‘Preventing Overdiagnosis’ conference focuses on harms of health care

January 2020

Choosing Wisely champion Dr John Bonning was part of the New Zealand contingent attending the international Preventing Overdiagnosis conference, held in Sydney in December 2019.

Dr Bonning is president of the Australasian College for Emergency Medicine and an emergency medicine specialist at Waikato Hospital. He is on the Choosing Wisely New Zealand advisory group and is passionate about the need for clinicians and patients to understand the risks of over-diagnosis and over-treatment. The Choosing Wisely campaign supports reducing unnecessary tests, treatments and procedures in health care.

He says the conference  focused on the harm that can be caused by health care.

“Ray Moynihan’s quote that medicine’s much vaunted ability to help the sick and injured is soon to be outstripped by our propensity to harm the healthy, has never been more apt,” he says.

“We need to start thinking about the harm of tests and the harm of treatment in low-risk patients. There is a lot of discussion about things you can’t miss – and that’s very important – but there has also got to be an understanding of an unacceptable risk to a lot of people by over-treating, over-testing and over-diagnosing. A minor ‘just-in-case’ test can start a cascade of harm to patients.”

He tells the story of a young man who died as a result of unnecessary testing.

“He was in his 20s, and had stable epilepsy on Valproate (Epilim). He went to a new doctor who told him that for a small proportion of patients Valproate causes abnormal liver functions. He then had a liver function blood test, which showed just slightly abnormal results. So, an ultrasound of his liver was performed and it showed a cyst. It was then felt a biopsy was necessary to clarify what the cyst was. A week later he came into hospital tremendously unwell, developed overwhelming sepsis and infection and died.

“The histology from the biopsy came back as benign liver cyst. This was a cyst he was going to take to his grave, hopefully at an old age, so you could say he died as a result of somebody doing a simple set of liver function blood tests.”

Dr Bonning says he worries immensely about patients and clinicians not realising the risk of tests.

“If you do a complete body scan for trauma, there’s a greater than 80 percent chance – probably 90 percent – of an incidental finding that would worry you. Is it a thyroid nodule, is it an enlarged adrenal gland, is it a cyst on your liver or kidneys? And the vast majority of times, these things will not be harmful.”

He says cancer screening was under the spotlight at the conference.

“In general, the theme of the conference was that cancer screening – particularly screening of low-risk populations – is harmful. The PSA test is the posterchild for that. That test is causing a massive wave of overdiagnosis; people are being diagnosed with “cancer” that was never going to kill them, and end up impotent and incontinent as a result of the treatment. There are many non-aggressive forms of prostate cancer that people die with, not of. For every one person helped by avoiding aggressive prostate cancer, between 30 and 100 are harmed by over-diagnosis. Similar issues exist with other organs, including the thyroid.

“In cancer screening, you have to screen high-risk populations, people with symptoms or signs of disease or a strong genetic predisposition, not low-risk populations. You’ve got to understand rudimentary statistics including the difference between absolute and relative risks, and the potential harms involved. Treatments are often expressed as having risks and benefits, however this must be couched as “risk of harm and chance of benefit”. Benefits are not guaranteed and this must be weighed up.”

He says there was discussion about using a different term for low-risk cancer, such as atypical cells. “We need a 21st century definition of cancer not a 19th century one. Not using the “c” word for low-risk cancers would reduce anxiety and overtreatment.”

However, he stresses there are some populations who need more treatment, more investigations, and more screening.

“For example, your classic sore throat is likely to be viral, except for Māori and Pacific peoples, who are at higher risk of streptococcal infection and subsequent rheumatic fever. Treatment with antibiotics may be very appropriate in those cases. It’s very important that overdiagnosis messages don’t increase inequities for those who do need tests and treatments.”