Furthermore, the NAO report highlights the negative impact longer stays in hospital can have on older patient’s health.
The Royal College of Nursing (RCN) has called for greater investment in community services, which it says, will allow older people to receive more appropriate care.
Anna Crossley, RCN professional lead for acute, emergency and critical care, said: “Keeping an older person in hospital when they are well enough and want to go back to their own home benefits no-one.
“Older people’s routines are interrupted and their ability to cope by themselves reduced if they are needlessly kept in hospitals.
"This can lead to their health declining and a premature admission to a care home."
The NAO report emphasised the importance of achieving the correct balance between shorter delays and not discharging patients too soon.
The report says that data on delayed transfers of care under-estimate the range of delays that patients are experiencing.
Over the last two years there has been a 31% increase in days when acute hospital beds have been occupied by patients who have had their discharge unnecessarily delayed to 1.15 million days.
However, the report says these figures only account for delays after clinicians and other professionals believe a patient is ready to be discharged.
It does not take into account the patients who no longer need acute care, which, the report says increases this figure to approximately 2.7 million days.
While some efforts have been made to shorten hospital stays for older people, the report says these new figures call for more to be done as the population continues to age.
In 2014-15, 50% of older people were admitted to accident and emergency, compared to 16% of those under 65.
NAO recommends in the report that the Department of Health, NHS England and NHS Improvement set out how they intend to break the trend of rising delays in patient discharge.
Amyas Morse, head of the National Audit Office, said: “While there is a clear awareness of the need to discharge older people from hospital sooner, there are currently far too many older people in hospitals who do not need to be there.
“Without radical action, this problem will worsen and add further strain to the financial sustainability of the NHS and local government.”