CAN gambling with other people's children:

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, though 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 They make no attempt to statistically aggregate the data, nor search the grey, unpublished literature.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 searching² 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. (http://www.cebm.net). 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), books by Sackett et al⁴ and Moyer et al⁵ 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.

Electronic‐only topics that have been published on the BestBets site (www.bestbets.org) and may be of interest to paediatricians include:

When is a second course of indomethacin effective for PDA in neonates?

Does delayed cord clamping prevent sepsis?

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:

In children aged <3 years does procalcitonin help exclude serious bacterial infection in fever without focus?

Does avoidance of breast feeding reduce mother‐to‐infant transmission of hepatitis C virus infection?

Should children under treatment for juvenile idiopathic arthritis receive flu vaccination?

CAN gambling with other people's children: When we use tests to “rule out” a condition, we generally accept that we are left with a small risk of being wrong. (I think we have all discharged a child with an “upper respiratory tract infection” on a Friday to be greeted with them on antibiotics for pneumonia the following Monday.) How much faith we place in a test result is a product of two things: our initial assumption about the likelihood of the diagnosis (pretest probability) and our opinion as to how effective the test is (accuracy), but our actions do not just reflect these factors.

For instance, a well, afebrile child with a scattering of petechiae over its wrist 8 hours before, is unlikely to have meningococcal disease. If you perform a couple of tests, you can find that it has a low C‐reactive protein and a normal full blood count. What we do with this varies widely; some people would treat this with 48 h of antibiotics, others would discharge the patient home.

It is interesting to reflect on two things: first, what chance of meningococcal disease would you put on this clinical picture (before the test), and what about with the test results? What about your colleagues? You may be surprised by how widely this varies. Second, even those who have the same estimates of risk of disease may have different preferred actions (depending on their attitude to risk).

In looking at the diagnostic test for the ruling out of a disease, we can make our arguments more useful by having some data on the assumptions we make, and then transparently discussing our attitudes to risk. It is only after doing this that we can really decide if a test is good enough for us, regardless of how accurate it might be.

References: 1Moyer VA, Ellior EJ. Preface. In: Moyer VA, Elliott EJ, Davis RL, et al, eds. Evidence based pediatrics and child health, Issue 1. London: BMJ Books, 2000.

2Richardson WS, Wilson MC, Nishikawa J, et al. The well‐built clinical question: a key to evidence‐based decisions. ACP J Club 1995;123:A12–13.

3Bergus GR, Randall CS, Sinift SD, et al. Does the structure of clinical questions affect the outcome of curbside consultations with specialty colleagues? Arch Fam Med 2000;9:541–7.

4Sackett DL, Starus S, Richardson WS, et al. Evidence‐based medicine. How to practice and teach EBM. San Diego: Harcourt‐Brace, 2000.

5Moyer VA, Elliott EJ, Davis RL, et al, eds. Evidence based pediatrics and child health. Issue 1. London: BMJ Books, 2000.