This article is part of a series on Critical Reading.
Where do you start when trying to judge papers in medical journals? All too often we are in a hurry and glance briefly at the title and then the conclusion of the abstract. However I would suggest that you try to get inside the mind of the writer of the article; try to work out why they carried out this piece of work. It is easier to do this if you have a structure to work to and I suggest using a four part question at this point.
- What are the characteristics of the Patients in the trial?
- What is the Intervention being studied?
- What is it Compared with?
- What Outcomes are measured?
Take a piece of paper and jot down the answers to the four questions shown in the box and you will have a neat summary of the question that your paper is trying to answer. You should have a note of the characteristics of the patients in the trial, the main intervention studied, what it was compared with and what outcomes were measured. You can remember the headings using the acronym PICO (Patient, Intervention, Comparison, and Outcome).
Is this an important question?
If you have been able to identify the four parts of the question that the paper is trying to answer the next thing to ask yourself is whether the answer is going to be relevant to you and the patients that you are looking after. Much research is driven by academic or industrial interest and the question may not be relevant to you.
All too often the outcomes chosen are surrogates that are easy to measure but may not reliably indicate whether the treatment will be of real benefit to the patient. Also the comparison may be with the wrong alternative treatment, or the patients in the trial may not be representative of those seen in your practice. Two examples may help to illustrate the point.
Antibiotics for Acute Otitis Media
There is not shortage of randomised controlled trials that have compared one antibiotic with another for the treatment of acute otitis media, and this is an important issue for pharmaceutical companies introducing new antibiotics. However the first question to answer is whether any antibiotic is needed at all, and this cannot be assessed from comparing two antibiotics with each other. What is needed is evidence from trials comparing antibiotic with placebo to decide how much overall difference they make, and indeed the evidence from all identified trials of this type showed limited benefit of antibiotics balanced by side effects from the treatment. (1)
Nebulised Steroids in Asthma
Here again the crucial question is what nebulised steroids are compared with; the obvious alternative delivery method is using a spacer and metered-dose inhaler since the two delivery methods appear to be equally effective when used for delivery of beta-agonists in acute asthma (2). In spite of this there are very few randomised controlled trials that compare these two delivery methods for steroids. Nebulised fluticasone has been shown to reduce the requirements for oral steroids in severe asthmatics when compare with placebo, but to my mind this is not really the key issue. The costs of nebulised steroids are considerably more than using spacer delivery after all, so we need clear evidence of superiority against spacers not placebos in this instance.
In a nutshell
So in summary use the 4 part question to summarise what the paper is about and then decide if it is a question that is worth spending the time to read in more detail. Consider if the question is an important one and if it is you will then need to think about the validity of the research method used before taking too much notice of the results; this will be the subject of the next article in this series.
1. Del Mar C, Glasziou P, Hayem M. Are antibiotics indicated as initial treatment for children with acute otitis media? A meta-analysis. BMJ 1997;314:1526 –1529
2. Cates C J, Rowe BH. Holding chambers versus nebulisers for beta-agonist treatment of acute asthma (Cochrane Review). In: The Cochrane Library, Issue 2, 2000. Oxford: Update Software.