Obesity and inactivity are fuelling a ‘massive expansion’ of ill health amongst the elderly, researchers warn.
The number of over-65s with four or more diseases will double to almost a fifth by 2035, they predict.
And while life expectancy is projected to increase for both men and women, most of these extra years will be spent living with ‘multiple morbidities’.
Within two decades, 17 % of over-65s can expect to suffer from at least four medical conditions – up from 9.8 % in 2015. The most common ailments include cancer, stroke, dementia, high blood pressure, diabetes, arthritis, lung disease, blindness and deafness.
Newcastle University researchers blamed ‘the higher prevalence’ of obesity and inactivity, which greatly increase the risk of several diseases.
Just under two-thirds of men and women in the UK are overweight or obese, and a quarter take almost no exercise.
Over-65s are the most sedentary age group, spending at least ten hours a day sitting down.
The study predicted that 53 % of the 65-to-74 age group will have two or more illnesses by 2035 – up from 45.7 % in 2015.
Once women reach 65, they will typically live for another 24.1 years, to 89.1, by 2035. This is up from 86.2 years in 2015 – but 17.2 will be spent living with two or more diseases, the research predicts.
Men will live for an additional 22.2 years on reaching 65, but 15.4 of them will be spent dealing with at least two illnesses.
Professor Carol Jagger, an expert in age-related illness at Newcastle University, wrote in the journal Age and Ageing: ‘Worryingly, our model shows that future “young-old” adults, aged 65 to 74 years, are more likely to have two or three diseases than in the past.
‘This is due to their higher prevalence of obesity and physical inactivity which are risk factors for multiple diseases.’
‘These findings have enormous implications for how we should consider the structure and resources for the NHS in the future. Multi-morbidity increases the likelihood of hospital admission and a longer stay, along with a higher rate of readmission, and these factors will continue to contribute to crises in the NHS.’
The proportion of over-65s with cancer will also double, from 12.6 % in 2015 to 23.7 % in 2035. Rates of arthritis, dementia, diabetes, stroke and lung diseases will also increase substantially.
NHS guidance states the risk of many of these illnesses can be reduced by older people taking at least 150 minutes of moderate exercise a week.
Caroline Abrahams, director at charity Age UK, said: ‘This research absolutely underlines the importance of getting our health and care services right for older people.
‘The increase in longevity over recent years has been a major achievement, but it also means we need to shift our focus to helping people to stay as well and independent as possible for as long as possible.
‘As we get older, our health and care needs tend to overlap and become more complex.
‘A more compassionate and intelligent approach to caring for older people must be a priority for us all.’
An NHS England spokesman said: ‘This study is further evidence of the need to integrate care, in the way the NHS is now beginning to do, so as to better support the growing number of older people with multiple health problems.’