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Primer: challenges in randomized and observational studies

Abstract

Randomized controlled trials (RCTs) are considered superior to observational studies, and both clinicians and researchers believe that conclusions that stem from observational research are flawed. RCTs, however, have important methodological and interpretational limitations, and particular clinical questions can only be addressed by observational research. This Review compares RCTs and observational studies with regard to particular limitations, and explains how the credibility of results from observational studies can be improved by making use of advanced analytical techniques.

Key Points

  • Randomized controlled trials have limitations that should not be ignored

  • Observational studies are closer to clinical practice, and can provide a wealth of information; however, these studies are prone to several biases

  • Recent advances in the analysis of observational studies can partially adjust for these biases

  • Prospective studies with multiple longitudinal assessments should be analyzed with appropriate longitudinal analytical techniques

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Figure 1: The longitudinal relationship between disease activity and radiographic progression in rheumatoid arthritis.

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Correspondence to Robert Landewé.

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The authors declare no competing financial interests.

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Landewé, R., van der Heijde, D. Primer: challenges in randomized and observational studies. Nat Rev Rheumatol 3, 661–666 (2007). https://doi.org/10.1038/ncprheum0626

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