The promise of and problems with evidence-based medicine for paediatric asthma management.

The concept of 'evidence-based medicine' has now been in widespread use in clinical practice for over a decade. There are different types of clinical study, which may provide evidence on which to base clinical decisions, but some are much less robust than others. In making decisions about treatment, one of the highest levels of evidence in primary research is the randomized controlled trial. This study design has been used in clinical research for over 50 years. Systematic reviews of randomized controlled trial are scientific studies that review, critically appraise and, where appropriate, aggregate results from a number of different randomized controlled trials. They are increasingly being used throughout health care to provide guidance about treatment. Under the auspices of The Cochrane Collaboration, systematic reviews of randomized controlled trials are being conducted across the whole of health care. One of the most active areas for this work is within the field of asthma and clinicians are now able to access a large number of different systematic reviews on The Cochrane Library. If used appropriately, they can aid the clinician in making decisions about individual patients and provide a sound evidence base from which clinical guidelines can be developed.