The rate of so-called bed blocking in hospitals in England has almost doubled in the six months to November 2014, new figures reveal.
Research by Age UK shows that over 1.9 million bed days were lost to the NHS in the four years to June 2014, equivalent to 482,000 bed days each year.
But that figure rose by more than 400,000 between June and November 2014 - almost a year's worth in just six months.
Bed blocking refers to when patients are medically fit to be discharged from hospital, but have to stay because their care package is not ready yet.
The cost to the NHS over the entire period covered by the data is estimated to be in excess of £640 million, not including any food or treatments to the patients.
Hospital staff cannot discharge the patients accused of bed blocking for a range of reasons.
Some are waiting for health and social care support, like physiotherapy or a hot meals service, to be provided at their home. Other require adaptations to their homes, like ramps or grab rails.
The figures do not specify the age of those waiting to be discharged, but Age UK believes that most are elderly patients.
The average waiting time for a patient to be discharged is 28.5 days, but ITV News has spoken to patients who have been waiting for more than 45 days.
According to the figures from Age UK, the majority of bed days lost (61%) are due to patients waiting for a place in a residential care home or nursing home.
Around 8% are simply waiting for adaptations to their home, and a further 28% are waiting for a care package involving health professionals or carers who visit their home regularly.
Caroline Abrahams, Charity Director at Age UK said the solution lies in the provision of better social care: