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Evidence-Based Everything

Making decisions is difficult. In health care, that is even more true, whether the decision affects policy or a patient, or whether it is a personal decision as to whether or not to have a treatment.

No health care system can satisfy all the possible demands made upon it, so decisions about allocating resources are very important. Resources should be allocated to those things that are effective, and withdrawn from those that are ineffective. The only way of judging effectiveness is through evidence.

That begs the question of what constitutes evidence. The types and strengths of evidence that may be available to us are shown in the box. Bandolier aims to bring, in the main, evidence of types I and II.

This issue of Bandolier has an example of type I evidence a report of a meta-analysis on quinine in nocturnal leg cramps. This is a good report which establishes that quinine is effective in reducing the number of cramps in elderly patients, and in giving them more pain free nights. Any criticism may stem from the fact that in six eligible reports, a total of only 107 patients were studied.

Another issue is how to put over a simple message about effectiveness. Bandolier has begun to favour the NNT approach, and, as promised last month, we have a worked example from a meta-analysis of RCTs curing H pylori infection in peptic ulcer. Using NNTs, it has been possible to compress the message down to a single sentence - "Using antibiotics to cure H pylori infections in 100 patients with peptic ulcer, compared to using a short course of conventional acid suppressing medicines, results in 90 patients cured of the H pylori infection, 20 extra ulcers healed at six weeks and 56 more patients whose ulcers remain cured at one year."

Finding the evidence is not always straightforward, and this month we have begun a series on "How do I find......? Those already expert in evidence-gathering may know this already, but for those of us who are still getting to grips with the complexities of modern information systems, Judy Palmer's series will be invaluable.

The quality of guidelines can vary from superb to very poor. Colin Blake reviews the evidence around the use of the Royal College of Radiologists guidelines on use of X-ray diagnostics.

Finally, evidence is not just about science or medicine. It is, or should be, also about management. Bandolier would love to carry examples of evidence-based management, or evidence about the effectiveness of different management methods.

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