The WHO’s health bible - known as the International Classification of Disease (ICD) - determines what doctors around the world diagnose, treat and record.

However, Dr Stuart Calimport, one of the lead authors, cited inconsistencies such as sarcopenia, an age-related muscle-wasting, which was included in the ICD while age-related wearing out of other organs was not.

Critical to ageing is a process known as senescence in which cells throughout the body age, releasing inflammatory factors and enzymes that the immune system can no longer destroy

“When senescent cells build up in the skin causing wrinkles it is considered a ‘natural change.’ Yet when senescent cells build up in the heart and blood vessels, causing blood vessels to calcify, we call it ‘cardiovascular disease,’” said Dr Calimport, of Liverpool University.

“This is an error of logic and categorisation and not due to the intrinsic nature or complexity of pathology or disease.

“An ageing ‘disease’ classified and assessed for the level of severity in one organ can be unclassified in another.

“With a lack of classifications and staging, pathological ageing changes may not be logged. This means that treatment needs may be overlooked, such as atrophy, calcification and ageing in organs and tissues where these are not classified or assessed for severity.”

Dr Calimport did not believe the classification of more diseases would provide a bonanza for drug firms to develop treatments that would push up the NHS bill.

He said there were already cheap drugs such as Metformin, which was used to treat diabetes and had been shown to be effective in countering age-related conditions.

“It would allow for preventative medicine such as social prescribing or the prescribing of exercise. It might not totally prevent ageing but at the moment we are not even recognising ageing in a way that it can be properly recorded and tracked” said Dr Calimport.

“If you can’t track it, how can you prevent it, or slow it down?”

The WHO is currently considering submissions for changes to the ICD which will be published next year. There are major updates every decade.

The proposals comes as the number of elderly are expected more than double from 900 million worldwide aged over 60 to two billion by 2050.

By 2030, one in five people in the UK (21.8 per cent) will be aged 65 or over, 6.8 per cent will be aged 75-plus and 3.2 per cent will be aged 85-plus.