Get it straight from the start

 Over more than a decade Archimedes has presented clinical queries and the appraisal of the evidence that emerges. leading on to a clinical conclusion to the dilemma. What is strikingly common is that many questions can start in a muddle, and a failure to get an ‘evidence based answer’ might be a failure to ask an accurate question.

A recent trans-disciplinary teaching session had one anaesthetist summarise the whole of EBM question formulation as “Does drug A compared to drug B make outcome X happen more or less in patient group Z” … a brilliant anagram of the ‘PICO’ formula into Intervention, Comparator, Outcome, Patients. Now if your question doesn’t fit, or can be fudged to fit, this, then you need to unpack it.

Is it a diagnostic test? Try “Does super-TB-detector kit compared with Proper Microbiological Stuff indicate the presence of MTB infection in patients with proper immune systems?”. Prognostic features? “Does the presence of clinical choroamnionitis make it more likely that NEC will occur in this premature neonate?”.

Complex questions – like ‘What’s the best diagnostic test for leukaemia?” – can drive you either to textbook style review articles, whose statements you can then EBM-ise, or allow you to list a series of subquestions (Full blood count? Film? 6-colour flow cytometry?). Others – like “Should I do a CT before LP in teenagers?” might collapse into a series of queries (clinical features vs. LP features on raised ICP? might stop you needing to ask how good is CT at ruling out raised ICP).

Now if you get your PICO (or ICOP) straight from the start you’ll be well on the way to finding evidence based answers to the evidence based question you’ve decided upon.

– Archi

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