The discharge of almost 100 elderly patients in the Western Health Trust was delayed last December because of funding problems.
A report from Stormont's Public Accounts Committee (PAC) said institutional care for older people in Northern Ireland was costing £265 million a year.
It warned hold-ups in transfers to homes caused bed-blocking within hospitals and were not in the best interest of patients.
The report confirmed 99 people were left awaiting residential care and nursing home placements in the Western Trust during the final month of 2010.
It said: "The delays demonstrate how crucial it is that trusts manage available resources effectively, and reinforce the need for skilful co-ordination of health and social services to ensure that care arrangements for older people ready to leave hospital are in place promptly."
In Northern Ireland, around 9,500 older people have been placed in 490 registered residential care and nursing homes by health and social care trusts at a cost of around £265 million a year. Many have complex care needs and are among the most vulnerable in society, the paper said.
"While the committee appreciates the difficulties of managing the smooth and timely discharge of older people from hospital into appropriate care placements given current funding constraints, it does not consider that unnecessary retention in hospital is in anyone's best interests," it added.
The dossier added that delays in discharging patients experienced in the area covered by the Western Trust - which includes Londonderry, Limavady, Strabane, Omagh and Fermanagh - are not confined to that one trust.
"The committee recommends that the causes of delayed discharges throughout all trusts are thoroughly investigated and that prompt, well co-ordinated strategies are devised to ensure that patient discharge is managed effectively," it added.
SDLP committee member John Dallat welcomed the disclosures, saying: "I am glad that that is now on record, because the impression that we were getting was that everything was hunky-dory. There is a crisis developing."