Have you ever been involved with a debate with a partner or colleague, travelling from one place to another, and when the course they took has got you to the destination safely, they turn to you and say “So, [add endearment here], you see my way was right.”? If you have, I doubt that you […]
Category: critical appraisal note
Risk vs. prognostic factors
The separation of ‘risk’ factors and ‘prognostic’ factors at first seems the sort of obsessive fine detail that gives epidemiologists and statisticians a bad name. Sadly, the difference is actually worth understanding for any clinician that’s going to try to cut through an observational study and understand what it might be truthfully telling us. (This […]
Confused by confounding.
Sometimes we are in situations where we think that something causes problems, and we can’t do a trial randomising one group to get something which we think causes problems! How do we then go about finding out – how to we avoid the problems of ‘confounding’ – and what is that anyway? For example, think […]
Relativist or absolute certainty?
If you were offered a choice of medication to treat an ailment you were suffering from, and you’d asked about how effective they were (and there’s a huge chunk of the population that wouldn’t, and would be happy to just do as they are told), then what information would you like? […]
Ask, and it might be given unto you.
The five steps of evidence based practice are commonly summarised as ‘Ask, Acquire, Appraise, Apply and Assess’. The first one of these – just asking a question – can prove terribly time consuming and difficult, but with a bit of dissection can be made much easier. The first step when deconstructing the anatomy of inquiry […]
Making science of art
In the window of the Wellcome Collection in London artists work to interpret and explain science: it’s an impressive experience to the irregular visitor. When faced with the presenting problems of a child & family, we are faced with trying to do the reverse. We have the sometimes inaccurate recollections of history, the variable responses […]
But at what cost?
It’s uncommon for us, as paediatricians, to be asked about how cost-effective our treatments are. Glancing at the media shows health stories about the new wonder drugs in adult cancer, or in Alzheimer’s disease, and how they are being restricted by a heartless and miserly health system. Where do these statements about ‘cost-effectiveness’ come from? […]
Disease spectrum vs disease prevalence
In examining a diagnostic test, we make the assumption that the characteristics of the test – its sensitivity and specificity (or likelihood ratios, the way I prefer to think) – will stay constant across different populations, although the positive and negative predictive values will change * . This is sort of true, and sort of […]
Crystal balls
It’s a great sport of journalists and commentators to look back at predictions of the future from decades past, and see just how badly they have gone astray. We do this as clinicians too, but with a sense of guilt … looking back to an unexpected relapse of a low-risk tumour, or a fulminant hepatitis […]
New things in evidence synthesis
The days of a meta-analysis being the simple adding up of lots of studies, pretending that they are all just tiny pieces of the One Big Trial that was performed before the world was made are on their way out. Newer ways of using synthesised evidence – like meta-regression and individual patient data analysis – […]