What is overdiagnosis?

Overdiagnosis is a problem that was first recognised some decades ago, but is now coming to serious attention in the research and healthcare communities.

Overdiagnosis occurs when commonly-used diagnoses in health and medical care, diagnoses that relevant health professionals would consider correct, do more harm than good. Overtreatment, which generally follows overdiagnosis, occurs when people get treatment they don’t need. Because they don’t need the treatment, they are unlikely to get any benefits from it, but may experience side effects or other harms.
There are a lot of reasons that overdiagnosis occurs. Expert panels agree to expand the definition of diseases, so that more and more people at lower and lower risk are diagnosed with the disease. Technology becomes increasingly sensitive, picking up smaller and smaller changes in the body that may never cause problems for the person. Diseases behave in unexpected ways: small cancers, for example, sometimes grow extremely slowly, or even go away, so they will never cause problems for the person, and there’s no benefit in knowing they are there. Diagnosing these people, people who don’t need to be diagnosed, leads to a number of problems including psychological harms like anxiety, physical harms like treatment complications, redirection of healthcare resources away from the people who need it and towards those who don’t, and the creation of more people in society who think of themselves as sick, or as survivors of a disease. The Figure below is a worst-case scenario illustration of how overdiagnosis and overtreatment happen in a population.

Overdiagnosis Diagram

Overdiagnosis is now acknowledged in many areas of medicine. Areas we will focus on include:

  • Mammograms for early detection of breast cancer
  • Ultrasound, CT scanning and MRI scanning for early detection of thyroid cancer
  • High-sensitivity troponin testing for early detection of myocardial ischaemia (to detect reduced blood flow to the heart)
  • Prostate Specific Antigen testing for early detection of prostate cancer
  • Genetic tests for risk assessment in inherited heart disease
  • Genetic tests used to predict whether people will develop haematological cancers (blood cancers)

It is counterintuitive to think that sometimes people don’t need to know that they have a ‘disease’. The methods for quantifying overdiagnosis are difficult and contested. Firmly-established healthcare practices are hard to change. These are just some of the reasons that it has been challenging to make progress on the problem of overdiagnosis. Wiser Healthcare aims to produce the research that is needed to support effective action to reduce overdiagnosis and overtreatment.