence-based decisions in clinical practice (Proceedings)

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.

Quality of evidence guidelines adapted from the US Preventive Services Task Force also serve as an excellent example of a rigorous application of an evidence-based appraisal system.1,2,6 Guidelines categorize the quality of evidence into the following grades: I, evidence obtained from at least 1 properly designed, randomized, controlled study in the target species; II, evidence obtained from at least 1 properly designed, randomized, controlled study in the target species but performed in a laboratory or research colony setting; III. evidence obtained from appropriately controlled studies without randomization; evidence obtained from appropriately designed cohort or case-control studies, preferably from more than 1 center or research group; or dramatic results for uncontrolled studies (eg, results for taurine supplementation in cats with cardiomyopathy); and IV, reports of expert committees, descriptive studies, case reports, and opinions of respected experts developed on the basis of their clinical experience. Grades I and II are the evidence with the highest quality; that is, grade I and II studies are most likely to predict results seen in clinical practice.

Applying evidence to a specific patient

When data from clinical studies are available, several questions can be used to decide the applicability of evidence to nutritionally manage a specific patient.1,2 Were outcomes of the study clinically relevant? Are there differences between the animals in the study and my patient that may alter expected treatment response? Are there potential drug-nutrient interactions that may alter the expected treatment response? Are there differences in the nutrient contents of the food or supplements that may alter the expected treatment response? Is the food or supplement readily available and economically feasible? Is the nutritional intervention feasible in the owner's setting? What are the patient's likely benefits and risks from the various nutritional management options? How will the owner's values or patient's preferences influence the decision about nutritional management? Does the patient have other health conditions that substantially alter the potential benefits and risks of nutritional management?

Conclusions

Currently, veterinarians are taught to practice clinical medicine primarily on the basis of knowledge gained during their education and from continuing education programs, journals and textbooks, expert opinions, and their own experience of clinical success. These sources are usually relevant but often lack scientific scrutiny; frequently, these sources do not constitute the highest quality of evidence. In the future, veterinarians will increasingly need to understand the epidemiologic aspects of disease, apply clinical guidelines to specific patients, and discuss the risk-benefit probability with pet owners. Application of EBM to veterinary medicine clearly offers a new approach for making clinical decisions and managing patient care. Adopting guidelines for veterinary clinical practice that include elements of EBM and adapting them to each patient will likely improve patient outcomes.

References

1. Geyman JP, Deyo RA, Ramsey SD, eds. Evidence-based clinical practice: concepts and approaches. Boston: Butterworth-Heinemann, 2000.

2. Sackett DL, Straus SE, Richardson WS, et al, eds. Evidence-based medicine: how to practice and teach EBM. 2nd ed. Philadelphia: Churchill-Livingstone, 2000.

3. Cockcroft P, Holmes M. Handbook of evidence-based veterinary medicine. Oxford, U.K.: Blackwell Publishing, 2003.

4. Keene BW. Towards evidence-based veterinary medicine. J Vet Intern Med 2000;14:118–119.

5. Moriello KA. Introducing evidence based clinical reviews in Veterinary Dermatology. Vet Dermatol 2003;14:119–120.

6. Roudebush P, Allen TA, Dodd CE, et al. Application of evidence-based medicine to veterinary clinical nutrition. J Am Vet Med Assoc 2004;224:1766-1771.

7. Polzin D. Treating feline renal failure: an evidence-based approach, in Conference Notes. Western Vet Conf 2003.

8. Polzin D. Treating canine renal failure: an evidence-based approach, in Conference Notes. Western Vet Conf 2003.

9. Olivry T, Mueller RS. Evidence-based veterinary dermatology: a systematic review of the pharmacotherapy of canine atopic dermatitis. Vet Dermatol 2003;14:121-146.