Intended for healthcare professionals


New diagnostic tests: more harm than good

BMJ 2017; 358 doi: (Published 18 July 2017) Cite this as: BMJ 2017;358:j3314
  1. Bjørn Hofmann, professor1,
  2. H. Gilbert Welch, professor2
  1. 1Department of Health Sciences in Gjøvik, Norwegian University of Science and Technology, and Centre for Medical Ethics at the University of Oslo, PO Box 1130, Blindern, N-0318 Oslo, Norway
  2. 2Dartmouth Institute for Health Policy and Clinical Practice, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
  1. Correspondence to B Hofmann b.m.hofmann{at}

Although new diagnostics may advance the time of diagnoses in selected patients, they will increase the frequency of false alarms, overdiagnosis, and overtreatment in others. Bjorn Hofmann and H. Gilbert Welch explain how to minimise harm

Key messages

  • Innovative technologies and ample venture capital are combining to produce new disease biomarkers and mobile monitoring devices

  • These new diagnostics are technologically advanced but do not automatically provide improvements in clinical care and population health

  • They have the potential to help some but also to increase the frequency of false alarms, overdiagnosis, and overtreatment in others

  • Excessive testing and false alarms may increase healthcare workload and shift clinicians’ focus towards the healthy

  • Misleading feedback at both the population and individual levels tends to favour further market growth

  • Clinicians must provide a strong counterbalance: educating patients, respecting baseline risk, thinking downstream, and expecting misleading feedback

Advances in technology and availability of ample venture capital are combining to produce a growing array of new medical diagnostics. New biomarkers are being identified to predict or detect a wide range of diseases, and new devices are being developed continuously to monitor biological parameters—often connecting with mobile devices to provide user friendly updates of health status (m-health). One vision is that these new diagnostics will transform medicine from treating disease to promoting health, from being reactive to being proactive, and from being general to being personal.1 Another vision is less sanguine—that new diagnostics will warrant a warning of their downsides.

Efforts to detect disease early can always be accompanied by unintended harms. These include false alarms and indeterminate findings that can worry patients, drive more testing, increase clinical workload, and distract clinicians from more important work. Overdiagnosis can lead to unnecessary treatments. Promotional campaigns will necessarily need to get people concerned about disease and indicate that the path …

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