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Applying the results of trials and systematic reviews to our individual patients
  1. Sharon E Straus, MD1,
  2. Finlay McAlister, MD2
  1. 1University of Toronto Toronto, Ontario, Canada
  2. 2University of Alberta Edmonton, Alberta, Canada

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To translate evidence into clinical practice, clinicians need to judge how to apply the evidence to individual patients. For a complete discussion on how to assess the validity and applicability of therapeutic studies, we refer you to the Users' guides series.16 In this EBMH Note, we will discuss 4 questions that clinicians might find useful when considering applicability,1 and we will highlight our discussion with the following clinical scenario:

We see a 77 year old man in clinic who was recently diagnosed with Alzheimer's disease. His medical history is significant for a seizure disorder that is well controlled with dilantin. On examination, he scores 22/30 on the Mini-Mental State Examination. His wife found some information about donepezil while surfing the internet and wants to know if her husband could receive this treatment. Together, we decide to review the evidence and judge whether he is a candidate for donepezil to slow the deterioration in his cognitive status. Using the terms “donepezil” and “dementia,” we find a relevant review in the Cochrane Library. 7

Is my patient so different from those in the study that the results cannot be applied?

To rigidly apply the inclusion/exclusion criteria of a trial when extrapolating its results may result in harm.1 It is generally more appropriate to consider whether the underlying pathobiology in our patient is so different that the study cannot give any guidance about management. For most differences in patient groups, the answer to this question is “no,” and we should instead think about how these differences might shift the balance between the benefits and harms of treatment. Differences between our patients and those in the trials tend to be quantitative (eg, matters of degree in risk or responsiveness) rather than qualitative (no response or adverse response to treatment). This rule has a few exceptions because the same disease may affect patients differently in important …

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