Levels of Evidence

Abstract

This month we are introducing something new to the Journal, which I hope will add to the enjoyment for you, the readers. I have on a few occasions mentioned the importance of evidence-based approaches in urology. In addition, we have frequently heard the chairman of the various guideline committees describing the levels of evidence for their decisions. I have often felt that the level of evidence supplied by a paper should be printed after the abstract of the printed paper in our Journal, to help the readers formulate their ideas as to the value of the paper, and to help the guideline committees with their decision-making [1]. I would also refer you to an excellent comment which appeared in last month’s issue of the BJU International on this topic, by Dahm and Preminger [2]. They address several issues relating to such a policy and it is helpful to use their comment as an introduction because it explains much of our thinking behind it. For example, the decision as to the levels of evidence will be made by Mark Emberton, a newly appointed Associate Editor, who has appropriate training in these methods. The rating only provides a rough guide to the quality of the study and it is not intended to represent a decision that cannot be argued or defended by authors or readers. In fact, we would very much welcome your input on this; please write to us to let us know what you think of the idea, and whether you agree with our decisions. My idea to provide levels of evidence for each paper, echoed by Dahm and Preminger [2], is to act as a helpful aid to the reader, not as an attempt to sit in public judgement on authors or their work. Even papers with the highest quality of evidence might have limited clinical relevance, and in the field of urological surgery it might not be possible to carry out a randomized clinical trial on a particular surgical technique that might actually be of the highest clinical importance. It is important to bear both of these ideas in mind. I have included the Oxford Centre for Evidence-based Medicine ‘Levels of Evidence’ to follow this editorial comment, and this will appear at the end of each Journal issue in the future as a ‘ready-reckoner’. We have introduced this level-of-evidence rating in this month’s issue, but not on every paper because many have already appeared on-line in their final form. It will therefore be gradually introduced for every paper over the coming months. I hope you will approve of it. OXFORD CENTRE FOR EVIDENCE-BASED MEDICINE: LEVELS OF EVIDENCE (MAY 2001) A: consistent level 1 studies B: consistent level 2 or 3 studies or extrapolations from level 1 studies C: level 4 studies or extrapolations from level 2 or 3 studies D: level 5 evidence or troublingly inconsistent or inconclusive studies of any level ‘Extrapolations’ are where data are used in a situation which has potentially clinically important differences from the original study situation. Permission received from the Oxford Centre for Evidence-based Medicine to reproduce Levels of Evidence Model. Levels of Evidence produced by Bob Phillips, Chris Ball, Doug Badenoch, Sharon Straus, Brian Haynes, Martin Dawes.