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When should we believe nonrandomized studies of comparative effectiveness?

S Hennessy1

  • 1Center for Clinical Epidemiology and Biostatistics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA. hennessy@upenn.edu

Clinical Pharmacology and Therapeutics
|November 18, 2011
PubMed
Summary

Demand for comparative-effectiveness trial data exceeds supply. When using nonrandomized studies, assess treatment comparability, effect size, biological plausibility, supporting evidence, new user status, valid endpoints, and result replication to mitigate bias.

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Area of Science:

  • Health Services Research
  • Clinical Epidemiology
  • Biostatistics

Background:

  • Randomized comparative-effectiveness trials (RCTs) are the gold standard but are resource-intensive.
  • The demand for comparative-effectiveness data often surpasses the supply of RCTs.
  • Nonrandomized studies are frequently used but are prone to various biases.

Purpose of the Study:

  • To outline critical factors for evaluating the quality and reliability of nonrandomized comparative-effectiveness studies.
  • To guide researchers and clinicians in assessing the validity of evidence from nonrandomized sources.

Main Methods:

  • This work is a critical review and synthesis of methodological considerations for nonrandomized studies.
  • Key factors for bias assessment in comparative-effectiveness research are identified and discussed.

Main Results:

  • Several factors must be considered when interpreting nonrandomized comparative-effectiveness studies.
  • These include treatment comparability, magnitude of observed differences, biological plausibility, supporting evidence, new user design, valid endpoint recording, and result replication.

Conclusions:

  • Careful examination of specific methodological elements is crucial for drawing valid conclusions from nonrandomized comparative-effectiveness studies.
  • Adherence to these guidelines can improve the trustworthiness of evidence derived from nonrandomized research.