Chapter 20. Numbers Needed to Treat Derived from Meta‒Analyses: Pitfalls and Cautions

  1. Matthias Egger1,
  2. George Davey Smith2 and
  3. Douglas G Altman3
  1. Shah Ebrahim

Published Online: 17 MAR 2008

DOI: 10.1002/9780470693926.ch20

Systematic Reviews in Health Care: Meta-Analysis in Context, Second Edition

Systematic Reviews in Health Care: Meta-Analysis in Context, Second Edition

How to Cite

Ebrahim, S. (2001) Numbers Needed to Treat Derived from Meta‒Analyses: Pitfalls and Cautions, in Systematic Reviews in Health Care: Meta-Analysis in Context, Second Edition (eds M. Egger, G. D. Smith and D. G. Altman), BMJ Publishing Group, London, UK. doi: 10.1002/9780470693926.ch20

Editor Information

  1. 1

    Senior Lecturer in Epidemiology and Public Health Medicine, Division of Health Services, Research and MRC Health Services Research Collaboration, Department of Social Medicine, University of Bristol, UK

  2. 2

    Professor of Clinical Epidemiology, Division of Epidemiology and MRC Health Services Research Collaboration, Department of Social Medicine, University of Bristol, UK

  3. 3

    Professor of Statistics in Medicine, ICRF Medical Statistics, Group, Centre for Statistics in Medicine, Institute of Health Sciences, University of Oxford, UK

Publication History

  1. Published Online: 17 MAR 2008
  2. Published Print: 1 JAN 2001

ISBN Information

Print ISBN: 9780727914880

Online ISBN: 9780470693926

SEARCH

Keywords:

  • meta-analyses;
  • treatment;
  • clinical setting;
  • systematic reviews;
  • risk reductions

Summary

This chapter contains section titled:

  • Summary Points

  • Describing the Effects of Treatment

  • The Effect of Choice of Outcome

  • Ineffective Treatments and Adverse Effects

  • The Effect of Variation in Baseline Risk

  • The Effects of Geographical and Secular Trends

  • The Effect of Clinical Setting

  • Trial Participants and Patients in Routine Clinical Practice

  • Pooling Assumptions and NNTs

  • Duration of Treatment Effect

  • Interpretation of NNTs

  • Deriving NNTs

  • Understanding of NNTs

  • Conclusion

  • Acknowledgements