HTA Agency, Poland
What we understand by ‘applicability’ is the application/use of the results from clinical trials (done on restricted, specially selected populations) to other groups/individual people for the use in one’s own medical practice (in other words, “usefulness of these results in own clinical practice”). A randomised trial only provides direct evidence of causality within that specific trial. As individual characteristics will affect the outcome for this person, it takes an additional logical step to apply this result to a specific individual.
Although closely related to concepts of generalisability and external validity, ‘applicability’ is broader in its scope, including issues related to the overall impact of treatment on individual patients. Wanting to make informed decisions on health care, when considering applicability it is important to take relevant individual factors/issues into consideration, such as :
- Biological Issues - differences between patients, pathophysiologic differences in the illness (whether the biology of the treatment effect will be similar in patients they are facing).
- Social and Economic Issues - important differences in patient as well as provider compliance (their own ability to deliver the intervention in a safe and effective manner).
- Epidemiologic Issues - co-morbid conditions, important differences in untreated patients' risk of adverse outcomes (their patients' risk of the target event that treatment is designed to prevent and of the side effects that may accompany treatment).
For full details, see Dans AL, Dans LF, Guyatt GH, Richardson S, for the Evidence-Based Medicine Working Group. How to decide on the applicability of clinical trial results to your patient. Centre for Health Evidence, Edmonton, Alberta. URL: www.cche.net/userguides/trials