Andrew Moore

Honorary senior research fellow in pain research at Nuffield Division of Anaesthetics at the University of Oxford

Author of: What is an NNT?

Andrew wears many hats; he is currently an honorary senior research fellow in pain research at Nuffield Division of Anaesthetics at the University of Oxford, the Managing Director of Bandolier Ltd, the Founding Editor of Bandolier, an evidence-based journal (1994) and a healthcare consultant. He was educated at the University of Oxford, where he received his BA, MA, DPhil DSc (Doctor of Science) and CChem FRSC (Fellow Royal Society of Chemistry).

Having completed over 30 years of biomedical research, Andrew has been involved with over 500 scientific and clinical publications, contributing to systematic reviews, meta-analyses and methodological improvement. He has also authored a number of books on evidence-based medicine and pain and approximately 200 systematic reviews, including many Cochrane reviews. He has achieved an H-index of over 70 for the impact and productivity of his published work.

Andrew holds several important posts; he is an honorary member of the British Pain Society and of the International Association for the Study of Pain, and an honorary professor of the School of Health Sciences at the University of Wales in Swansea. In 2009 he also became a member of the Fellowship of the Royal College of Anaesthetists and is the Chairman of the International Association for Study of Pain Systematic Review and Evidence special interest group.

Summary: What is an NNT?

  • The number needed to treat (NNT) has become a popular measure of effectiveness of interventions. NNTs are much easier to comprehend than any statistical description, and NNTs for different agents can be easily compared.
  • An NNT is treatment-specific and describes the difference between a treatment and a control in achieving a particular clinical outcome. It can be used to describe any outcome where event rates are available for both a treatment and a control.
  • Clearly defining a useful clinical outcome is the best way of calculating and using NNTs.
  • NNTs calculated from systematic reviews of randomised controlled trials provide the highest level of evidence because systematic reviews contain all the relevant information and the largest numbers of patients available for analysis.
  • NNTs only have utility when the evidence on which they are based fulfils criteria of quality, validity and size. Even data from a systematic review can be compromised.
  • An NNT is just one part of the information required in making a purchasing decision. There are many other factors, including adverse effects, costs, and individual, social and medical priorities.