Using Clinical Trial Results
Posted by Dana Lawrence
Even the best randomized clinical trials cannot tell us for whom a given treatment is better, only that a given treatment is better than what it is being compared to. When we then read that trial after it has been published, we have to make a determination about whether or not we can apply it to our patient or to our specific set of circumstances. How can we go about doing so? Alejadro Jadad, developer of an instrument used to assess the quality of randomized trials, offers some thoughts on this (1). He suggests we consider the following:
- Does the research question match your own question? This is critically important. All research studies should provide you the question, which should also speak about the characteristics of the participants, the condition, the setting, the interventions, and the outcomes. It is surprising how many papers never actually present the actual question, but force you to read over the methods to determine what exactly is being studied.
- Does the report include enough information on the execution of the study? This will help tell you how well it was executed and whether or not you are comfortable that the researchers could answer the question they have asked. Issues to consider include:
(a) What was the sampling frame? How were prospective patients approached by investigators? We wish to know something about the population; there is a difference, for example, between patients seen in emergency room settings and those in private practice settings. The question about how patients were approached gets at the population sample and it generalizability: was this a convenience sample, a random sample, or something else.
(b) What were the inclusion and exclusion criteria? Again, this is to address issues of external generalizability. This gives information on the health status of participants, potential co-morbidity, etc.
(c) Was the setting appropriate? Was it similar to your own setting? See above; some settings have patients bases significantly different from the ones you see in practice, and as a result you may not feel comfortable generalizing the information from the study results to your own patients.
(d) What were the interventions and who gave them? We see many trials involving spinal manipulation, but certainly not all are provided by chiropractors. Some might have been given by physical therapists, whose training, philosophy and approach differs from ours. Thus, perhaps we are less comfortable in generalizing results.
(e) Was there randomization and blinding? This helps ensure less bias in results and better comparison between groups.
(f) What were the outcomes of interest? This gets at whether or not you can use the results to inform your own patient management question. These should matter both to you and to the patient ( a so-called “patient-oriented evidence that matters” or POEM).
This approach can help you determine whether or not the paper you are reading can be used to help decide what to do with the patient you are caring for. Jadad nicely illustrates these points in his informative little book.
- Jadad A. Randomised controlled trials. London; BMJ Books, 1998:69-73
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