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- systematic review
- atopic dermatitis
- oscillatory ventilation
In order to give the best care to patients and families, paediatricians need to integrate the highest quality scientific evidence with clinical expertise and the opinions of the family.1Archimedes seeks to assist practising clinicians by providing “evidence based” answers to common questions which are not at the forefront of research but are at the core of practice. In doing this, we are adapting a format which has been successfully developed by Kevin Macaway-Jones and the group at the Emergency Medicine Journal—“BestBets”.
A word of warning. The topic summaries are not systematic reviews, through they are as exhaustive as a practising clinician can produce. They make no attempt to statistically aggregate the data, nor search the grey, unpublished literature. What Archimedes offers are practical, best evidence based answers to practical, clinical questions.
The format of Archimedes may be familiar. A description of the clinical setting is followed by a structured clinical question. (These aid in focusing the mind, assisting searching,2 and gaining answers.3) A brief report of the search used follows—this has been performed in a hierarchical way, to search for the best quality evidence to answer the question.4 A table provides a summary of the evidence and key points of the critical appraisal. For further information on critical appraisal, and the measures of effect (such as number needed to treat, NNT) books by Sackett5 and Moyer6 may help. To pull the information together, a commentary is provided. But to make it all much more accessible, a box provides the clinical bottom lines.
The electronic edition of this journal contains extra information to each of the published Archimedes topics. The papers summarised in tables are linked, by an interactive table, to more detailed appraisals of the studies. Updates to previously published topics will be linked to the original article when they are available.
Electronic-only topics that have been published on the BestBets site (www.bestbets.org) and may be of interest to paediatricians include:
What is the role of plain abdominal radiograph in the diagnosis of intussusception?
What is the significance of headache following head injury?
Is nebulised salbutamol indicated in bronchiolitis?
Are oral steroids beneficial in bronchiolitis?
Readers wishing to submit their own questions—with best evidence answers—are encouraged to review those already proposed at www.bestbets.org. If your question still hasn’t been answered, feel free to submit your summary according to the Instructions for Authors at www.archdischild.com. Three topics are covered in this issue of the journal.
Do oral antihistamines stop the itch of atopic dermatitis?
Is elective high frequency oscillatory ventilation better than conventional mechanical ventilation in very low birth weight infants?
Can surfactant cure babies with severe bronchiolitis?
Systematic reviews and meta-analysis
Systematic reviews of healthcare topics are seen by some as the “Holy Grail” of evidence based medicine. Just like the Holy Grail, there are a number of myths around systematic reviews, how they differ from a meta-analysis, and how they can be interpreted.
“Systematic reviews are the same as meta-analysis”
A systematic review is a study performed on previous research. It follows a simple structure: the setting of a focused question, unbiased collection of the best evidence to answer that question, appraisal of those studies found, and an overview of that information in context. Meta-analysis is a family of statistical techniques that combine the results of different studies into a single summary result. The underlying presumption is that all the studies are really telling us the same answer, and that by chance the results have differed. Combining them as though they were all one study makes us able to give a more precise estimate of the result. A systematic review might, if the data appear similar, use meta-analysis to produce an overall result. On the other hand, the review might favour giving a narrative conclusion. What’s also clear is that if a meta-analysis is performed without a systematic review, there is an increased risk of an incorrect result.
“Systematic reviews are of randomised controlled trials”
Systematic reviews have been largely of treatments. (The Cochrane database is almost all reviews of interventions.) In these reviews, the basic study design is a randomised controlled trial, as this is the least biased way of assessing the effects of an intervention. There are an emerging number of systematic reviews of other questions—diagnostic tests,1 prognostic variables,2 and even aetiological elements like genetic polymorphisms3 have been subject to this process.
“A systematic review is better than any other study”
Just like any other study, systematic reviews need critically appraising and their results interpreting in the context of their weaknesses. Even a well performed systematic review does not always give us the “right” answer: what it gives us is the current best guess. We should always be questioning, revisting, and reassessing our activity in the light of better evidence as it emerges.
Bob Phillips Evidence-based On Call, Centre for Evidence-based Medicine, University Dept of Psychiatry, Warneford Hospital, Headington OX3 7JX, UK;