Introduction | Part 1: Hierarchy of Evidence | Part 2: Case Reports | Part 3: Cross-Sectional Studies | Part 4: Case Control Studies | Part 5: Cohort Studies | Part 6: Randomized Controlled Studies | Part 7: Meta-Analysis | Part 8: Systematic Reviews
During the last decade, profound changes in information technology have greatly influenced the methods by which we seek, acquire and integrate medical knowledge. The inherent expansion of this foundation of knowledge has generated a proliferation of new research, treatments and devices. In spite of this, there remains a gap between the discovery of new knowledge and its acceptance and adoption to routine practice .
This temporal delay from innovation to implementation averages 10-15 years (see translational medicine). Although human medicine enjoys a conspicuously larger number of systematic reviews and clinical practice guidelines based on current best evidence when compared to veterinary medicine, once this knowledge is finally adopted as a standard-of-care, it is not applied consistently by practitioners of either profession.
|Figure 1 (right): Distribution of the basic publication types in the evidence hierarchy, per year, in the veterinary literature from the years 2000-2010. While systematic reviews reside at the top representing the most rigorous and highest quality publication type, it resides at the bottom regarding the number of these important reviews published in the veterinary domain (click on image for full size view).|
The Internet has yielded an opportunistic and distributed expansion of this information. This includes the human and automated archival publication of abstracts and full text of print-based or online journals either after a given period of exclusivity in print as well as a growing number of open access publications such as PLoS One. The integration of related online resources using computer-based decision support tools allows the extraction of vital and novel information that normally would be difficult or impossible to analyze independently. For example, Epocrates, a formulary programmed for handheld computers, has detailed prescription drug information renewed daily by means of the Internet. The software is capable of recognizing multiple drug interactions or contraindications when given specific information about a patient's active problems.
Of considerable importance is the opportunity that clients (or patients) have to access the same information. They are empowered with similar decision support tools and are more than ever part of the healthcare equation. No longer is clinical decision making a one-way channel from clinician to client(patient). The human pediatric analogy often applied to veterinary medicine becomes even more fitting. Clients, who hold vital information about their pet's health, but often do not offer it because of miscommunication or a lack of understanding of its significance, are now better observers and analysts. They can enhance the ability of the veterinarian to make correct medical decisions. An owner of a diabetic cat who can easily access authoritative and inclusive articles about this disease online, is better prepared to monitor and recognize adverse events. They gain a greater understanding the role the veterinarian and diagnostic testing plays in approaching euglycemia and thus optimizing care.
Despite all this, the quality and quantity of evidence and the ability to understand the characteristics of different approaches to clinical trials and types of publications is daunting. Another challenge is the responsibility to formulate a sound question or query, search for it, determine what is clinically relevant, capture it, organize it, synthesize it and then implement it effectively. The fundamental concept here is clinically relevant information. What is relevant to one patient may not be relevant to another. An important skill is the ability to ask specific and appropriate clinical questions. Once a question is properly formulated, it may be used to develop a query of a medical database, a search engine or even applied to research.
This primer provides a basic overview of what is commonly referred to as the Evidence Hierarchy, an approach to explain the relative quality of publication types, their distribution (or lack thereof) in the veterinary literature. A discussion of related features, such as the curbside consultation, are discussed elsewhere since the nature of these consults may position its evidentiary value, starting at the bottom, variably in this hierarchy.
This series has been loosely organized from a set of lectures given by the author within graduate courses in Biomedical Informatics beginning in 2002. Content is being edited to improve organization, depth, correct inaccuracies as well as updates with new information during Winter/Spring 2012. Feedback is greatly appreciated. © 2011, Stuart Turner.