Overdiagnosis: Good intentions gone bad

Peter was a thriving young software engineer; he is now on an extended leave of absence due to debilitating anxiety. It began with a CT scan for frequent migraines that showed a benign-appearing small intracranial mass.

The conspicuous finding led to an MRI that re-demonstrated the abnormality. The area of the brain was not amenable to biopsy; fortunately, the mass had remained completely stable with no growth over two years and was localized to an area of the brain that could not explain his symptoms. Despite the good news, Peter remained preoccupied with the possibility of something more ominous and found himself struggling to continue working and socializing.

Alfred is recently divorced. He was healthy until he underwent a prostate specific antigen (PSA) test as part of his routine check-up. An elevated PSA led to a prostate biopsy. A prostate biopsy led to surgery, which Alfred preferred over a “wait and watch” approach. Surgery led to nerve damage and erectile dysfunction that in turn led to irreparable marital strains.

Peter and Alfred have wildly different health problems, but they share one thing in common. They may have been victims of overdiagnosis. The term is now official: “overdiagnosis – the labeling of a person with a disease or abnormal condition that would not have caused the person harm if left undiscovered.” It can consist of creating diagnoses by medicalizing ordinary life experiences, expanding existing diagnoses by lowering thresholds or widening criteria without evidence of better health. Individuals derive no clinical benefit from overdiagnosis, although they may experience physical, psychological or financial harm.”

The problem of overdiagnosis has been recognized for decades but has received increasing attention over the past 10 years with a growing body of research demonstrating clearly that early detection does not always correlate to better outcomes. Take, for instance, cancer screening: slow growing and non-harmful tumors frequently may have never come to light or impacted an individual’s health had they been left undiagnosed. Since we lack the tools to clearly distinguish between the slow-growing and the harmful tumors, patients often receive treatment regardless.

But the proverb holds true: Nothing in life comes for free. No test or treatment comes without the possibility of consequences. Treatments – surgery, radiation, chemotherapy – are associated with harms. Even the knowledge of a possible finding, meaningful or not, can be harmful.

What makes this problem especially challenging is that it is impossible to know if a given diagnosis is, in fact, overdiagnosis.

What makes this problem especially challenging is that it is impossible to know if a given diagnosis is, in fact, overdiagnosis, hence the uncertainty in Peter and Alfred’s scenario.  Physicians and other health-care providers are ordering tests to help their patients. If some diagnoses are helpful and others are more harmful, and all are made with the intent of helping, it is tough to know where to draw the line. In fact, overdiagnosis is an inevitable, and even an essential, undesirable effect of appropriate testing.

Overdiagnosis is a problem that extends beyond cancer screening. The issue is prevalent in mental health, especially in the realm of attention deficit hyperactivity disorder (ADHD) and depression. It also has been evidenced in patients labeled with kidney dysfunction, polycystic ovary disease and in certain liver conditions. The phenomenon does not discriminate; it is prevalent in virtually every medical specialty that relies on diagnostic bloodwork and imaging tests including CT scans, ultrasounds and MRIs.

Overdiagnosis is a complex concept to grapple with, particularly in a world where missing important diagnoses is not without consequences, and where underdiagnosis and undertreatment are not uncommon. These two phenomena – underdiagnosis and overdiagnosis – appear to be opposite sides of the coin. In fact, they are not. Reducing overdiagnosis may help us re-direct efforts and resources toward frequently neglected areas in medicine where underdiagnosis is rampant.

Overdiagnosis is a natural consequence of good intentions in some cases, and in others, the direct consequence of thinking “more is always more.”

However, overdiagnosis is not an issue for physicians alone. It is an issue relevant to every individual that accesses the health-care system. When you are seeing your doctor and considering diagnostic workups or potential new diagnoses, stop and ask yourself (and your physicians):

  1. Do you understand the test and what it means to receive a positive or a negative result?
  2. Is the test result more likely to be helpful than harmful in guiding your medical care, and does the potential benefit outweigh the risk of incidental findings?

The Cumming School of Medicine at the University of Calgary has the privilege of hosting the international Preventing Overdiagnosis Conference during a four-day event, beginning June 9. The event is open to the public and media and we would encourage anyone interested in learning more to attend. If you are interested in attending, please register online or contact @ucalgary.ca.

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Eddy Lang


Eddy Lang is a Professor and Department Head for Emergency Medicine at Cumming School of Medicine, University of Calgary, and Alberta Health Services, Calgary Zone. He is a member of the GRADE working group and has led the development of GRADE-based clinical practice guidelines in pre-hospital care in the U.S. as well as with the International Liaison Committee for Resuscitation.

Arnav Agarwal


Arnav Agarwal is an internal medicine resident physician at the University of Toronto and an incoming fellow in general internal medicine at McMaster University. He has parallel interests in clinical epidemiology, narrative writing, medical education and health advocacy.

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