Doctors risk overdiagnosing the most common and fastest-growing liver condition, exposing patients to harmful tests, according to a study published today.
It is estimated that one in four people in the world is suffering from non-alcoholic fatty liver disease (NAFLD), and there are concerns it could lead to cirrhosis.
Expert bodies in Europe are now calling for patients to be screened for the condition and the National Institute for Health and Care Excellence (NICE) in the UK has issued guidance to doctors indicating that at-risk groups should be tested.
But Dr Ian Rowe, liver specialist and academic fellow at the University of Leeds, in an article in The Lancet Gastroenterology and Hepatology, argued that the rush to identify the disease is not supported by the findings of published medical research.
He said the benefits of early diagnosis were unknown – and no licensed drug treatments were available to people who have NAFLD.
Dr Rowe said: "The case for screening is unproven – and the overwhelming published evidence suggests that the vast majority of people who have NAFLD live with the condition without it impacting on their health.
"For doctors to push for screening in those circumstances will lead to overdiagnosis, and it's known that overdiagnosis can be harmful because it exposes people to unnecessary investigations and treatments – they become labelled with a condition, and it adds to the costs of healthcare."
A new condition
The liver is the second largest organ in the body and, among other complex functions, it plays a central role in fighting infections and illness.
A healthy liver should contain little or no fat. It has been known for a long time that drinking too much alcohol causes fat to develop in the liver.
But in the mid-1980s, doctors began to find that in some people, fat build-up was happening in the absence of alcohol. The condition non-alcoholic fatty liver disease (NAFLD) was coined and is more likely in people who are overweight, obese, have type 2 diabetes or high cholesterol levels.
It can lead to inflammation and scarring of the liver and cirrhosis, a serious and life-threatening condition. But those conditions take years to develop and only occur in a small minority of people with NAFLD.
In his review of the published scientific evidence, Dr Rowe said there had been a small number of studies that suggested NAFLD was an aggressive condition that increases the risk of progressive liver disease.
But he added that those studies were open to critique because of the small number of patients tracked and possible bias in the way they were selected for investigation, factors which have overstated the threat the disease poses and created a "...heightened anxiety around the need to diagnose NAFLD".
For patients with NAFLD, the main causes of death are heart disease and cancer.
Evidence of over diagnosis
Dr Rowe said data for England shows that in 2016, 66,276 people were admitted to hospital with NAFLD listed as one of the reasons why – a 27-fold increase on the figure for 2001.
But for the same period, the number of deaths where NAFLD was listed as the primary cause went from 165 to 412 – only a threefold increase.
Dr Rowe said that since only a small minority of patients with NAFLD will suffer complications linked to the condition, this made real the risk that people were undergoing unnecessary invasive investigations – including liver biopsy, where a small sample of the liver is removed.
He said for screening to be introduced, research was needed to identify the benefits and harms of early diagnosis, to understand the impact that diagnosis might have on patients and the public.
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