Erschienen in:
01.08.2010 | Editorial
Efficacy assessed in follow-ups of clinical trials: methodological conundrum
verfasst von:
Robert BM Landewé
Erschienen in:
Arthritis Research & Therapy
|
Ausgabe 4/2010
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Abstract
Increasingly, we see papers describing the long-term follow-up results of randomised clinical trials. Sometimes, like the article by Rantalaiho and colleagues in the previous issue of Arthritis Research & Therapy, the follow-up extends to more than 10 years. It is not uncommon that authors of such articles describe their results as a comparison of the original treatment groups in the original randomised clinical trial. Methodologically, such a comparison is fallible for several reasons. In this editorial, two important sources of bias that may jeopardise the results of such follow-up studies are discussed: confounding by indication and confounding by trial completion.