Overdiagnosis of diseases and disorders could be doing more harm than good while wasting millions of dollars on unnecessary treatment, an Australian researcher says.
The trend towards overdiagnosis posed a significant risk to individuals' health, with estimates about $200 billion is spent every year in the United States on unnecessary care, an article published in the British Medical Journal (BMJ) today said.
Overdiagnosis occurs when people are diagnosed with a condition that would never have caused harm.
Advances in screening technology were a major contributor to detecting abnormalities that would not have caused symptoms, the article's authors, including Bond University's Ray Moynihan, wrote.
Mr Moynihan said screening the healthy population was a double-edged sword.
While it made sense to detect and treat disease early, there was also a risk of labelling people as sick and of unnecessary treatment, he said.
"We are now seeing evidence that this is happening in many conditions, particularly in cancer, and particularly in breast and prostate cancer," Mr Moynihan said.
The article cited international research, published in the BMJ in 2009, which concluded about one-third of all detected breast cancers may be overdiagnosed.
Canadian research suggested about 30 per cent of those diagnosed with asthma did not have the respiratory disease.
Studies also showed chronic kidney disease, gestational diabetes, and high blood pressure and cholesterol had also been overdiagnosed.
Conditions like ADHD were also the subject of much debate about overdiagnosis, the authors wrote.
"This is not about trying to scare people away from valuable medical interventions," Mr Moynihan said.
"It is about saying we need to be more cautious when we are offering tests or treatments to healthy people.
"We seem to be in an age where we hand out diagnoses like lollies in the same way that in some instances we hand out medications like lollies."
Other factors driving overdiagnosis were good intentions, fuelled by the fear of missing early signs of disease, the authors wrote.
But commercial and professional vested interests also played a part.
Resources now spent on overdiagnosing could be better used to treat or prevent genuine illness, the article said.
Early screening of prostate cancer has been in the headlines in the past week after the US Preventive Services Task Force advised men against taking the blood tests.
Cancer Council Australia chief executive Ian Olver said overdiagnosis would occur to some extent with early detection.
He said the best way to minimise overdiagnosis was to selectively screen people at greatest risk from disease.
Breast Cancer Network Australia chief executive Maxine Morand, who was diagnosed with breast cancer last year after a routine test, said regular screening prevented breast cancer deaths and early detection improved survival rates.
Prostate Cancer Foundation of Australia chief Dr Anthony Lowe said the biggest study of prostate cancer testing showed a more than 20 per cent reduction in deaths, but it also showed overdiagnosis did occur.
The PCFA was working on national guidelines for testing, he said.
REASONS AND EXAMPLES OF OVERDIAGNOSIS:
Breast cancer - Up to a third of screening detected cancers may be overdiagnosed.
Prostate cancer - More than 60 per cent risk that a cancer detected by prostate specific antigen (PSA) testing is overdiagnosed.
Chronic kidney disease - Controversial definition classifies 1 in 10 as having disease. Concerns many elderly people are overdiagnosed.
Thyroid cancer - Increase in incidence may be overdiagnosis.
Lung cancer - 25 per cent or more of screening detected lung cancers may be overdiagnosed.
Asthma - Canadian study suggests 30 per cent of people with diagnosis may not have asthma.
Gestational diabetes - Expanded definition classifies almost 1 in 5 pregnant women.
High blood pressure - Review suggests possibility of substantial overdiagnosis.
High cholesterol - Estimates up to 80 per cent of people with near-normal cholesterol treated for life may be overdiagnosed.
Attention deficit hyperactivity disorder - Widened definitions have led to concerns about overdiagnosis.
- Technological changes detecting ever smaller "abnormalities".
- Commercial and professional vested interests.
- Conflicted panels producing expanded disease definitions and writing guidelines.
- Legal incentives punishing underdiagnosis but not overdiagnosis.
- Health system incentives favouring more tests and treatments.
- Cultural beliefs that more is better; faith in early detection unmodified by risks.
Source: Preventing overdiagnosis: how to stop harming the healthy, British Medical Journal.