The veterinary literature - what is important?
Prior to starting my residency I didn't understand what it meant to 'go down a rabbit hole' (in reference to reading of the veterinary literature). During my training however, I went down many rabbit holes. By this I mean I read and over-interpreted a lot of things that were not important. They looked important, and they were really interesting, however they were not going to help me pass my specialty examinations. My supervisor Dr David Cook persistently reminded me about the 'hierarchy of evidence' and this eventually guided my study. Luckily for me I did (finally) grasp this concept, because in what some would describe as a cruel (or happy) twist of fate, they directly asked about this on our 2022 exam - "Discuss the hierarchy of evidence". So what is the hierarchy of evidence? The answer is in the following posts. I've divided it mainly so I can use two cute photos of my cousin's pet rabbits. You are allowed rabbits as pets in NZ luckily for my cousin Claire (whose rabbits live in the house, not a cage!).
Evidence Hierarchy - what is it and why is it important? At the top, is the meta-analysis, which is a statistical analysis of the results of several studies on the same topic. Similarly, is a systematic review, which is a critical analysis of the literature to date on a topic (generally to answer a question). Just remember these are the best studies. When these reviews tell you the evidence isn't great, then you have to look further down the pyramid in order to make decisions or form opinions. Next, are randomised, controlled trials. Some researchers argue that a recent randomised, controlled trial, is even more useful than one of the above reviews. But basically, both are good and a higher degree of value should be put on the results. Next, are the observational studies - these are your cohort studies, case-controlled studies and cross-sectional studies. There are separate definitions for these, but basically they either prospectively or retrospectively examine groups of patients looking for trends, outcomes, risk factors etc. There is always inherent bias, however they can give useful information when there is little else to go by. Then, we have animal trials and vitro trials. These are often the most interesting, because they test a new hypothesis, idea or piece of equipment and they can spark interest or bring hope for new treatment ideas. Unfortunately, often when we take these initial ideas and apply them to a population of diseased animals, with a control group, the results may not stack up against the initial exciting work.
Then finally, at the bottom of the pyramid, are case studies and expert opinion. And you won't get many marks for these on an exam, and you would only use them for decision making if you had nothing else.
Does this mean studies at the lower end of the pyramid are not important research? no.
Does it mean they are less important for our day to day decision making and fellowship examination study? yes.
Why is the pyramid so important? because this is how we should make decisions - based on the best available evidence. This is what we took an oath to do, but it also helps you to cut down on a LOT of literature reading if you are studying for fellowships. I think this is probably why the examiners chose to ask about this on the 2022 examination. It is not possible to remember the 8000+ articles you probably have sitting in your endnote.
I'm hoping this information helps those studying to avoid rabbit holes. On the rabbit note, rabbits are banned as pets in QLD where I work (this can make for a great prank call at 5 minutes before closing to call and say you are bringing in your pet rabbit. Not that I would ever do such a thing....)
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