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Overdiagnosis: what it is and what it isn’t
  1. John Brodersen1,2,
  2. Lisa M Schwartz3,
  3. Carl Heneghan4,
  4. Jack William O’Sullivan4,
  5. Jeffrey K Aronson4,
  6. Steven Woloshin3
  1. 1 Centre of Research & Education in General Practice, Department of Public Health, University of Copenhagen, Faculty of Health Sciences, Copenhagen, Denmark
  2. 2 Region Zealand, Primary Health Care Research Unit
  3. 3 Center for Medicine and the Media, The Dartmouth Institute for Health Policy and Clinical Practice, Dartmouth Medical School, Lebanon, New Hampshire, USA
  4. 4 Centre for Evidence-Based Medicine, Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford, UK
  1. Correspondence to Professor John Brodersen, Centre of Research & Education in General Practice, Department of Public Health, University of Copenhagen, Faculty of Health Sciences, Copenhagen 1014, Denmark; jobr{at}

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Why then, can one desire too much of a good thing?

William Shakespeare, As You Like It (1600)

Rosalind’s question, as she is about to marry Orlando, is purely rhetorical—she thinks that one cannot desire too much of a good thing. Nevertheless, trite though it may be, it is true that one can sometimes have it. It is certainly true of healthcare and has been referred to as ‘too much medicine’,1 although because of potential confusion with ‘too much medication’ a better term might be ‘too much healthcare’. This includes too much screening of asymptomatic individuals, too much investigation of those with symptoms, too much reliance on biomarkers, too many quasi-diseases, too much diagnosis, often leading to too much treatment, sometimes cost-ineffective, medicines that are too costly and too rapidly approved for marketing, too many adverse reactions, and too much inappropriate monitoring. And too much healthcare implies too little effective healthcare.

An older term, ‘overdiagnosis’ has been used to refer to a more restricted set of items. And although the term can be traced back as far as 1955,2 it is still difficult to define satisfactorily.

Broadly, overdiagnosis means making people patients unnecessarily, by identifying problems that were never going to cause harm or by medicalising ordinary life experiences through expanded definitions of diseases.

Overdiagnosis has two major causes: overdetection and overdefinition of disease. While the forms of overdiagnosis differ, the consequences are the same: diagnoses that ultimately cause more harm than benefit. Confusion about what constitutes overdiagnosis undermines progress to a solution. Here we aim to draw boundaries around what overdiagnosis is and to exclude what it is not.

What it is

Overdetection refers to the identification of abnormalities that were never going to cause harm, abnormalities that do not progress, that progress too slowly to cause symptoms or harm during a person’s remaining lifetime, or that …

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